Co-reporter:Chao Li, Xin Chen, Fuyuan Zhang, Xingxing He, Guozhen Fang, Jifeng Liu, and Shuo Wang
Analytical Chemistry October 3, 2017 Volume 89(Issue 19) pp:10431-10431
Publication Date(Web):August 14, 2017
DOI:10.1021/acs.analchem.7b02430
Glucose assay is of great scientific significance in clinical diagnostics and bioprocess monitoring, and to design a new glucose receptor is necessary for the development of more sensitive, selective, and robust glucose detection techniques. Herein, a series of cyclic peptide (CP) glucose receptors were designed to mimic the binding sites of glucose binding protein (GBP), and CPs’ sequence contained amino acid sites Asp, Asn, His, Asp, and Arg, which constituted the first layer interactions of GBP. The properties of these CPs used as a glucose receptor or substitute for the GBP were studied by using a quartz crystal microbalance (QCM) technique. It was found that CPs can form a self-assembled monolayer at the Au quartz electrode surface, and the monolayer’s properties were characterized by using cyclic voltammetry, electrochemical impedance spectroscopy, and atomic force microscopy. The CPs’ binding affinity to saccharide (i.e., galactose, fructose, lactose, sucrose, and maltose) was investigated, and the CPs’ sensitivity and selectivity toward glucose were found to be dependent upon the configuration,i.e., the amino acids sequence of the CPs. The cyclic unit with a cyclo[-CNDNHCRDNDC-] sequence gave the highest selectivity and sensitivity for glucose sensing. This work suggests that a synthetic peptide bearing a particular functional sequence could be applied for developing a new generation of glucose receptors and would find huge application in biological, life science, and clinical diagnostics fields.
Co-reporter:Hai-bin Liu, Xin-jun Du, Yu-Xuan Zang, Ping Li, and Shuo Wang
Journal of Agricultural and Food Chemistry November 29, 2017 Volume 65(Issue 47) pp:10290-10290
Publication Date(Web):November 2, 2017
DOI:10.1021/acs.jafc.7b03957
Rapid, sensitive, point-of-care detection of bacteria is extremely important in food safety. To address this requirement, we developed a new surface-enhanced Raman scattering (SERS)-based lateral flow (LF) strip biosensor combined with recombinase polymerase amplification (RPA) for simultaneous detection of Listeria monocytogenes and Salmonella enterica serotype Enteritidis. AuMBA@Ag core–shell nanoparticles were used in this SERS-LF. Highly sensitive quantitative detection is achieved by measuring the characteristic peak intensities of SERS tags. Under optimal conditions, the SERS intensities of MBA at 1077 cm–1 on test lines are used to measure S. Enteritidis (y = 1980.6x – 539.3, R2 = 0.9834) and L. monocytogenes (y = 1696.0x – 844, R2 = 0.9889), respectively. The limit of detection is 27 CFU/mL for S. Enteritidis and 19 CFU/mL for L. monocytogenes. Significantly, this SERS-LF has high specificity and applicability in the detection of L. monocytogenes and S. Enteritidis in food samples. Therefore, the SERS-LF is a feasible method for the rapid and quantitative detection of a broad range of bacterial pathogens in real food samples.Keywords: food safety; foodborne pathogen; recombinase polymerase amplification; surface-enhanced Raman scattering;
Co-reporter:Hai-bin Liu, Yu-Xuan Zang, Xin-jun Du, Ping Li, Shuo Wang
Journal of Dairy Science 2017 Volume 100, Issue 9(Volume 100, Issue 9) pp:
Publication Date(Web):1 September 2017
DOI:10.3168/jds.2017-12566
The efficient and timely detection of pathogens is a major concern worldwide. The aim of this study was to establish a rapid detection method for Salmonella bacteria in food samples to facilitate timely treatment. Widely used detection methods currently include culture-based methods and PCR-based methods. The former are time consuming, requiring 2 to 3 d, whereas the latter have higher accuracy but are typically complicated, requiring expertise and expensive instruments. In this study, a sensitive and rapid approach for the visual and point-of-use detection of Salmonella bacteria based on recombinase polymerase amplification (RPA) and a lateral-flow (LF) nucleic acid strip was established. We designed a pair of primers according to the invA gene of Salmonella bacteria: one was modified with digoxin, and the other was modified with biotin. In the presence of the biotin- and digoxin-modified primers and target DNA, the RPA produced a substantial amount of duplex DNA attached to biotin and digoxin. The products were detected using LF strips through immunoreaction: anti-digoxin antibodies on the gold nanoparticles, digoxin on the duplex, streptavidin on the LF test line, and biotin on the duplex. The developed RPA-LF assay allowed detection of Salmonella genomic DNA in less than 20 min with simple water bath equipment or portable thermal equipment. In addition, the RPA-LF assay was highly sensitive, with a detection limit as low as 20 fg of target DNA or 1.05 × 101 cfu of bacteria in pure culture, and highly specific, exhibiting no cross-reaction with Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, Shigella, Enterobacter aerogenes, or Campylobacter jejuni. Importantly, Salmonella could be detected in milk and chicken breast at concentrations as low as 1.05 × 100 cfu/mL or 1.05 × 100 cfu/g after enrichment for 2 h and in eggs at 1.05 × 100 cfu/g after enrichment for 4 h. Furthermore, RPA was more sensitive than PCR, which requires a thermal cycling device. In summary, this study describes a sensitive, simple, and point-of-use detection method for Salmonella bacteria.
Co-reporter:Mingfei Pan;Xiaojun Wang;Junping Wang;Yang Lu;Kun Qian
Food Analytical Methods 2017 Volume 10( Issue 6) pp:2027-2035
Publication Date(Web):27 December 2016
DOI:10.1007/s12161-016-0752-7
In this research, a reproducible surface plasmon resonance (SPR) immunosensor based on inhibition format was fabricated for stable and sensitive detection of four sulfonamides (SAs) in animal-derived foods. The parameters in the fabrication and measurement process were optimized and discussed in details. The method using the proposed SPR immunosensor was validated and exhibited favorable performance for SAs residues detection in common animal-derived food products, as well as acceptable accuracy (pure milk 88.5–106.2%; egg 89.0–91.5%; chicken muscle 87.2–94.7%; beef 84.8–96.9%; fish 87.8–95.0%), precision (relative standard deviation (n = 3), pure milk 3.2–5.2%; egg 1.1–5.4%; chicken muscle 1.1–5.9%; beef 2.5–7.1%; fish 4.6–5.3%), and sensitivity (IC15, pure milk 59.6 ng mL−1, egg 56.1 ng mL−1, chicken muscle 66.9 ng mL−1, beef 63.3 ng mL−1, fish 62.7 ng mL−1). Each detection cycle could finish in less than 5 min, and each SPR chip could reuse 300 analysis cycles with response attenuation of 3.7%. These results have demonstrated that the proposed SPR immunosensor has offered an effective, accurate, sensitive, rapid, and low-cost methodology for SAs residue detection in food sample, and this method has great potential for the routine analysis of large numbers of samples on measuring different kinds of compounds.
Co-reporter:Qing-Hua Wang;Guo-Zhen Fang;Yao-Yao Liu;Dong-Dong Zhang
Food Analytical Methods 2017 Volume 10( Issue 7) pp:2585-2592
Publication Date(Web):29 January 2017
DOI:10.1007/s12161-017-0795-4
A novel procedure for fluorescent sensing of histamine was developed using surface molecular imprinting on quantum dots modified by ionic liquid. The sensing material was synthesized via a facile one-pot route on the surface of CdSe/ZnS quantum dots (QDs), and in this process, ionic liquid (IL) was successfully introduced by electrostatic interactions to strengthen the fluorescent stability of QDs and the fluorescence sensitivity of the synthesized materials that was called QDs@IL@MIP. QDs@IL@MIP was characterized by fluorescence spectrophotometer, scanning electron microscopy (SEM), and infrared spectroscopy. The fluorescence of QDs@IL@MIP can be strongly enhanced by histamine (HA) which can be determined in a wide concentration range of 0.449–2.249 mM with a low limit of detection (LOD) of 0.11 mM.
Co-reporter:Qiang ZHANG, Rui-Xue LI, Xin CHEN, Xing-Xing HE, ... Shuo WANG
Chinese Journal of Analytical Chemistry 2017 Volume 45, Issue 5(Volume 45, Issue 5) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/S1872-2040(17)61013-2
Fluorescence spectroscopy was used to investigate the efficiency of coupling peptides to gold nanoparticles via 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride-N-hydroxysuccinimide (EDC-NHS). In this study, the effects of experiment conditions including the buffer solution (PBS, HEPES, Tris-HCl, and borate buffer solution), pH (6.5–9.0) and concentrations of buffer solution (10, 25, 40 and 50 mM), concentrations of NHS and EDC (from 0.2 M NHS-0.01 M EDC to 1.0 M NHS-0.5 M EDC), ratios of NHS to EDC (0, 0.5, 1.0, 2.0 and 2.5), and the coupling reaction time (4, 8, 12, 24 and 36 h) on the coupling efficiency were investigated and the optimized conditions were developed. These results indicated that the optimal experimental conditions were: pH 7.0 and 25 mM of the HEPES buffer solution, the concentrations ratios of NHS to EDC of 2:1 (0.4 M NHS-0.2 M EDC), and coupling reaction time of 24 h.The coupling efficiency of peptides to modified nanoparticles was optimized by investigating the species of buffer solution, pH value, concentrations of buffer solution, concentrations of NHS and EDC, ratios of NHS to EDC, coupling reaction time.Download high-res image (65KB)Download full-size image
Co-reporter:Yukun Yang, Guozhen Fang, Xiaomin Wang, Fuyuan Zhang, Jingmin Liu, Wenjie Zheng, Shuo Wang
Electrochimica Acta 2017 Volume 228(Volume 228) pp:
Publication Date(Web):20 February 2017
DOI:10.1016/j.electacta.2017.01.043
•Electrochemiluminescent MoS2-GQDs nanocomposite was fabricated for the first time.•MoS2-GQDs hybrid nanocomposite was used as ECL sensing platform.•Molecularly imprinted ECL sensor was fabricated for the determination of MCPA.•MoS2-GQDs nanocomposite may advance the developments of ECL sensor.The ECL properties and application of a novel luminescent material molybdenum disulfide-graphene quantum dots (MoS2-GQDs) hybrid nanocomposite was reported for the first time. The hybridization of MoS2 and GQDs endowed nanocomposite with structural and compositional advantages for boosting the ECL performance of GQDs. Impressively, the ECL could be remarkable enhanced using MoS2-GQDs hybrid nanocomposite, which was ∼13, ∼185 and ∼596-folds larger than the ECL intensity of GQDs, MoS2 modified electrodes and bare electrode, respectively. Subsequently, as a sensing platform, the MoS2-GQDs hybrid nanocomposite was applied to fabricate molecularly imprinted electrochemiluminescence sensor for the ultrasensitive and selective determination of 2-methyl-4-chlorophenoxyacetic acid. Under optimal conditions, the detection limit of the prepared sensor was 5.5 pmol L−1 (S/N = 3) within a linear concentration range of 10 pmol L−1–0.1 μmol L−1. The developped sensor exhibited high sensitivity, good selectivity, reproducibility and stability, suggesting the potential for detecting pesticides and veterinary drugs at trace levels in food safety and environmental control.Download high-res image (145KB)Download full-size image
Co-reporter:Shujun Wang, Tiangui Li, Shuo Wang, Les Copeland
Carbohydrate Polymers 2017 Volume 175(Volume 175) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.carbpol.2017.08.014
•HA pre-treatment increased reaction efficiency of OSA modification.•F/T pre-treatment decreased efficiency of OSA modification of starch.•OSA-HAF-starch had higher pasting viscosities than other OSA-starches.•OSA modification disrupted mainly the short range structural order of starch.Pre-treatments by freezing/thawing (F/T) and hydrothermal-alkali (HA) were used in the modification of starch with octenyl succinic anhydride (OSA). In comparison with OSA-modified starch prepared without pre-treatment (degree of substitution, DS = 0.0172; reaction efficiency, RE = 73.9%), HA pre-treatment increased the DS of OSA-starch and RE of subsequent OSA modification (0.0185 and 79.7%, respectively). In contrast, F/T pre-treatment gave the opposite results (0.0152 and 65.5%, respectively). OSA modification markedly increased the viscosities but decreased the gelatinization parameters of native starch. Esterification of starch by OSA was confirmed with Fourier transform infrared and Raman spectroscopy, which indicated markedly decreased short-range molecular orders of native starch. The present study showed that HA pre-treatment before OSA modification is an efficient way to improve the reaction efficiency of OSA with starch and thereby to modify the pasting properties of starch. F/T pre-treatment did not increase the reaction efficiency of starch with OSA.
Co-reporter:Shujun Wang, Peng Guo, Fengjuan Xiang, Jinrong Wang, Jinglin Yu, Shuo Wang
Carbohydrate Polymers 2017 Volume 174(Volume 174) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.carbpol.2017.06.120
•Effects of annealing (ANN) and ultrahigh pressure (UHP) on starch were studied.•ANN treatment increased stability of wheat starch to subsequent UHP treatment.•Some dual treatments increased the viscosity of single-modified wheat starch.•Dual modification altered slightly the structures of yam and potato starches.•ANN treatment was proposed to increase ordering of amorphous regions.The effects of dual modification by annealing (ANN) and ultrahigh pressure (UHP) on properties of wheat, yam, and potato starches were investigated. Compared with the single UHP treatment (400 MPa), ANN-UHP (400 MPa) treatment did not alter significantly the ordered structures of wheat starch, indicating that ANN treatment enhanced the stability and resistance of starch granules to the subsequent UHP treatment. In contrast, UHP (400 MPa)-ANN treatment resulted in more severe disruption of ordered structures of wheat starch than did the single UHP treatment, showing that UHP-treated starch was more vulnerable to the subsequent ANN treatment. The dual modifications had little effect on granular structures of yam and potato starches. ANN-UHP (300 and 400 MPa) and UHP (300 MPa)-ANN treatments enhanced greatly the pasting viscosities of UHP-modified starches. Dual modifications altered greatly the pasting properties of yam and potato starches, as observed for the single ANN treatment. From this study, we proposed that ANN treatment enhanced stability of wheat starch by increasing interaction of starch chains in amorphous regions.
Co-reporter:Xiaodong Lin, Yaqing Liu, Zhanhui Tao, Jinting Gao, Jiankang Deng, Jinjin Yin, Shuo Wang
Biosensors and Bioelectronics 2017 Volume 94(Volume 94) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.bios.2017.01.008
•A novel nanozyme-base bio-barcode assay is developed for multiple DNAs detection.•The strategy presents excellent sensitivity and specificity.•HIV and HCV genes can be simultaneously detected in an enzyme-free and label-free condition.•Multiple DNAs can be individually detected under INHIBIT-OR logic function control.•The provided assay can distinguish single-base mismatched mutant from target DNA.Since HCV and HIV share a common transmission path, high sensitive detection of HIV and HCV gene is of significant importance to improve diagnosis accuracy and cure rate at early stage for HIV virus-infected patients. In our investigation, a novel nanozyme-based bio-barcode fluorescence amplified assay is successfully developed for simultaneous detection of HIV and HCV DNAs with excellent sensitivity in an enzyme-free and label-free condition. Here, bimetallic nanoparticles, PtAuNPs, present outstanding peroxidase-like activity and act as barcode to catalyze oxidation of nonfluorescent substrate of amplex red (AR) into fluorescent resorufin generating stable and sensitive "Turn On" fluorescent output signal, which is for the first time to be integrated with bio-barcode strategy for fluorescence detection DNA. Furthermore, the provided strategy presents excellent specificity and can distinguish single-base mismatched mutant from target DNA. What interesting is that cascaded INHIBIT-OR logic gate is integrated with biosensors for the first time to distinguish individual target DNA from each other under logic function control, which presents great application in development of rapid and intelligent detection.
Co-reporter:Gaoshuang Hu, Wei Sheng, Jingmin Li, Yan Zhang, Junping Wang, Shuo Wang
Analytica Chimica Acta 2017 Volume 982(Volume 982) pp:
Publication Date(Web):22 August 2017
DOI:10.1016/j.aca.2017.06.013
•Two novel FQICS based on FRET were developed for the first time.•QDs and UCNPs were used as fluorescent donors in the FQICS.•The proposed FQICS showed low LOD compared with traditional ICS.•The proposed FQICS were applied in real samples analysis.•The proposed FQICS were verified by commercial ELISA kits.In this study, two novel fluorescence quenching immune chromatographic strips (FQICS) were developed to detect sulfaquinoxaline (SQX) in foods of animal origin. These proposed FQICSs were based on fluorescence resonance energy transfer (FRET) from fluorescence donors (quantum dots or upconversion nanoparticles) to fluorescence acceptors (colloidal gold nanoparticles). Compared with traditional colloidal gold-based immune chromatographic strips (ICS), these FQICSs showed positive correlation between the fluorescent signals and the targets, and allowed user to get test results from weak fluorescent signals. The visual detection limits of these two FQICSs were both 1 ng mL−1 in standard solution and 8 μg kg−1 in samples, while the visual detection limit of the colloidal gold-based ICS was 10 ng mL−1 in standard solution and 80 μg kg−1 in samples. Besides, the results we obtained by the use of FQICS showed high agreement with those obtained by the use of commercial ELISA kits, indicating the good accuracy of these strips. As a conclusion, these proposed FQICS based on quantum dots and upconversion nanoparticles can be applied in sensitive, rapid and on-site detection of SQX in foods of animal origin.Download high-res image (217KB)Download full-size image
Co-reporter:Cuicui Liu, Qiliang Deng, Guozhen Fang, Meng Dang, Shuo Wang
Analytical Biochemistry 2017 Volume 530(Volume 530) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.ab.2017.04.014
Alpha-fetoprotein (AFP) is widely used as a tumor marker for the serum diagnosis of primary hepatoma. Sensitive detection of AFP level plays an important role in the early diagnosis of disease and highly reliable prediction. In this study, a novel non-competitive immunoassay (IA) based on poly(guanidinium ionic liquid) monolithic material was developed for detecting ultra trace levels of AFP in capillary electrochromatography (CEC) mode. The AFP was mixed with an excess amount of fluorescently labeled antibody. After incubation, the immunocomplex was separated from the free labeled antibody and detected by CEC coupled with laser-induced fluorescence detector. Under the optimized conditions, the developed CEC-IA performed a low detection limit of 0.05 μg L−1 (S/N = 3) and a wide linearity ranging from 0.1 to 1000 μg L−1 for AFP, which can be largely attributed to the high separation and enrichment efficiency of poly(guanidinium ionic liquid) monolithic material for the targets. The application of this method was demonstrated by determining AFP in human serum.
Co-reporter:Yaguang Yun, Mingfei Pan, Guozhen Fang, Yukun Yang, Ting Guo, Jiankang Deng, Bing Liu, Shuo Wang
Sensors and Actuators B: Chemical 2017 Volume 238() pp:32-39
Publication Date(Web):January 2017
DOI:10.1016/j.snb.2016.06.165
•A novel molecularly imprinted electrochemical sensor was developed for amantadine residue detection.•The MIP electrodeposition sensor exhibits good selectivity and sensitivity towards amantadine.•This work has broaden the application of MIP sensors in the field of drug residue determination.A novel molecularly imprinted electrochemical sensor was successfully fabricated for detection of amantadine (AM) residue in animal-derived foods. This molecularly imprinted film was prepared by electrodepositing o-aminothiophenol (o-AT) on a gold electrode surface by cyclic voltammetry (CV). A series of parameters, including template/monomer ratio, CV scanning cycle number, and immersion time, were optimized in detail for controlling the performance of this imprinted sensor. The fabricated sensor exhibited remarkable characteristics of high selectivity, sensitivity, and reproducibility, and long-term stability for AM detection. The imprinting factor for AM achieved to 2.33 and the selectivity factor for three structural analogues achieved to 6.20, 5.29 and 3.95. Under optimal experimental conditions, good linearity was observed between the current response and AM concentration, ranging from 4.0 × 10−7 mmol L−1 to 8.0 × 10−6 mmol L−1, with a detection limit of 3.06 × 10−9 mmol L−1 (S/N = 3). Satisfactory results for the measurement of real samples were also obtained using the proposed sensor, and were consistent with those derived from typical high-performance liquid chromatography-tandem mass spectrometry with a high correlation coefficient (R2 > 0.99). These results demonstrate that the proposed sensor could serve as a valuable tool for accurate and reliable detection of AM residue in animal-derived foods.
Co-reporter:Shujun Wang, Peiyan Li, Teng Zhang, Jinglin Yu, Shuo Wang, Les Copeland
LWT - Food Science and Technology 2017 Volume 84(Volume 84) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.lwt.2017.06.023
•Cooking method had little effect on in vitro starch digestion in rice flours.•Pressure cooking at low water content favored formation of amylose-lipid complex.•Cooked waxy flour displayed less starch hydrolysis than cooked non-waxy flours.•Viscosity of the gelatinized starch influenced in vitro digestion of cooked rice.This study evaluated the effects of different cooking methods on in vitro starch digestibility of three rice varieties. Results from differential scanning calorimetry and X-ray diffraction of cooked rice flours showed that rice starch was completely gelatinized after cooking. The overall paste viscosities of cooked indica hybrid flour (IHF) and japonica flour (JF) were lower than those of their corresponding raw flours. However, cooked waxy flour (WF) showed much higher paste viscosities than raw flours, especially the viscosity at the start of RVA testing. Cooking increased greatly the rate and extent of starch digestion of IHF and JF, but had a small effect on WF. There were small differences in rate and extent of starch digestion of rice after cooking under various conditions. Cooking methods were found to have little effect on in vitro starch digestibility of rice. Viscosity of the gelatinized waxy starch matrix affected in vitro starch digestibility. This study enables us to gain a better understanding of cooking effects on in vitro digestibility of starch in rice flour.
Co-reporter:Xin-jun Du, Tian-jiao Zhou, Ping Li, Shuo Wang
Molecular and Cellular Probes 2017 Volume 34(Volume 34) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.mcp.2017.05.004
•The tHDA-strip can be used to detect Salmonella in an easy way.•The tHDA-strip can be used to detect Salmonella with high sensitivity.•The whole detection procedures for real samples can be finished within 4–6 h.Salmonella is a major foodborne pathogen that is widespread in the environment and can cause serious human and animal disease. Since conventional culture methods to detect Salmonella are time-consuming and laborious, rapid and accurate techniques to detect this pathogen are critically important for food safety and diagnosing foodborne illness. In this study, we developed a rapid, simple and portable Salmonella detection strategy that combines thermophilic helicase-dependent amplification (tHDA) with a lateral flow assay to provide a detection result based on visual signals within 90 min. Performance analyses indicated that the method had detection limits for DNA and pure cultured bacteria of 73.4–80.7 fg and 35–40 CFU, respectively. Specificity analyses showed no cross reactions with Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Enterobacter aerogenes, Shigella and Campylobacter jejuni. The results for detection in real food samples showed that 1.3–1.9 CFU/g or 1.3–1.9 CFU/mL of Salmonella in contaminated chicken products and infant nutritional cereal could be detected after 2 h of enrichment. The same amount of Salmonella in contaminated milk could be detected after 4 h of enrichment. This tHDA-strip can be used for the rapid detection of Salmonella in food samples and is particularly suitable for use in areas with limited equipment.
Co-reporter:Xingxing He;Fuyuan Zhang;Lin Zhang;Qiang Zhang;Guozhen Fang;Jifeng Liu;Shuqiu Zhang
Journal of Materials Chemistry B 2017 vol. 5(Issue 26) pp:5225-5233
Publication Date(Web):2017/07/04
DOI:10.1039/C7TB01426K
The remarkable catalytic properties of enzymes contribute to their unique 3D structures and arrangement of amino acid residues, which provide a blueprint for the design of artificial enzymes. Here, a series of peptide catalysts (PCs) that mimic the unique orientation and function of β-glycosyl hydrolases were designed. Transmission electron microscopy (TEM), fluorescence analysis, circular dichroism spectroscopy, X-ray diffraction and computational modeling were used to investigate and compare the relationship of the fibrinous structure of PCs with its glycoside hydrolysis activity. These results indicated that the catalytic activity of PCs was not only related to their amyloid-like structures, but it can also be influenced by the site, species, molecular arrangement and steric hindrance of the amino acid sequence. What's more, this is the first report on peptide-inspired catalysts that mimic the natural cellobiose hydrolases. All this provided insights into the potential use of peptide nanoenzymes in the generation of efficient artificial enzymes.
Co-reporter:Rui Tong;Xiaopeng Hu;Guozhen Fang;Shiming Sun;Jingmin Liu
RSC Advances (2011-Present) 2017 vol. 7(Issue 79) pp:49969-49974
Publication Date(Web):2017/10/26
DOI:10.1039/C7RA07634G
A reliable upconversion (UC) material assembled from Au@Ag (UC@SiO2@Au@Ag), as the substrate, was firstly employed to detect hexamethylenetetramine (HMT) in bean vermicelli by surface enhanced Raman spectroscopy (SERS). In this substrate, UC can convert near-infrared (NIR) light into visible light to promote localized surface plasmon resonance (LSPR) of noble metal nanoparticles to enhance the SERS signal. According to optimized synthesis conditions, the SERS substrate was obtained and evaluated. The substrate shows uniformity with RSD of 7.05% and 7.37% for the Raman vibrations at ∼780 cm−1 and ∼1043 cm−1 respectively, and sensitivity with detection limits of 1 mg L−1 for HMT. Based on the better sensitivity of this method, the artificially positive samples have been detected.
Co-reporter:Gaoshuang Hu;Wei Sheng;Shijie Li;Yan Zhang;Junping Wang
RSC Advances (2011-Present) 2017 vol. 7(Issue 49) pp:31123-31128
Publication Date(Web):2017/06/13
DOI:10.1039/C7RA01753G
A novel multiplex fluorescence quenching immune chromatographic strip (FQICS), using quantum dots (QDs) as a fluorescence donor, was proposed to screen sulfonamide (SA) and fluoroquinolone (FQ) residues in chicken samples, simultaneously. The principle of the proposed FQICS is on the basis of the fluorescence quenching effect, and colloidal gold was used as the fluorescence quencher. The limit of detection (LOD) in standard solution was 3 ng mL−1 and 0.6 ng mL−1 for sulfaquinoxaline (SQX) and norfloxacin (NOR), respectively, through visual detection using UV. For specificity analysis, results obtained indicated that this established method could be applied in broad-spectrum detection of SAs and FQs. Then the proposed FQICS was successfully applied in semiquantitative analysis of SQX (30 μg kg−1) and NOR (6 μg kg−1) in spiked chicken samples. The results obtained using the strips showed great agreement with those obtained using an ELISA kit, which indicates the good accuracy of the strips. As a conclusion, the proposed FQICS with a signal “turn-on” mode provides a suitable immunoassay for rapid, sensitive and simultaneous screening of SAs and FQs in chicken samples on-site.
Co-reporter:Xingxing He;Fuyuan Zhang;Jifeng Liu;Guozhen Fang
Nanoscale (2009-Present) 2017 vol. 9(Issue 45) pp:18066-18074
Publication Date(Web):2017/11/23
DOI:10.1039/C7NR06525F
Cellulose, an impressive potential sustainable fuel, is difficult to hydrolyze because of the protection of β-1,4-glycosidic bonds through the tight hydrogen bonding network. In this study, homogenous graphene oxide (GO)-peptide nanofiber hybrid hydrogels (GO-PNFs) were designed as a β-glycosyl hydrolase mimetic to achieve efficient degradation of cellobiose and cellopentaose. For comparison, free peptides, graphene oxide mixed with free peptides (GO-peptdies) and self-assembled peptide nanofibers (PNFs) were also studied for their activity as a hydrolase mimetics for degradation of cellobiose. Among these materials, GO-PNFs showed the highest hydrolysis activity. Transmission electron microscopy, atomic force microscopy, fluorescence analysis, circular dichroism spectroscopies, X-ray diffraction, Raman spectra and computational modeling were used to interpret the difference in activity mechanism in these artificially designed enzymes. These investigations suggested that high catalytic performance of GO-PNFs toward cellobiose and cellopentaose hydrolysis could be attributed to the formation of nanofiber structures of peptides, optimal molecular conformation and less steric hindrance to access the substrate. More importantly, GO not only served as a platform for attaching PNFs, but also created a hydrophobic microenvironment and facilitated proton transfer, an essential step in catalytic hydrolysis, thus enhancing catalytic activity. All these provided insights into the potential use of peptides and GO hybrid composite nanoenzymes in efficient cellulose hydrolysis.
Co-reporter:Xiaopeng Hu;Guozhen Fang;Ailing Han;Jingmin Liu
Analytical Methods (2009-Present) 2017 vol. 9(Issue 14) pp:2177-2182
Publication Date(Web):2017/04/06
DOI:10.1039/C7AY00151G
A novel multidisciplinary method for the detection of Pericarpium papaveris in hot pot condiments was put forward using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) with thin-layer chromatography and surface enhanced Raman spectroscopy (TLC-SERS). In this study, papaverine and noscapine were detected to indirectly identify Pericarpium papaveris in hot pot condiments, because they are the major components of pericarpium. The feasibility of using the QuEChERS method for detection using TLC-SERS was evaluated. Derivative spectra (the first derivative spectra and the second derivative spectra) were used to reduce the interference resulting from the QuEChERS process and TLC-SERS via a support vector machine (based on particle swarm optimization). The limits of detection for noscapine and papaverine in hot pot condiments were 3 mg kg−1 and 0.5 mg kg−1, respectively. Employing this proposed strategy, the analytes in complex matrices were detected rapidly and sensitively. Moreover, it can be widely applied to detect the analytes in food.
Co-reporter:Shujun Wang, Jinrong Wang, Shaokang Wang, Shuo Wang
Food Hydrocolloids 2017 Volume 62(Volume 62) pp:
Publication Date(Web):1 January 2017
DOI:10.1016/j.foodhyd.2016.08.006
•Starches with different polymorphs respond differently to annealing treatment.•Annealing had little effect on structures of wheat, potato and yam starches.•Annealing at 50 °C resulted in a continuously increasing viscosity of potato starch.•Ordering of amorphous regions was responsible for the increased viscosity of starch.The effect of annealing treatments at different temperatures on structural and functional properties of wheat, potato, and yam starches was investigated. Annealing had little effect on the long- and short-range ordered structures of three starches, except for the annealing of wheat starch at 50 °C. Annealing increased the gelatinization temperatures of three starches, but had little effect on the enthalpy changes. Annealing at 30 and 40 °C increased the overall paste viscosity of wheat starch, while the treatment at 50 °C reduced the paste viscosity substantially. There was a continuous increase in paste viscosity of potato starch after annealing at 50 °C during the whole RVA (rapid viscosity analyser) testing. The increases in gelatinization temperatures and paste viscosities were attributed to the increased ordering of starch chains in amorphous regions. Our results showed that annealing is an effective method to increase the paste viscosity of starch, which is very important for the application of annealed starch.Download high-res image (316KB)Download full-size image
Co-reporter:Guozhen Fang, Yukun Yang, Huidan Zhu, Ying Qi, Jingmin Liu, Huilin Liu, Shuo Wang
Sensors and Actuators B: Chemical 2017 Volume 251(Volume 251) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.snb.2017.05.094
•A MIP-QCM sensor was developed for rapid detection of metolcarb.•The MIP showed good selective affinity towards the target molecule.•The MIP-QCM sensor exhibited high selectivity towards metolcarb.•This work provided a promising method for metolcarb analysis in food matrix.A strategy for rapid detection of metolcarb was reported based on molecularly imprinted quartz crystal microbalance (QCM) sensor. The molecularly imprinted ploymer (MIP) was prepared and used as the molecular recognition element of the QCM sensor. The adsorption properties of the prepared MIP were evaluated by static and dynamic adsorption test and Scatchard analysis, demonstrating high affinity and homogeneous imprinting sites towards metolcarb. Through a series of evaluation experiments, the proposed MIP-QCM sensor displayed a linear relationship between frequency shift and the concentration of metolcarb ranging from 5 μg L−1 to 70 μg L−1 with a low detection limit of 2.309 μg L−1 (S/N = 3). The proposed sensor exhibited high selectivity towards target metolcarb compared with its structural analogs, and was applied to different food samples with satisfactory recoveries (85.4–95.5%). The above results were in accordance with those obtained by high-performance liquid chromatography, indicating that the prepared MIP-QCM sensor has high accuracy and precision for metolcarb analysis in food matrix.
Co-reporter:Yayu Yang;Ailing Han;Ruixue Li;Guozhen Fang;Jifeng Liu
Analyst (1876-Present) 2017 vol. 142(Issue 23) pp:4486-4493
Publication Date(Web):2017/11/20
DOI:10.1039/C7AN01348E
As a promising fluorescent material, gold nanoclusters (Au NCs) have been used for biosensing and imaging. In metal ion sensing, the fluorescence of Au NCs is usually quenched in the presence of ions, but the reaction mechanism has not been clarified. In this work, mercaptan acids (3-mercaptopropanoic acid (3-MPA), 6-mercaptohexanoic acid (6-MHA), 11-mercaptoundecanoic acid (11-MUA) and 16-mercaptohexadecanoic acid (16-MHA)) were used as reductants and ligands to synthesize fluorescent Au NCs. The Au NCs had a core containing 18 atoms capped by 18 (3-MPA) or 10 (6-MHA, 11-MUA, 16-MHA) ligand molecules. The Au NCs prepared in this work had higher fluorescence quantum yields than those reported previously and the fluorescence showed a red-shift when varying the chain length of the mercaptan acids. It was found that in presence of ions (Mo(VI), Hg(II)), the fluorescence of the Au NCs is dependent upon the ligands. The Au NCs with 3-MPA and 6-MHA ligands were sensitive to Mo(VI) and Hg(II), while the Au NCs capped with 11-MUA and 16-MHA ligands were not sensitive to the ions. Various characterization techniques, including transmission electron microscopy, matrix-assisted laser-desorption ionization time of flight mass spectrometry, X-ray photoelectron spectroscopy, UV-Vis absorption spectroscopy and thermogravimetric analysis, were used to investigate the components and electronic structure of the clusters, as well as the emission and excitation properties before and after the reaction with metal ions. The structure of the Au NCs after the reaction with Mo(VI) and Hg(II) was also studied. It was found that Mo(VI) and Hg(II) both reacted with the gold atoms at the core site, but the reaction mechanisms were different.
Co-reporter:Meng Dang;Qiliang Deng;Guozhen Fang;Dongdong Zhang;Jingmin Liu
Journal of Materials Chemistry B 2017 vol. 5(Issue 31) pp:6339-6347
Publication Date(Web):2017/08/09
DOI:10.1039/C7TB01234A
A series of anionic polymeric ionic liquid (PIL) materials with high adsorption capacities toward proteins were developed using a 2-acrylamido-2-methylpropane sulfonic acid imidazole derivative ([AMPS][RIm]) (R: –H, –C6H5, or –(CH2)3CH3) as the functional monomer. An anionic polymeric ionic liquid monomer (ILM) containing imidazole cations modified with alkyl derivatives (butyl or phenyl groups) and sulfonic group-functionalized anions was chosen as the only monomer to prepare materials for protein adsorption. The resultant anionic PIL materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The adsorption behaviors of the obtained anionic PIL materials toward proteins was evaluated. The results indicated that the anionic PILs material showed superior adsorption for different proteins at different pH values: ovotransferrin (OVT, 861.5 mg g−1) and bovine serum albumin (BSA, 842.2 mg g−1) at pH 4.0; bovine hemoglobin (BHb, 983.4 mg g−1) and cytochrome c (Cytc, 882.9 mg g−1) at pH 7.0; and casein (605.2 mg g−1) at pH 8.0. The feasibility of the resultant material for separating BHb from real bovine blood has also been demonstrated. The convenient preparation of anionic PIL materials and ultra-high adsorption capacity toward proteins predicted its attractive and potential broad applications in proteomics, medical diagnosis, and sensors.
Co-reporter:Jing-Min Liu, Yao-Yao Liu, Dong-Dong Zhang, Guo-Zhen Fang, and Shuo Wang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 44) pp:29939
Publication Date(Web):October 19, 2016
DOI:10.1021/acsami.6b09580
The rise of multimodal nanoprobes has promoted the development of new methods to explore multiple molecular targets simultaneously or to combine various bioimaging tools in one assay to more clearly delineate localization and expression of biomarkers. Persistent luminescence nanophosphors (PLNPs) have been qualified as a promising contrast agent for in vivo imaging. The easy surface modification and proper nanostructure design strategy would favor the fabrication of PLNP-based multifunctional nanoprobes for biological application. In this paper, we have proposed novel multifunctional core–shell nanomaterials, applying the Mn4+ and Ge4+ co-doped gadolinium aluminate (GdAlO3:Mn4+,Ge4+) PLNPs as the near-infrared persistent luminescence emission center and introducing the gold nanoshell coated on the PLNPs to enhance the luminescence efficiency via plasmon resonance. Our developed core–shell nanoprobes have demonstrated the excellent features of ultrabrightness, superlong afterglow, good monodispersity, low toxicity, and excellent biocompatibility. The well-characterized nanoprobes have been utilized for trimodality in vivo imaging, with near-infrared persistent luminescence for optical imaging, Gd element for magnetic resonance imaging, and Au element for computed tomography imaging.Keywords: bioimaging; gold nanoshell; persistent luminescence; plasmon enhancement; trimodality
Co-reporter:Yang Lu, Mengjuan Li, Minling Ding, Guozhen Liu, Yan Zhang, Shuo Wang
Journal of Electroanalytical Chemistry 2016 Volume 779() pp:34-38
Publication Date(Web):15 October 2016
DOI:10.1016/j.jelechem.2016.05.039
Antibodies against bisphenol-A (Ab ∝ BPA) and BPA-butyric-horseradish peroxidase (HRP) were generated and utilised to fabricate a gold-nanoparticles (AuNPs)-based electrochemical biosensor for the detection of BPA. The glassy carbon electrode surface was modified with AuNPs via chronoamperometry (CA) to increase the surface-to-volume ratio and provide a robust sensing surface. The Abs ∝ BPA were generated and immobilized on the AuNP-modified electrode using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) method with thioctic acid as linker. The assay was conducted using competition and displacement formats. Then, the working electrode, counter electrode and reference electrode were placed in a phosphate-buffered saline (PBS) containing ferrocenemethanol (FcOH) and H2O2. Sensitivity data were interpreted using the same sensor surface, enabling a direct comparison between the reduction currents of the oxidized form of ferrocenemethanol in the two assay formats which indicated the concentration of BPA bound to Ab ∝ BPA. Starting from a pre-blocked sensor surface, the competition assay was completed in 1 h and the displacement assay took 2 h. The limit of detection (LOD) in competition assay and displacement assay were 12.35 μg L− 1 and 4.11 μg L− 1, respectively.
Co-reporter:Yuchen Gu, Yanling Guo, Haijie Li, Rina Su, Kejin Sun, Qiliang Deng and Shuo Wang
RSC Advances 2016 vol. 6(Issue 48) pp:41707-41713
Publication Date(Web):11 Apr 2016
DOI:10.1039/C6RA00464D
The preparation of materials capable of the selective enrichment of phosphorylated peptides is important to phosphoproteome study. Herein, a new poly(guanidinium ionic liquid)s material was prepared using a polymerizable guanidinium ionic liquids as the functional monomer. A large number of guanidinium groups on the surface of the materials may interact with the phosphorylated peptides by a non-covalent bond such as a hydrogen bond and ionic bond. The feasibility of the resulting materials for the enrichment of phosphopeptides was investigated further using standard proteins, protein mixture and nonfat milk as samples. The resulting materials showed excellent enrichment property for phosphopeptides such as high selectivity (phosphopeptides/non-phosphopeptides at a molar ratio of 1:1000) and extremely high detection sensitivity (4.0 × 10−11 M). The excellent practical utility of the resulting materials for phosphopeptides enrichment was also demonstrated by enriching the phosphopeptides from tryptic digest of nonfat milk.
Co-reporter:Wei Sheng, Congcong Sun, Guozhen Fang, Xuening Wu, Gaoshuang Hu, Yan Zhang, and Shuo Wang
Journal of Agricultural and Food Chemistry 2016 Volume 64(Issue 46) pp:8944-8949
Publication Date(Web):November 5, 2016
DOI:10.1021/acs.jafc.6b04422
A competitive indirect enzyme-linked immunosorbent assay (ciELISA) using a polyclonal antibody was developed to detect tyramine in meat and seafood. This ciELISA had a 50% inhibition concentration (IC50) of 0.20 mg/L and a limit of detection (LOD) of 0.02 mg/L and showed no cross-reactivity with tyrosine or other biogenic amines. The average recoveries of tyramine from spiked samples for this ciELISA ranged from 85.6 to 102.6%, and the results exhibited good correlation with high-performance liquid chromatography (HPLC) results. The LOD of this assay for tyramine in meat and seafood samples was 1.20 mg/kg. The ciELISA was successfully applied to detect tyramine in positive fish samples, and the results were validated by HPLC to be reliable. The developed ciELISA allows for the rapid, specific, and accurate detection of tyramine in meat and seafood samples, and it could be a potentially useful tool for the evaluation of the freshness of protein-rich foods.Keywords: detection; ELISA; freshness; meat; seafood; tyramine;
Co-reporter:Xin-jun Du, Xiao-nan Zhou, Ping Li, Wei Sheng, Frédéric Ducancel, and Shuo Wang
Journal of Agricultural and Food Chemistry 2016 Volume 64(Issue 14) pp:2971-2979
Publication Date(Web):March 22, 2016
DOI:10.1021/acs.jafc.6b00639
Specific antibodies are essential for the immune detection of small molecule contaminants. In the present study, the heavy and light variable regions (VH and VL) of the immunoglobulin genes from a hybridoma secreting a chloramphenicol (CAP)-specific monoclonal antibody (mAb) were cloned and sequenced. In addition, the light and heavy chains obtained from the monoclonal antibody were separated using SDS–PAGE and analyzed using Orbitrap mass spectrometry. The results of DNA sequencing and mass spectrometry analysis were compared, and the VH and VL chains specific for CAP were determined and used to construct a single-chain variable fragment (scFv). This fragment was recombinantly expressed as a soluble scFv-alkaline phosphatase fusion protein and used to develop a direct competitive ELISA. Compared with the parent mAb, scFv exhibits lower sensitivity but better food matrix resistance. This work highlights the application of engineered antibodies for CAP detection.
Co-reporter:Gaoshuang Hu, Wei Sheng, Yan Zhang, Junping Wang, Xuening Wu, and Shuo Wang
Journal of Agricultural and Food Chemistry 2016 Volume 64(Issue 19) pp:3908-3915
Publication Date(Web):May 2, 2016
DOI:10.1021/acs.jafc.6b01497
A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L–1 in buffer and 0.5 μg kg–1 in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24–25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods.
Co-reporter:Kuo He, Xinjun Du, Wei Sheng, Xiaonan Zhou, Junping Wang, and Shuo Wang
Journal of Agricultural and Food Chemistry 2016 Volume 64(Issue 12) pp:2627-2634
Publication Date(Web):March 10, 2016
DOI:10.1021/acs.jafc.5b05882
The limited knowledge on the mechanism of interactions between small contaminants and the corresponding antibodies greatly inhibits the development of enzyme-linked immunosorbent assay methods. In this study, the crystal structure of a Fab fragment specific for ofloxacin was obtained. On the basis of the crystal characteristics, the modeling of the interactions between ofloxacin and the Fab revealed that TYR31 and HIS99 of the heavy chain and MET20 and GLN79 of the light chain formed a hydrophobic region and that SER52 and ALA97 of the heavy chain and TYR35 of the light chain formed a salt bridge and two hydrogen bonds for specific binding. The key roles of SER52 and ALA97 were further confirmed by site-directed mutation. A specificity analysis using 14 ofloxacin analogues indicates that the length of the bond formed between the piperazine ring and the antibody plays key roles in specific recognition. This work helps to clarify the mechanisms through which antibodies recognize small molecules and improve immune detection methods.
Co-reporter:Huaping Zhu, Shanshan Yang, Yan Zhang, Guozhen Fang and Shuo Wang
Analytical Methods 2016 vol. 8(Issue 18) pp:3747-3755
Publication Date(Web):29 Mar 2016
DOI:10.1039/C6AY00010J
Simultaneous detection of many kinds of biogenic amines (BAs) is difficult because they have diverse structures. A HPLC method was established suitably for the simultaneous detection of fifteen biogenic amines in four types of animal-derived food products. The biogenic amines were derivatized with dansyl chloride, purified by using a Waters Sep-Pak C18 then separated on an ODS-2 Hypersil C18 column with a binary system using gradient elution. The derivatives were detected using wavelengths of 350 and 480 nm for excitation and emission, respectively. The limit of detection (LOD) for BAs ranged from 0.002 to 0.03 mg kg−1 and the linearities of linear regression equations for fifteen biogenic amines were good (R2 between 0.9990 and 0.9999). The method was applied to detect BAs in pork, beef, carp and crucian carp. Recoveries ranged from 70.49 to 121.16% at three spiked levels (0.5, 1 and 2 mg kg−1), with RSDs in a range of 0.71–15.99%. Intra- and inter-day precisions (RSD%) were in a range of 0.30–4.60% and 4.62–14.97%, respectively. These data indicated that the established method was capable of simultaneous and precise quantitation of fifteen biogenic amines in animal-derived products of potential physiological importance for human health.
Co-reporter:Ting Guo, Qiliang Deng, Guozhen Fang, Dahai Gu, Yukun Yang, Shuo Wang
Biosensors and Bioelectronics 2016 Volume 79() pp:341-346
Publication Date(Web):15 May 2016
DOI:10.1016/j.bios.2015.12.040
•A novel fluorescence material based on UCNPs, MOFs and MIP was prepared.•The fluorescence material could recognition template with response to temperature.•UCNPs were introduced as fluorophores to provide fluorescent signal.•MOFs were introduced to increase the rate mass transfer and adsorption capacity.A novel fluorescence material with thermo-sensitive for the enrichment and sensing of protein was successfully prepared by combining molecular imprinting technology with upconversion nanoparticles (UCNPs) and metal-organic frameworks (MOFs). Herein, the UCNPs acted as signal reporter for composite materials because of its excellent fluorescence property and chemical stability. MOFs were introduced to molecularly imprinted polymer (MIP) due to its high specific surface area which increases the rate of mass transfer relative to that of traditional bulk MIP. The thermo-sensitive imprinted material which allows for swelling and shrinking with response to temperature changes was prepared by choosing Bovine hemoglobin (BHB) as the template, N-isopropyl acrylamide (NIPAAM) as the temperature-sensitive functional monomer and N,N-methylenebisacrylamide (MBA) as the cross-linker. The recognition characterizations of imprinted material-coated UCNPs/MOFs (UCNPs/MOFs/MIP) were evaluated, and the results showed that the fluorescence intensity of UCNPs/MOFs/MIP reduced gradually with the increase of BHB concentration. The fluorescence material was response to the temperature. The adsorption capacity was as much as 167.6 mg/g at 28 °C and 101.2 mg/g at 44 °C, which was higher than that of traditional MIP. Therefore, this new fluorescence material for enrichment and sensing protein is very promising for future applications.
Co-reporter:Ting Guo, Qiliang Deng, Guozhen Fang, Yaguang Yun, Yongjin Hu, Shuo Wang
Biosensors and Bioelectronics 2016 Volume 85() pp:596-602
Publication Date(Web):15 November 2016
DOI:10.1016/j.bios.2016.05.056
•A double responsive smart upconversion fluorescence sensing material for glycoprotein was prepared.•Upconversion nanoparticles (UCNPs) were introduced as fluorophores to provide fluorescent signal.•Graphene oxide (GQ) were utilized to increase the rate mass transfer and adsorption capacity.A novel strategy was developed to prepare double responsive smart upconversion fluorescence material for highly specific enrichment and sensing of glycoprotein. The novel double responsive smart sensing material was synthesized by choosing Horse radish peroxidase (HRP) as modal protein, the grapheme oxide (GO) as support material, upconversion nanoparticles (UCNPs) as fluorescence signal reporter, N-isopropyl acrylamide (NIPAAM) and 4-vinylphenylboronic acid (VPBA) as functional monomers. The structure and component of smart sensing material was investigated by transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared (FTIR), respectively. These results illustrated the smart sensing material was prepared successfully. The recognition characterizations of smart sensing material were evaluated, and results showed that the fluorescence intensity of smart sensing material was reduced gradually, as the concentration of protein increased, and the smart sensing material showed selective recognition for HRP among other proteins. Furthermore, the recognition ability of the smart sensing material for glycoprotein was regulated by controlling the pH value and temperature. Therefore, this strategy opens up new way to construct smart material for detection of glycoprotein.
Co-reporter:Bing Liu, Lingling Wang, Bei Tong, Yan Zhang, Wei Sheng, Mingfei Pan, Shuo Wang
Biosensors and Bioelectronics 2016 Volume 85() pp:337-342
Publication Date(Web):15 November 2016
DOI:10.1016/j.bios.2016.05.032
In this study, the three nanomaterials: colloidal gold, nanogold-polyaniline-nanogold microspheres (GPGs) and colloidal carbon were respectively labeled with the antibody against salbutamol (SAL). We aimed to develop immunochromatographic strips with these nanomaterial labels and determine their performance in visual detection of SAL. For the colloidal gold-based strip, the detection limit of SAL was 1.0 µg L−1 in standard solution and 5.0 µg kg−1 in meat samples. For the GPG- and colloidal carbon-based strips, the limit of detection was 2.0 µg L−1 in standard solution and 10 µg kg−1 in meat samples. The results obtained using the test strips were found to be highly consistent with those obtained using a commercial kit, indicating the high accuracy of these strips. The three strips were also found to be stable up to 18 weeks under laboratory conditions. In terms of sensitivity, the colloidal gold-based strip was slightly better than the other two. For the GPG- and colloidal carbon-based strips, the difference between the results obtained for different batches was small (high consistency), and the stability was much better than that of the colloidal gold-based one. Our results indicate that colloidal carbon can be used as a label in immunochromatographic tests; it can also help reduce the cost involved and scale-up the production. The use of immunochromatographic test strips labeled with colloidal carbon can be a rapid and inexpensive method for SAL assays in on-site applications.
Co-reporter:Guozhen Fang, Hao Wang, Yukun Yang, Guiyang Liu, Shuo Wang
Sensors and Actuators B: Chemical 2016 Volume 237() pp:239-246
Publication Date(Web):December 2016
DOI:10.1016/j.snb.2016.06.099
•A simple MIPs-QCM sensor was developed for trace patulin detection.•The novel MIPs was synthesized through sol-gel process.•The sensor showed good selective affinity, reproducibility and stability.•This work may provide a promising method for sensing applications.A simple quartz crystal microbalance (QCM) sensor based on a sol-gel molecularly imprinted polymer (MIP) film as the recognition element was developed for patulin (PAT) detection. The high adsorption capacity of the proposed MIP for PAT was demonstrated by Scatchard equation analysis. Through the evaluation, based on the QCM frequency change, the developed sensor exhibited a linear concentration range of PAT from 7.5 × 10−3 μg mL−1 to 6 × 10−2 μg mL−1 with a lower detection limit of 3.1 × 10−3 μg mL−1 (S/N = 3). The sensor showed good selective affinity for PAT (selectivity coefficient = 3.82) as well as good reproducibility and long-term stability. The developed sensor was tested on its ability to detect PAT in real samples through a spiking and recovery study with the recoveries ranging from 76.9% to 91.3% (RSDs < 8.4%). The good agreement results of the established MIP-QCM sensor and HPLC–MS method indicated that the developed method could accurately detect PAT in practical food samples.
Co-reporter:Xuan Huang, Junping Wang, Cuicui Liu, Ting Guo and Shuo Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 12) pp:2505-2515
Publication Date(Web):06 Feb 2015
DOI:10.1039/C4TB01899K
A novel rGR–TiO2–ZrO2 (rGTZ) composite nanosheet comprising graphene oxides, tetrabutyl titanate, and zirconium(IV) isopropoxide was synthesized using a simple sol–gel method and hydrothermal treatment. The excellent surface area of graphene and the specificity of TiO2 and ZrO2 toward phosphopeptides were integrated to form a composite with a high number of specific sites for the capture of phosphopeptides from complex biosamples. The average diameter of the nanoparticles that were loaded onto the flat graphene surface was 100 nm, according to a TEM analysis. The adsorption behaviors of the materials were evaluated using the Langmuir model equation, and the Qmax values of the commercial TiO2, GTZ, and rGTZ were calculated to be 373.1 mg g−1, 250.0 mg g−1 and 490.2 mg g−1. Beta-casein was applied as a standard protein to optimize the conditions for phosphopeptide enrichment. Different materials (GTZ and commercial TiO2) were used to demonstrate the superiority of the rGTZ composite nanosheet for capturing phosphopeptides from tryptic digests of β-casein under the optimized conditions. Various complex samples (α-casein, mixtures of β-casein and bovine serum albumin, which were used as examples of semi-complex samples, non-fat milk, and mouse organs) were exploited to evaluate the capabilities and efficiency of the rGTZ nanosheet composite. 1980 phosphopeptides from 1769 proteins from mouse brain and 577 phosphopeptides from 1267 proteins from mouse liver were identified by their enrichment in mouse brain and liver using rGTZ nanosheet composites.
Co-reporter:Cuicui Liu, Qiliang Deng, Guozhen Fang, Xuan Huang, Shuo Wang, and Jinsong He
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 36) pp:20430
Publication Date(Web):August 28, 2015
DOI:10.1021/acsami.5b07668
Currently, many types of affinity materials have been developed for the enrichment of glycoproteins potentially considered to be clinical biomarkers; however, they can not effectively distinguish between different glycoproteins and thus lack the functionality that may be the key to the diagnosis of specific diseases. In the present work, a novel interface-free 2D monolithic material has been developed for the separation of multiple types of glycoproteins, in which boronate-functionalized graphene acts as preconcentration segment and poly(guanidinium ionic liquid) acts as separation segment. The resultant 2D material was characterized by X-ray photoelectron spectroscopy, elemental analysis, and electroosmotic flow analysis to demonstrate successful modification at each step. The performance of this 2D material was evaluated by capillary electrochromatography and allowed the successful online concentration and separation of five standard glycoproteins. The high separation efficiency can be largely attributed to the good orthogonality of boronate-functionalized graphene monolith and poly(guanidinium ionic liquid) monolith.Keywords: glycoprotein; guanidinium ionic liquid; monolithic material; preconcentration and separation; two-dimensional
Co-reporter:Jinglin Yu, Shujun Wang, Jingrong Wang, Caili Li, Quanwei Xin, Wei Huang, Yan Zhang, Zhonghu He, Shuo Wang
Food Chemistry 2015 Volume 172() pp:504-514
Publication Date(Web):1 April 2015
DOI:10.1016/j.foodchem.2014.09.070
•Starches from different flour millstreams of hard and soft wheat were characterised.•Starches in hard wheat grains suffered more severe damage during milling.•Starches from reduction flour millstreams suffered more severe damage.•Milling did not disrupt the crystalline structure of starch granules.•Functionality and in vitro digestibility was altered in different way by milling.The properties of starch from different flour millstreams are very important for the production of specific flours used in different wheat-based food products. The present study aimed at characterising starches from different flour millstreams by Buhler laboratory mill and flour from Brabender senior mill. Damaged starch content increased from 3.4% to 15.7% and from 1.8% to 6.0% for flour from B1 to R3 millstream of Beijing 0045 and Zhongmai 175, respectively. Milling resulted in the fragmentation of starch granules, but did not induce significant changes in the relative crystallinity. Starches from different flour millstreams presented similar swelling power values. Except onset temperature of starches from Beijing 0045, no significant differences were observed in thermal transition parameters of starches from Beijing 0045 or Zhongmai 175. Pasting and in vitro digestion profiles of starches from different flour millstreams showed significant differences. This study showed that laboratory milling induces variable differences in functional properties without changing starch crystalline structure.
Co-reporter:Shujun Wang, Jinrong Wang, Wei Zhang, Caili Li, Jinglin Yu, Shuo Wang
Food Chemistry 2015 Volume 181() pp:43-50
Publication Date(Web):15 August 2015
DOI:10.1016/j.foodchem.2015.02.065
•Molecular order of starches from three waxy wheat varieties was characterized.•No significant differences were noted in molecular order of waxy wheat starches.•Small and in some cases significant differences observed in functional properties.•Waxy wheat starch is resistant to recrystallization under the stored conditions.Molecular order and functional properties of starch from three waxy wheat varieties grown in China were investigated by a combination of various technical analyses. The total starch content of the waxy wheat ranged between 54.1% and 55.0%, and the amylose content of the starch was between 0.71% and 1.63%. Average particle diameter of the three starches varied between 16.5 and 17.4 μm. Three waxy wheat starches presented the typical A-type X-ray diffraction pattern, with relative crystallinity between 38.7% and 40.0%. No significant differences were observed in relative crystallinity, IR ratios of 1047/1022 cm−1 and 1022/995 cm−1, and FWHH of the band at 480 cm−1, indicating the similarity in long-range order of crystallites and short-range order of double helices of three starch granules. Small differences were observed in swelling power, gelatinization parameters, pasting viscosities, and in vitro enzymatic digestibility of three waxy wheat starches. Under the stored condition, no retrogradation occurred for three waxy wheat starches.
Co-reporter:Xin-jun Du, Ran Han, Ping Li, Shuo Wang
Journal of Proteomics 2015 Volume 128() pp:344-351
Publication Date(Web):14 October 2015
DOI:10.1016/j.jprot.2015.08.013
•The virulence of 42 Cronobacter sakazakii strains was examined by oral gavage.•Four groups of strains suitable for comparative 2-DE analysis were identified.•At least 11 putative virulence-related proteins were identified by MALDI-TOF/TOF.•Real-time PCR verified the differences in putative virulence-related factors.Cronobacter is a genus of widespread, opportunistic, foodborne pathogens that can result in serious illnesses in at-risk infants because of their immature immunity and high dependence on powdered formula, which is one of the foods most often contaminated by this pathogen. However, limited information is available regarding the pathogenesis and the specific virulence factors of this species. In this study, the virulences of 42 Cronobacter sakazakii isolates were analyzed by infecting neonatal SD rats. A comparison of the typing patterns of the isolates enabled groups with close relationships but that exhibited distinct pathogenesis to be identified. Among these groups, 2 strains belonging to the same group but showing distinct virulences were selected, and 2-DE was applied to identify differentially expressed proteins, focusing on virulence-related proteins. A total of 111 protein spots were identified using matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS), and 89 were successfully identified. Further analysis suggested that at least 11 of these proteins may be involved in the pathogenesis of this pathogen. Real-time PCR was carried out to further confirm the differential expression pattern of the genes, and the results indicated that the mRNA expression levels were consistent with the protein expression levels.Biological significanceThe virulence factors and pathogenesis of Cronobacter are largely unknown. In combination with animal toxicological experiments and subtyping results of C. sakazakii, comparative proteomics analysis was performed to comprehensively evaluate the differentially expressed proteins of two isolates that exhibited distinct virulence but were closely related. These procedures made it possible to identify the virulence-related of factors of Cronobacter. Among the 89 total identified proteins, at least 11 show virulence-related potential. This work provides comprehensive candidates for the further investigation of the pathogenesis of Cronobacter.
Co-reporter:Kejin Sun, Qiliang Deng, Ting Guo, Rina Su, Yuchen Gu and Shuo Wang
RSC Advances 2015 vol. 5(Issue 114) pp:94084-94090
Publication Date(Web):20 Oct 2015
DOI:10.1039/C5RA18316B
In this study, a sensitive and efficient approach was developed for the determination of melamine (MEL) based on the combination of molecularly imprinted polymers (MIPs) with a synthesized fluorescent chemosensor. The fluorescent chemosensor was designed ingeniously based on the open loop of a rhodamine B (RB) derivative. The MIPs were prepared by precipitation polymerization with MEL as a template, nano-CaCO3 as a porogenic agent, ethylene glycol dimethacrylate as a crosslinking agent and methacrylic acid as a functional monomer. The specific recognition ability of the MIPs was investigated by static adsorption, kinetic adsorption, and selective and competitive adsorption, respectively. The resultant materials showed an outstanding affinity and selectivity to MEL. An imprinting factor of 3.072 could be obtained. The fluorescence intensity of the chemosensor displayed an outstanding linear relationship to the concentration of MEL in the range of 6.25 × 10−4–8 × 10−2 mmol L−1. The limit of detection (LOD) was found to be 1.55 × 10−4 mmol L−1. The recovery for MEL was in the range of 86.48–89.12% for milk samples, with RSDs ranging from 3.18 to 4.91%. The proposed approach was successfully applied to determine MEL in milk samples.
Co-reporter:Xuan Huang, Junping Wang, Junying Wang, Cuicui Liu and Shuo Wang
RSC Advances 2015 vol. 5(Issue 109) pp:89644-89651
Publication Date(Web):16 Oct 2015
DOI:10.1039/C5RA17471F
The reversible phosphorylation of proteins plays a crucial role in many regulatory processes. During the last decade, there has been considerable interest in the development of new methods for the identification of phosphorylation sites to allow for the comprehensive analysis of protein phosphorylation processes. However, the development of sensitive methods for the detection of trace quantities of phosphopeptides remains a significant challenge. In this study, we have prepared a novel graphene–hafnium oxide composite (GHOC) capable of enriching phosphopeptides and its application for the enrichment of phosphopeptides prior to their analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI – TOF/MS). The GHOC was prepared in a facile step using a hydrothermal reaction. The surface morphology of the resultant materials was analyzed in its compound-bound form by TEM, SAED and XRD. According to theses results, the GHOC had an increased surface area resulting from the template of graphene and the modification of hafnium oxide which possess high specificity toward phosphopeptides. Several complex samples (e.g. α- and β-casein, mixtures of β-casein and bovine serum albumin, and nonfat milk tryptic digest) were used to test the enrichment capability of the GHOC, and the results demonstrated that this material exhibited better selectivity towards mono- and multi-phosphorylated peptides compared with the graphene–TiO2 composite (GTOC) and graphene–ZrO2 composite (GZOC). Furthermore, MALDI-TOF/MS experiments revealed no interference from nonphosphopeptides. The results demonstrate that our newly developed GHOC shows high specificity for the enrichment of phosphopeptides from biological samples and could therefore be applied in the field of phosphoproteomics.
Co-reporter:Jing-Min Liu, Cui-Cui Liu, Guo-Zhen Fang and Shuo Wang
RSC Advances 2015 vol. 5(Issue 72) pp:58713-58726
Publication Date(Web):26 Jun 2015
DOI:10.1039/C5RA10348G
Ion Chromatography (IC) has undergone a tremendous development and can be regarded today as one of the most versatile analytical methods for all kinds of ionic compounds. The IC technique offers an enormous range of possibilities for the selection of stationary and mobile phases, fabrication of novel separation modes, and hyphenation with different detection techniques, which has made IC eminently suitable for the rapid and simultaneous determination of numerous inorganic and organic anions and cations. In this paper, firstly, a general overview of the IC principle, including the IC methodology, development history, separation mechanism, apparatus and procedure, and application, is given as an introduction of this technology. Secondly, the significant role of sample preparation for IC is discussed, and various IC sample preparation methods are summarized. Finally, the currently practiced advanced IC techniques for complicated samples, critical analytical requirements and unique application are presented, which mainly focus on the two-dimensional IC technique (2D-IC), hyphenation technique of IC with mass spectrometry (IC-MS) and capillary IC technique (CIC).
Co-reporter:Ling-Jie Kong, Ming-Fei Pan, Guo-Zhen Fang, Xin-lei He, Yin-qiang Xia and Shuo Wang
RSC Advances 2015 vol. 5(Issue 15) pp:11498-11505
Publication Date(Web):09 Jan 2015
DOI:10.1039/C4RA13554G
A molecularly imprinted electrochemical sensor for metolcarb (MTMC) detection was designed and constructed by electropolymerizing a poly-o-aminophenol (PoAP) membrane in the presence of MTMC after the modification of a composite that consisted of polypyrrole (PPY), functionalized multiwalled carbon nanotubes (MWNTs) and binuclear phthalocyanine cobalt(II) sulfonate (BiCoPc) on a glassy carbon electrode (GCE) surface. The modified electrodes were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The molecularly imprinted based sensor had a good binding ability toward MTMC upon measuring the variation of the amperometric response of the oxidation–reduction probe, K3Fe(CN)6. The relative peak current response was found to be proportional to the concentration of MTMC in the range of 1.0 × 10−8 to 0.6 × 10−6 mol L−1 with a detection limit of 7.88 × 10−9 mol L−1 (S/N = 3). This desirable sensitivity may be attributed to the presence of the PPY–MWNTs–BiCoPc composite layer, which enhanced the electrode surface area and amplified the current signal. The sensor showed good selective affinity toward MTMC, compared with similar molecules, with good reproducibility and long-term stability. The prepared sensor was successfully applied to the determination of the MTMC residue in spiked vegetable samples with satisfactory recoveries ranging from 88.8% to 93.3%.
Co-reporter:Guozhen Fang, Qinghui Lv, Cuicui Liu, Miaomiao Huo and Shuo Wang
Analytical Methods 2015 vol. 7(Issue 20) pp:8617-8625
Publication Date(Web):08 Sep 2015
DOI:10.1039/C5AY02021B
Speciation analysis of arsenic (As) and selenium (Se) in foods is of great significance for human health. In this paper, a novel ionic liquid improved reversed phase high performance liquid chromatography (RP-HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) method was developed for the simultaneous determination of six As species and four Se species. To enhance the detection sensitivity, the RP-HPLC-ICP-MS determination conditions were systematically optimized. Under the optimal conditions, good linearity ranging from 2.5 to 400 μg L−1 was obtained. The limits of detection (LODs) were 0.34–0.86 μg L−1 for the As species and 0.94–1.52 μg L−1 for the Se species. The recoveries of the As and Se species in animal/plant-derived samples (pork, chicken, rice and wheat) were in the range of 71.5–107.5% and 70.2–123.4%, respectively. These results demonstrated that the current method is promising for the accurate quantification of the As and Se species in foods.
Co-reporter:Cuicui Liu;Xue Feng;Hailong Qian;Guozhen Fang
Food Analytical Methods 2015 Volume 8( Issue 3) pp:596-603
Publication Date(Web):2015 March
DOI:10.1007/s12161-014-9936-1
A simple and sensitive capillary electrophoresis immunoassay method with laser-induced fluorescence detector was developed for the determination of norfloxacin in food samples. The assay was based on the competitive immunoreaction between fluorescein isothiocyanate-labeled norfloxacin tracer and free norfloxacin with a limited amount of antinorfloxacin antibody. In this study, the experimental parameters affecting the norfloxacin determination were systematically optimized including incubation time, buffer pH and concentration, and separation voltage. Under the optimal conditions, norfloxacin could be accurately quantified within 3 min using Na2B4O7/NaH2PO4 buffer (30 mmol/L, pH 8.0) for background electrolyte and 25 kV for the separation voltage. The linear range of the method was 0.08–50 μg/L with a detection limit of 0.005 μg/L. The relative standard deviations for migration time and peak area of the immunocomplex were 0.17 % (intraday) and 3.46 % (intraday), respectively. The proposed method has been further applied to the determination of norfloxacin in milk, chicken, pork, and fish samples, exhibiting satisfactory recovery and sensitivity. These results indicated that the proposed method might serve as an efficient tool for the selective determination of norfloxacin in food samples.
Co-reporter:Yukun Yang, Yaoyu Cao, Xiaomin Wang, Guozhen Fang, Shuo Wang
Biosensors and Bioelectronics 2015 Volume 64() pp:247-254
Publication Date(Web):15 February 2015
DOI:10.1016/j.bios.2014.09.009
•A three-dimensional molecularly imprinted electrochemical sensor had been established.•PB-CMK-3 hybrid acted as both the low-potential redox mediator and electron transfer facilitator.•Ultrasensitive, specific quantification of metolcarb had been achieved.•The construction route may provide a guideline for non-electroactive analytes determination.•It may contribute to the construction of electrochemical sensor with desirable 3D structure.In this work, we presented a three-dimensional (3D) molecularly imprinted electrochemical sensor (MIECS) with novel strategy for ultrasensitive and specific quantification of metolcarb based on prussian blue (PB) mediated amplification combined with signal enhancement of ordered mesoporous carbon. The molecularly imprinted polymers were synthesized by electrochemically induced redox polymerization of para aminobenzoic acid (p-ABA) in the presence of template metolcarb. Ordered mesoporous carbon material (CMK-3) was introduced to enhance the electrochemical response by improving the structure of the modified electrodes and facilitating charge transfer processes of PB which was used as an inherent electrochemical active probe. The modification process for the working electrodes of the MIECS was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV), and several important parameters controlling the performance of the MIECS were investigated and optimized in detail. The MIECS with 3D structure had the advantages of ease of preparation, high porous surface structure, speedy response, ultrasensitivity, selectivity, reliable stability, good reproducibility and repeatability. Under the optimal conditions, the MIECS offered an excellent current response for metolcarb in the linear response range of 5.0×10−10–1.0×10−4 mol L−1 and the limit of detection (LOD) was calculated to be 9.3×10−11 mol L−1 (S/N=3). The proposed MIECS has been successfully applied for the determination of metolcarb in real samples with satisfactory recoveries. Furthermore, the construction route of this ultrasensitive 3D MIECS may provide a guideline for the determination of non-electroactive analytes in environmental control and food safety.
Co-reporter:Cuicui Liu;Shaoyuan He;Kun Shen;Xue Feng;Guozhen Fang
Food Analytical Methods 2015 Volume 8( Issue 7) pp:1785-1793
Publication Date(Web):2015 August
DOI:10.1007/s12161-014-0061-y
A novel l-cysteine functionalized silica gel adsorbent (SG-Cys) was successfully synthesized and characterized by Fourier transform infrared (FTIR) spectra and elemental analysis. An efficient method for simultaneous determination of heavy metals [V (V), Cr (VI), Cu (II), As (V), Cd (II), and Pb (II)] was developed by inductively coupled plasma-mass spectrometry (ICP-MS) coupled with pre-concentration with the prepared SG-Cys adsorbent. The experimental parameters, including the solution pH, sample flow rate, eluent volume, eluent type, and concentration, have been systematically optimized to obtain higher enrichment factors of target ions. Under the optimum conditions, the enrichment factors of V (V), Cr (VI), Cu (II), As (V), Cd (II), and Pb (II) reached 123, 100, 86, 106, 97, and 94, respectively, and the detection limits were as low as 1.8–3.7 ng L−1. The proposed method has been applied to the determination of trace heavy metals in water, rice, wheat, corn, and tea samples, which exhibited a satisfactory recovery in the range of 90.6–106.0 %.
Co-reporter:Qiliang Deng, Jianhua Wu, Yang Chen, Zhijun Zhang, Yang Wang, Guozhen Fang, Shuo Wang and Yukui Zhang
Journal of Materials Chemistry A 2014 vol. 2(Issue 8) pp:1048-1058
Publication Date(Web):06 Dec 2013
DOI:10.1039/C3TB21540G
Phosphorylation of protein regulates nearly all biological processes in nature. The development of enrichment techniques for phosphorylated proteins is vital to systematic identification and characterization of phosphoproteins. Here, a general strategy for highly efficient capture of intact phosphorylated proteins from protein mixtures has been developed by using guanidine functionalized superparamagnetic microspheres (denoted as Fe3O4@SiO2@GDN). The Fe3O4@SiO2@GDN was prepared by modifying Fe3O4@SiO2 with 3-guanidopropyl triethoxysilane as a functionalization monomer. The resulting materials could specifically and selectively recognize phosphoproteins and showed high binding capacities for model phosphoproteins (78.8 mg g−1 for ovalbumin (OVA) and 59.6 mg g−1 for β-casein (β-Cas), respectively). The feasibility of the resulting material for phosphoprotein enrichment has also been demonstrated by selectively binding and capturing phosphoproteins from complex protein mixtures and real samples (milk, egg, and tissue protein extract from a mouse liver), respectively. In addition, the selective enrichment of phosphopeptides has also been investigated. The proposed technique showed application potential for phosphoprotein and phosphopeptide enrichment.
Co-reporter:Cuicui Liu, Qiliang Deng, Guozhen Fang, Xuan Huang and Shuo Wang
Journal of Materials Chemistry A 2014 vol. 2(Issue 32) pp:5229-5237
Publication Date(Web):16 Jun 2014
DOI:10.1039/C4TB00663A
Glycoproteins, as low-abundance proteins in organisms, play a critical role in numerous biological processes such as signal transduction, cell differentiation, cellular adhesion, immune defense and embryonic development. Thus, the development of enrichment techniques for glycoproteins is of great importance. In this study, a thiol graphene (TG) doped poly[ionic liquid (ViOcIm+Cl−)] boronate affinity monolithic material was prepared in a single step. The recognition property of the resulting material was evaluated by capillary electrochromatography. The results indicated that the affinity material exhibited specific capture toward cis-diol-containing catechol and glycoproteins at buffer pH as low as 4.0, showing wide pH applications. The large specific surface area (133.64 m2 g−1) of the current monolithic material gave rise to high binding capacities (11.54 mg g−1 for ovalbumin and 10.82 mg g−1 for horseradish peroxidase). The practicability of the resulting monolithic material was further evaluated by specific recognition and enrichment of glycoproteins from egg white and human serum samples, demonstrating its potential for separation and enrichment of glycoproteins from complex biological samples.
Co-reporter:Yukun Yang, Guozhen Fang, Xiaomin Wang, Mingfei Pan, Hailong Qian, Huilin Liu, Shuo Wang
Analytica Chimica Acta 2014 Volume 806() pp:136-143
Publication Date(Web):2 January 2014
DOI:10.1016/j.aca.2013.11.023
•PPY-GO-BiCoPc composite was formed using a simple electrochemical method for the first time.•A novel PoPD-MIP sensor based on PPY-GO-BiCoPc composite had been fabricated.•The PPY-GO-BiCoPc functional composite was introduced to improve performance of the sensor.•Highly sensitive, selective and stable sensor had been achieved.•The established MIP sensor could be promising in food safety analysis.A facile and efficient molecularly imprinted polymer (MIP) recognition element of electrochemical sensor was fabricated by directly electro-polymerizing monomer o-phenylenediamine (oPD) in the presence of template quinoxaline-2-carboxylic acid (QCA), based on one-step controllable electrochemical modification of poly(pyrrole)-graphene oxide-binuclear phthalocyanine cobalt (II) sulphonate (PPY-GO-BiCoPc) functional composite on glassy carbon electrode (GCE). The MIP film coated on PPY-GO-BiCoPc functional composite decorated GCE (MIP/PPY-GO-BiCoPc/GCE) was presented for the first time. The synergistic effect and electro-catalytic activity toward QCA redox of PPY-GO-BiCoPc functional composite were discussed using various contrast tests. Also, the effect of experimental variables on the current response such as, electro-polymerization cycles, template/monomer ratio, elution condition for template removal, pH of the supporting electrolyte and accumulation time, were investigated in detail. Under the optimized conditions, the proposed MIP sensor possessed a fast rebinding dynamics and an excellent recognition capacity to QCA, while the anodic current response of square wave voltammetry (SWV) was well-proportional to the concentration of QCA in the range of 1.0 × 10−8–1.0 × 10−4 and 1.0 × 10−4–5.0 × 10−4 mol L−1 with a low detection limit of 2.1 nmol L−1. The established sensor was applied successfully to determine QCA in commercial pork and chicken muscle samples with acceptable recoveries (91.6–98.2%) and satisfactory precision (1.9–3.5% of SD), demonstrating a promising feature for applying the MIP sensor to the measurement of QCA in real samples.
Co-reporter:Shujun Wang, Jinrong Wang, Jinglin Yu, Shuo Wang
Food Chemistry 2014 Volume 164() pp:332-338
Publication Date(Web):1 December 2014
DOI:10.1016/j.foodchem.2014.05.055
•The annealing of maize starches differing in amylose content was studied.•Annealing resulted in slight change in starch structure and in vitro digestibility.•The functional properties of starch were altered significantly.•Annealing enhanced interaction of amylopectin clusters by amylose rearrangement.•The role of amylose during starch annealing depended on the annealing conditions.The effect of annealing on starch structure and functionality of three maize starches (waxy, normal and high-amylose) was investigated, with the aim of understanding the role of amylose molecules during starch annealing. Amylose content, granular morphology and crystallinity of maize starches were little affected by annealing treatment. Annealing treatment did not alter the swelling power of waxy maize starch, but reduced the swelling power of normal and high-amylose maize starches. The thermal transition temperatures were increased, and the temperature range was decreased, but the enthalpy change was not affected greatly. The pasting viscosities of normal and waxy maize starches were decreased significantly, with the pasting temperature being little affected. The in vitro digestibility of three maize starches was not affected significantly by annealing treatment. Our results demonstrated that amylose molecules play an important role in the structural reorganization of starch granules during annealing treatment.
Co-reporter:Bing Liu;Lulu Ou;Fuyuan Zhang;Zhijun Zhang;Hongying Li;Mengyu Zhu
Journal of Separation Science 2014 Volume 37( Issue 23) pp:3579-3586
Publication Date(Web):
DOI:10.1002/jssc.201400799
In the study, four different semiempirical algorithms, modified neglect of diatomic overlap, a reparameterization of Austin Model 1, complete neglect of differential overlap and typed neglect of differential overlap, have been applied for the energy optimization of template, monomer, and template-monomer complexes of imprinted polymers. For phosmet-, estrone-, and metolcarb-imprinted polymers, the binding energies of template-monomer complexes were calculated and the docking configures were assessed in different molar ratio of template/monomer. It was found that two algorithms were not suitable for calculating the binding energy in template-monomers complex system. For the other algorithms, the obtained optimum molar ratio of template and monomers were consistent with the experimental results. Therefore, two algorithms have been selected and applied for the preparation of enrofloxacin-imprinted polymers. Meanwhile using a different molar ratio of template and monomer, we prepared imprinted polymers and nonimprinted polymers, and evaluated the adsorption to template. It was verified that the experimental results were in good agreement with the modeling results. As a result, the semiempirical algorithm had certain feasibility in designing the preparation of imprinted polymers.
Co-reporter:Yan Zhang, Zhou Luo, Zeping Shao, Chundi Yu, and Shuo Wang
Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 20) pp:4798-4802
Publication Date(Web):May 7, 2014
DOI:10.1021/jf500483y
The inhibitory effects of antioxidants of bamboo leaves (AOB) and flavonoids against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation were investigated in creatinine and phenylalanine model systems. AOB and the tested flavonoids (orientin, homoorientin, vitexin, isovitex, apigenin, luteolin, isorhamnetin, fisetin, and hesperetin) had significant dose-dependent inhibition effects on PhIP formation with different IC50 values. The superoxide anion (O2•–) scavenging activities of these nine flavonoids were evaluated using the pyrogallol autoxidation system. The EC50 values of compounds that showed antioxidant activity were found to correlate well (R2 = 0.8003) with the corresponding IC50 values representing their inhibition of PhIP formation. It was assumed that the inhibitory effects of flavonoids on PhIP formation were probably achieved by scavenging free radicals generated in the reaction system. These findings provide valuable information for the development of effective strategies to minimize heterocyclic amine content in thermally processed food.
Co-reporter:Yang Lu, Yinqiang Xia, Mingfei Pan, Xiaojun Wang, and Shuo Wang
Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 51) pp:12471-12476
Publication Date(Web):December 4, 2014
DOI:10.1021/jf504055g
A sensitive and stable surface plasmon resonance (SPR) immunosensor based on the inhibition format was developed and validated for detecting melamine (MEL) in milk products and pet foods. The sensitivity and the limit of detection (LOD) of the proposed method for MEL were 2.32 × 10–2 and 1.4 × 10–3 μg/mL, respectively. The immunosensor was highly specific to MEL, which displayed only low cross-reactivity (CR) (<0.01%) for cyanuric acid, cyanuric chloride, and atrazine. The assay was validated for the detection of MEL in full-cream milk, skim milk powder, infant formula, dog food, and cat food. Most of the recovery results ranged between 76 and 115%. The sensitivities of the assay in each type of sample were 2.57 × 10–2 μg/mL, 2.32 × 10–2 μg/kg, 2.51 × 10–2 μg/kg, 2.66 × 10–2 μg/kg, and 2.68 × 10–2 μg/kg, respectively, which were much lower than the maximum residue levels (MRLs) of MEL.
Co-reporter:Guozhen Fang, Chao Fan, Huilin Liu, Mingfei Pan, Huidan Zhu and Shuo Wang
RSC Advances 2014 vol. 4(Issue 6) pp:2764-2771
Publication Date(Web):26 Nov 2013
DOI:10.1039/C3RA45172K
A novel molecularly imprinted optosensing material (MIOM) based on ionic liquid (IL)-stabilized CdSe/ZnS quantum dots (QDs) was prepared, for highly selective and sensitive recognition of the mycotoxin zearalenone (ZON). ZON is expensive and highly toxic, so the ZON analog cyclodo-decanyl-2,4-dihydroxybenzoate (CDHB) was instead used as the template. MIOM was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and adsorption experiment. Under optimal conditions, the relative fluorescence intensity of MIOM decreased linearly with increasing ZON concentration, in the range of 0.003–3.12 μmol L−1. MIOM had a detection limit of 0.002 μmol L−1. MIOM was used to detect ZON in corn, rice and wheat flours, and at three concentration levels 50, 100 and 500 ng g−1, ZON recoveries for these three cereals were 94.2–98.7%, 93.1–107.6% and 84.4–106.0%, respectively.
Co-reporter:Yanhong Liu, Rui Ma, Qiliang Deng, Lingling Zhang, Cuicui Liu and Shuo Wang
RSC Advances 2014 vol. 4(Issue 94) pp:52147-52154
Publication Date(Web):07 Oct 2014
DOI:10.1039/C4RA05713A
In this paper, two polymer materials were synthesized by using 1-allyl-3-butylimidazolium chloride ([ABIM][Cl]) or 1-vinyl-3-octylimidazolium bromide ([VOIM][Br]) as functional monomers, and arcylamide (AAm) as a co-functional monomer. Bovine serum albumin (BSA), bovine hemoglobin (BHb), lysozyme (Lyz), and cytochrome C (Cyt C) that have different properties were selected as model proteins to investigate the absorption and separation abilities of ionic liquids polymer materials. The selective absorption properties of two polymer materials for proteins were compared for the first time. The results showed that [ABIM][Cl] ionic liquid polymer material had a high binding capacity for BHb (828.5 mg g−1), and [VOIM][Br] polymer material possessed a high binding capacity for BSA (804.7 mg g−1). Different proteins can be separated by altering the cations of the ionic liquid. In addition, the structure, morphology and thermal properties of ILs polymer materials were characterized by scanning electron microscope (SEM), fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). These results indicated that the IL polymer materials created a tendency for the partition of proteins efficiently and may be applied in medical diagnosis, proteomics, biotechnology and sensors broadly.
Co-reporter:Jie Dai, Yan Zhang, Mingfei Pan, Lingjie Kong, and Shuo Wang
Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 23) pp:5269-5274
Publication Date(Web):May 13, 2014
DOI:10.1021/jf501092u
To rapidly detect histamine (HA) in foods, a novel material for HA-specific recognition was synthesized by a sol–gel process and coated on a quartz crystal microbalance (QCM) sensor. The Scatchard model was used to evaluate the adsorption performance of the material; high affinity for HA was demonstrated. Based on QCM frequency change, the sensor exhibited linear behavior for HA concentrations of 0.11 × 10–2 to 4.45 × 10–2 mg L–1, a detection limit of 7.49 × 10–4 mg kg–1 (S/N = 3), high selectivity for HA (selectivity coefficient >4) compared with structural analogues, good reproducibility, and long-term stability. The sensor was used to determine the concentration of HA in spiked fish products; the recovery values were satisfactory (93.2–100.4%) and compared well with those obtained by high-performance liquid chromatography (correlation coefficient, r2 = 0.9965).
Co-reporter:Shujun Wang, Heyang Luo, Jian Zhang, Yan Zhang, Zhonghu He, and Shuo Wang
Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 16) pp:3636-3643
Publication Date(Web):March 26, 2014
DOI:10.1021/jf500249w
The bread wheat starch was treated with 0.025 and 0.0625 M NaOH solution for 1, 2, and 3 weeks at 30 °C, and the changes in functionality and in vitro digestibility were evaluated. NaOH treatment reduced protein and lipid contents of wheat starch from 0.46 to 0.20% and from 0.59 to 0.25%, respectively. No significant changes were observed in the amylose content, relative crystallinity, and short-range order of double helices, but there was evidence showing that morphology of some starch granules was altered. The swelling power and starch solubility of wheat starch increased from 11.4 to 14.1 g/g and from 10.9 to 22.1%, respectively. The thermal transition temperatures were increased greatly, but the enthalpy change remained largely unchanged. Alkali treatment greatly decreased the pasting temperature, but the pasting viscosities were altered in different ways. The resistant starch (RS) content of wheat starch was decreased significantly from 69.9 to 45.2%, while the starch that is digested slowly (SDS) content was increased greatly from 13.6 to 34.5%. Our results showed that alkali treatment can significantly alter the functionality and in vitro digestibility of wheat starch granules by removing the surface proteins and lipids rather than significantly altering the internal structure of starch granules.
Co-reporter:Guozhen Fang, Hailong Qian, Qiliang Deng, Xuqin Ran, Yukun Yang, Cuicui Liu and Shuo Wang
RSC Advances 2014 vol. 4(Issue 30) pp:15518-15525
Publication Date(Web):17 Mar 2014
DOI:10.1039/C4RA00997E
A novel C18 reversed phase (RP) organic–silica hybrid cationic monolithic capillary column with an ionic liquid (IL) as organic monomer has been fabricated by a “one-pot” approach for capillary electrochromatography (CEC). Through copolymerization, the IL, 1-vinyl-3-octadecylimidazolium bromide (VC18HIm+Br−), was successfully anchored into the monolithic matrix which was formed through polycondensation of tetraethyl orthosilicate (TEOS) and triethoxyvinylsilane (VTES). Several experimental variables, which were essential to the preparation of the columns, such as the TEOS/VTES ratio, the content of H2O and the supermolecule template, the amount of IL and the polycondensation temperature were studied in detail, and three control columns were prepared to compare with this prepared novel hybrid monolithic column. Separation of various neutral, charged and basic analytes as well as protein samples on the VC18HIm+Br− hybrid monolithic column and control columns was achieved by CEC. It was found that the prepared hybrid monolithic column possessed its own superiority in separation. Besides, the retention mechanism of neutral analytes on this column was a typical reversed phase chromatographic retention mechanism, and the separation of charged compounds depended on the combination of electrophoretic mobility, ionic exchange interaction and hydrophobic interaction. Moreover, the prepared hybrid monolithic column also settled the problem of peak tailing for separating the basic analytes, and the separation of egg white demonstrated its potential in proteome analysis.
Co-reporter:Huilin Liu, Guozhen Fang, Shuo Wang
Biosensors and Bioelectronics 2014 Volume 55() pp:127-132
Publication Date(Web):15 May 2014
DOI:10.1016/j.bios.2013.11.064
•A novel molecularly imprinted optosensing material based on hydrophobic CdSe quantum dots (QDs) was synthesized.•Hydrophobic CdSe QDs were first introduced to the hydrophilic analyte imprinted polymer.•A one-pot room-temperature reverse microemulsion polymerization was used to synthesize the molecularly imprinted optosensing material.•The molecularly imprinted polymer based on hydrophobic CdSe QDs applied as a molecular recognition element to construct ractopamine optosensor.A novel molecularly imprinted polymer (MIP) based on hydrophobic CdSe quantum dots (QDs) was synthesized using a one-pot room-temperature reverse microemulsion polymerization, and this polymer was applied as a molecular recognition element to construct a ractopamine (RAC) optosensor. Here, hydrophobic CdSe QDs were first introduced to the hydrophilic analyte-imprinted polymer for highly selective and sensitive detection of RAC via the change in fluorescence intensity, because of the high-quality hydrophobic QDs with high quantum yield, sharp photoluminescence spectra and chemical and fluorescent stability. Under optimal conditions, the relative fluorescence intensity of MIP based on hydrophobic QDs decreased linearly with the increasing concentration of RAC in the range of 1.21×10−9–3.03×10−6 mol L−1 with a detection limit of 7.57×10−10 mol L−1, and the precision for five replicate detections of 1.51×10−8 mol L−1 RAC was 2.09% (relative standard deviation). The proposed method was successfully applied for the determination of trace RAC in pork samples, with good recoveries ranging from 82.79% to 97.23%.
Co-reporter:Shifang Yuan, Qiliang Deng, Guozhen Fang, Jianhua Wu, Wangwang Li, Shuo Wang
Journal of Chromatography B 2014 960() pp: 239-246
Publication Date(Web):
DOI:10.1016/j.jchromb.2014.04.021
Co-reporter:Huilin Liu;Guozhen Fang;Huidan Zhu
Food Analytical Methods 2014 Volume 7( Issue 7) pp:1443-1450
Publication Date(Web):2014 August
DOI:10.1007/s12161-013-9768-4
Acting as a fluorescence sensing material, the molecularly imprinted polymer (MIP) appended onto quantum dots (QDs) was constructed through anchoring the MIP layer on CdSe/ZnS QDs by simple embedding for highly selective and sensitive optosensing of tocopherol (TP) in rice. The resulting composite of QDs with MIP showed higher template selectivity versus that of non-imprinted polymer (NIP). Under optimal conditions, the relative fluorescence intensity of MIP appended onto QDs decreased linearly (r2 > 0.99) with the increasing TP in the concentration in the range of 1.16 × 10−7–1.74 × 10−3 mol L−1 with a detection limit of 5.80 × 10−8 mol L−1, and the precision for five replicate detections of 1.0 × 10−4 mol L−1 TP was 2.17 % (relative standard deviation). Recoveries of 90.40 to 100.20 % were achieved by direct detection when MIP appended onto QDs was used for the selective separation of TP in rice samples.
Co-reporter:Yan Zhang;Chao Tan;Jieqiong Zhang;Wei Sheng
Food Analytical Methods 2014 Volume 7( Issue 6) pp:1305-1311
Publication Date(Web):2014 July
DOI:10.1007/s12161-013-9750-1
The mung bean allergen has not yet attracted attention on a global scale for the potential hazards it poses to allergen-sensitive individuals. In the current study, a sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of trace amounts of mung bean proteins was established. Mung bean protein-specific antibodies produced in rabbits and mice immunized with protein extracted from mung bean flour were used as the capture and detection antibodies in the ELISA. The ELISA had a limit of detection of 4.99 ng/mL and did not show any cross-reactivity with nine different foods, which potentially coexisted in foodstuffs. Accuracy and repeatability were validated by spiking and recovery of mung bean protein in oat meal, milk, and soybean milk. The suitability of the ELISA for the detection of mung bean protein in thermally processed samples was established by subjecting mung bean protein, mung bean powder, and defatted mung bean powder to dry or moist heating. The results demonstrated that the accurate quantitation of mung bean protein can be established for samples processed by dry heating at ≤150 °C. Lower detection results could not be avoided for mung bean proteins subjected to either dry heating at temperatures >150 °C or with moist heat, most probably because of changes in protein solubility and structure of the mung bean protein.
Co-reporter:Guozhen Fang;Jingjing Feng;Yifan Yan;Cuicui Liu
Food Analytical Methods 2014 Volume 7( Issue 2) pp:345-351
Publication Date(Web):2014 February
DOI:10.1007/s12161-013-9632-6
A highly selective determination method for chrysoidine, an industrial azoic dye banned in foods, was developed through a novel molecularly imprinted polymer (MIP) online solid-phase extraction coupled with high-performance liquid chromatography. The MIP was firstly synthesized by a surface molecular imprinting technique in combination with a sol–gel process and characterized by FT-IR and adsorption experiments. The MIP exhibited high selectivity and high adsorption capacity for chrysoidine and offered a fast kinetics for the adsorption and desorption of chrysoidine. A number of parameters, including the pH of loading solution, the sample loading flow rates, and eluting time of analyte, were carefully optimized to improve the extraction efficiency. Under the optimal experimental conditions, for a 50-mL sample solution, the enrichment factor was 279 and the detection limit (S/N = 3) was 6 ng L−1. The linear plots with r2 > 0.99 were achieved over a range of 0.04–40 μg L−1, and the peak area precision (relative standard deviation) for nine parallel determinations was below 6.32 %. This method was employed for quantitative determination of chrysoidine in oil bean curd, yellow croaker, and paprika with satisfactory recoveries (89.3–97.6 %).
Co-reporter:Ling-Jie Kong, Ming-Fei Pan, Guo-Zhen Fang, Xin-lei He, Yu-kun Yang, Jie Dai, Shuo Wang
Biosensors and Bioelectronics 2014 Volume 51() pp:286-292
Publication Date(Web):15 January 2014
DOI:10.1016/j.bios.2013.07.043
•This research combined the advantages of nanoparticle synergy, molecular imprinting technology and piezoelectric sensing.•The integration of Au nanoparticles into the electrodeposited membrane has enhanced the sensor's sensitivity for ractopamine analysis.•This work provides a promising method for enhancing the performance of MIP-based chem- and bio-sensors.A molecularly imprinted quartz crystal microbalance (QCM) sensor for ractopamine (RAC) detection was developed by electrodepositing a poly-o-aminothiophenol membrane on an Au electrode surface modified by self-assembled Au nanoparticles (AuNPs). The modified electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. This molecularly imprinted QCM sensor showed good frequency response in RAC binding measurements and the introduction of AuNPs demonstrated performance improvements. Frequency shifts were found to be proportional to concentration of RAC in the range of 2.5×10−6 to 1.5×10−4 mol L−1 with a detection limit of 1.17×10−6 mol L−1 (S/N=3). The sensor showed a good selective affinity for RAC (selectivity coefficient >3) compared with similar molecules and good reproducibility and long-term stability. This research has combined the advantages of high specific surface area of AuNPs, high selectivity from molecularly imprinted electrodeposited membrane and high sensitivity from quartz crystal microgravimetry. In addition, the modified electrode sensor was successfully applied to determine RAC residues in spiked swine feed samples with satisfactory recoveries ranging from 87.7 to 95.2%.
Co-reporter:Huilin Liu, Dongrui Liu, Guozhen Fang, Fangfang Liu, Cuicui Liu, Yukun Yang, Shuo Wang
Analytica Chimica Acta 2013 Volume 762() pp:76-82
Publication Date(Web):31 January 2013
DOI:10.1016/j.aca.2012.11.047
A novel dual-function material was synthesized by anchoring a molecularly imprinted polymer (MIP) layer on CdTe/ZnS quantum dots (QDs) using a sol–gel with surface imprinting. The material exhibited highly selective and sensitive determination of ractopamine (RAC) through spectrofluorometry and solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). A series of adsorption experiments revealed that the material showed high selectivity, good adsorption capacity and a fast mass transfer rate. Fluorescence from the MIP-coated QDs was more strongly quenched by RAC than that of the non-imprinted polymer, which indicated that the MIP-coated QDs acted as a fluorescence sensing material could recognize RAC. In addition, the MIP-coated QDs as a sorbent was also shown to be promising for SPE coupled with HPLC for the determination of trace RAC in feeding stuffs and pork samples. Under optimal conditions, the spectrofluorometry and SPE-HPLC methods using the MIP-coated QDs had linear ranges of 5.00 × 10−10–3.55 × 10−7 and 1.50 × 10−10–8.90 × 10−8 mol L−1, respectively, with limits of detection of 1.47 × 10−10 and 8.30 × 10−11 mol L−1, the relative standard deviations for six repeat experiments of RAC (2.90 × 10−9 mol L−1) were below 2.83% and 7.11%.Graphical abstractHighlights► We have developed a novel dual-function MIP-coated QDs material. ► The MIP-coated QDs combine the advantage of molecular imprinting and QDs. ► We used MIP-coated QDs as fluorescence sensing material for recognize RAC. ► We used QDs@MIP as sorbent to combine SPE with HPLC for the determination.
Co-reporter:Guozhen Fang, Yu Wu, Xiaomeng Dong, Cuicui Liu, Shaoyuan He, and Shuo Wang
Journal of Agricultural and Food Chemistry 2013 Volume 61(Issue 16) pp:3834-3841
Publication Date(Web):April 8, 2013
DOI:10.1021/jf400619y
Simultaneous detection of two classes of dyes possessing different chemical properties is difficult. In this study, through negative/positive ion switching mode, simultaneous determination of four typical acid orange dyes and three typical basic orange dyes was achieved by a single high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) method, and the analytical efficiency of multiresidues identification was greatly improved. To enhance detection sensitivity, the sample pretreatment conditions and HPLC-MS/MS determining conditions were carefully optimized. Under optimal conditions, good linearity was obtained over the range of 5–500 μg L–1 with a correlation coefficient (R2) >0.9998. Limits of detection (LODs) and limits of quantification (LOQs) of the seven dyes were 0.5–3.0 and 2.0–6.0 μg kg–1, respectively. The recoveries of the seven dyes in soybean products and marinated eggs were 74–126% with relative standard deviations (RSDs) of 2.22–25.4%, suggesting the developed method is promising for the accurate quantification of the seven dyes at trace levels in foods.
Co-reporter:Changmo Li, Yubin Zhang, Shuai Li, Guanhua Wang, Chong Xu, Yingying Deng, and Shuo Wang
Journal of Agricultural and Food Chemistry 2013 Volume 61(Issue 43) pp:10392-10397
Publication Date(Web):September 13, 2013
DOI:10.1021/jf402854b
To elucidate the relationship between heat-induced cis/trans isomerization and reaction temperature and energy in unsaturated lipids, we investigated the molecular mechanism of the heat-induced cis/trans isomerization of 18:1 isomers. Triolein (18:1,9c) was heated at two range temperatures (130, 160, 190, 220 °C and 135, 140, 145, 150, 155 °C) and analyzed by the gas chromatography (GC) method. When the heating temperature increased to 150 °C, the amount of trans 18:1n-9 changed from 0.0897 mg/g oil (1 h) to 0.1700 mg/g oil (3 h). This study shows that the cis to trans isomerization may occur at 150 °C. The formation of fatty acid isomers followed a proton transfer route. All key geometries, transition states, intermediates, and bond dissociation energies (BDE) were optimized at the B3LYP/6-31G* level for the density functional theory (DFT). The zero-point energy corrections of the isomers were carried out using calculations at the B3LYP/6-311++G** level. The calculated energy difference between the cis and trans oleic acid was equal to 7.6 kJ/mol, and the energy barriers of the transition from cis 18:1n-9 to trans 18:1n-9 were 294.5 kJ/mol. The intrinsic reaction coordinates (IRCs) were obtained to be used as an expression of the reaction route and to analyze the transition states and intermediates. The study results suggest that the heating temperature should be kept under 150 °C, to avoid the risk of trans fatty acid (TFA) intake in daily food.
Co-reporter:Shaolong Feng, Fang Gao, Zhiwen Chen, Edward Grant, David D. Kitts, Shuo Wang, and Xiaonan Lu
Journal of Agricultural and Food Chemistry 2013 Volume 61(Issue 44) pp:10467-10475
Publication Date(Web):October 7, 2013
DOI:10.1021/jf4038858
We report the development of a novel hybrid “capture–detection” molecularly imprinted polymers–surface-enhanced Raman spectroscopic (MIPs-SERS) biosensor for the detection and quantification of α-tocopherol (α-Toc) in vegetable oils. α-Toc served as the template for MIPs synthesis. Methacrylic acid formed as the functional monomer. Ethylene glycol dimethacrylate was the cross-linking agent, and 2,2′-azobisisobutyronitrile was used as the initiator. The synthesized MIPs functioned to rapidly and selectively adsorb and separate α-Toc from oil components. We validated a dendritic silver nanostructure synthesized by a displacement reaction to be a suitable SERS substrate for the enhancement of Raman signals. Second-derivative transformations and chemometric models based upon SERS spectral features confirmed the possibility of a rapid and precise detection and quantification of different spiking levels of α-Toc in four different sources of vegetable oils (Mahalanobis distance from 15.93 to 34.01 for PCA model; R > 0.92, RMSE < 0.41 for PLSR model). The MIPs-SERS biosensor had a high sensitivity as well as a good recovery for α-Toc analysis in vegetable oils. The entire analysis required 15 min or less to complete with limited sample preparation.
Co-reporter:Kun Qian, Guozhen Fang and Shuo Wang
RSC Advances 2013 vol. 3(Issue 12) pp:3825-3828
Publication Date(Web):18 Jan 2013
DOI:10.1039/C3RA23003A
A novel core–shell molecularly imprinted polymer based on β-NaYF4: Yb3+, Er3+ upconversion fluorescent nanoparticles (UCNPs@MIP) has been successfully synthesized, which has a homogeneous polymer film, shows thermal stability, exhibits excellent near-infrared upconversion luminescence emission and sensitivity and selectivity towards analytes.
Co-reporter:Huilin Liu, Lei Ren, Guozhen Fang, Hongying Li and Shuo Wang
Analytical Methods 2013 vol. 5(Issue 20) pp:5677-5683
Publication Date(Web):12 Aug 2013
DOI:10.1039/C3AY40880A
This paper describes the development of a direct competitive enzyme-linked immunosorbent assay with a molecularly imprinted film as an artificial antibody to measure trace tribenuron-methyl (TBM) in environmental water and soil samples. The molecularly imprinted film was directly synthesized on the well surface of a MaxiSorp polystyrene 96-well plate by a non-covalent approach, and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and static and kinetic adsorption experiments. Under optimum conditions, the IC50 and IC15 of the established method are 19.73 μg L−1 and 0.30 μg L−1, respectively, and its cross-reactivity with three sulfonylurea herbicides is in the range of 3.17–13.10%. The method was successfully applied to the determination of TBM in spiked environmental water and soil samples with recoveries from 93.6 to 96.8% and 87.5 to 97.5%, respectively. The results are in good agreement with those obtained by high performance liquid chromatography.
Co-reporter:Bing Liu, Yu Ge, Yan Zhang, Yang Song, Yurun Chen and Shuo Wang
Analytical Methods 2013 vol. 5(Issue 21) pp:5938-5943
Publication Date(Web):20 Aug 2013
DOI:10.1039/C3AY40825F
A simple and sensitive enhanced chemiluminescence enzyme linked immunosorbent assay (ECL-ELISA) has been developed for the detection of phosmet (PMT), azinphos-methyl (APM) and azinphos-ethyl (APE) residues in vegetable samples. The concentration of the coating antibody and enzyme tracer as well as the effects of the pH value, ionic strength and organic solvent were studied. The measured sensitivities (IC50) of PMT, APM and APE were 8.56, 9.04 and 25.34 μg L−1, respectively. High throughput screening for PMT, APM, and APE residues was achieved with good accuracy by means of the ECL-ELISA. The measurement time of the ECL-ELISA method was 5–10% shorter than that of the traditional ELISA method, and the sensitivity of detection was 2–3.5 times lower than that of the traditional method.
Co-reporter:Xiaoyu Gao, Mingfei Pan, Guozhen Fang, Wei Jing, Shaoyuan He and Shuo Wang
Analytical Methods 2013 vol. 5(Issue 21) pp:6128-6134
Publication Date(Web):03 Sep 2013
DOI:10.1039/C3AY41083H
In this research, a novel dummy molecularly imprinted polymer (DMIP) was prepared through a sol–gel process using bisphenol A as the dummy template and the synthesized 1-(triethoxysilyl) propyl-3-aminopropyl imidazole bromide (SilprImN) as the functional monomer. The prepared SilprImN-DMIP was characterized by FT-IR and verified with a satisfied identification and penetration performance to bisphenol A in static and kinetic adsorption tests. Furthermore, this novel DMIP was applied as a solid-phase extraction (SPE) material to develop a method for the simultaneous determination of nine organochlorine pesticides (OCPs) in environmental and food samples coupled to a multi dimensional gas chromatograph-mass spectrometer system. The SPE parameters, including sample acidity (pH), sample loading rate, the eluent and elution volume, were optimized in detail to achieve a good extraction efficiency. In water, rice and tea leaf samples spiked with nine OCPs, the OCPs were simultaneously determined with suitable recoveries from 65.65% to 129.61% and a good relative standard deviation (n = 3) of 0.91%–11.47%, indicating the satisfied accuracy and precision of the developed method.
Co-reporter:Junping Wang, Huiying Zhang, Wei Sheng, Wei Liu, Lili Zheng, Xinzhe Zhang and Shuo Wang
Analytical Methods 2013 vol. 5(Issue 17) pp:4430-4435
Publication Date(Web):05 Jun 2013
DOI:10.1039/C3AY40131F
A highly reliable and accurate indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed for the detection of streptomycin (STR) in animal-derived foods. The half-maximum inhibition concentration (IC50) of the icELISA for STR was 2.00 ng mL−1 and the limit of detection (LOD, calculated as the IC15 value) was 0.24 ng mL−1. The cross-reactivities with other aminoglycoside antibiotics were very low except for dihydrostreptomycin (95.50%). The recoveries for all samples at five levels (15, 30, 120, 300, 600 ng g−1) ranged from 71.32% to 106.94%. The coefficients of variation of intra- and inter-assays were below 14%. There was a good correlation (R2 = 0.9854) between the data determined by this ELISA and the commercial kit. The analysis of variance of the recoveries showed the sufficiently high stability of the assay to STR in eight animal-derived foods (chicken, pork, chicken liver, pig liver, pig kidney, fish, shrimp, and cow milk). The ELISA allows for a rapid, low-cost, sensitive and accurate determination of STR residues in animal-derived foods.
Co-reporter:Yukun Yang, Guozhen Fang, Guiyang Liu, Mingfei Pan, Xiaomin Wang, Lingjie Kong, Xinlei He, Shuo Wang
Biosensors and Bioelectronics 2013 Volume 47() pp:475-481
Publication Date(Web):15 September 2013
DOI:10.1016/j.bios.2013.03.054
•A novel MIP sensor for quinoxaline-2-carboxylic acid detection was established.•MWNTs-CS functional layer was introduced to improve performance of the sensor.•Sol–gel technology was applied to form recognition element of the sensor.•In detail, performance of the sensor was discussed through various methods.•The established MIP sensor could be promising in food safety analysis.Quinoxaline-2-carboxylic acid (QCA) is difficult to measure since only trace levels are present in commercial meat products. In this study, a rapid, sensitive and selective molecularly imprinted electrochemical sensor for QCA determination was successfully constructed by combination of a novel modified glassy carbon electrode (GCE) and differential pulse voltammetry (DPV). The GCE was fabricated via stepwise modification of multi-walled carbon nanotubes (MWNTs)-chitosan (CS) functional composite and a sol–gel molecularly imprinted polymer (MIP) film on the surface. MWNTs-CS composite was used to enhance the electron transfer rate and expand electrode surface area, and consequently amplify QCA reduction electrochemical response. The imprinted mechanism and experimental parameters affecting the performance of MIP film were discussed in detail. The resulting MIP/sol–gel/MWNTs-CS/GCE was characterized using various electrochemical methods involving cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and DPV. The sensor using MIP/sol–gel/MWNTs-CS/GCE as working electrode showed a linear current response to the target QCA concentration in the wide range from 2.0×10−6 to 1.0×10−3 mol L−1 with a low detection limit of 4.4×10−7 mol L−1 (S/N=3). The established sensor with excellent reproductivity and stability was applied to evaluate commercial pork products. At five concentration levels, the recoveries and standard deviations were calculated as 93.5–98.6% and 1.7–3.3%, respectively, suggesting the proposed sensor is promising for the accurate quantification of QCA at trace levels in meat samples.
Co-reporter:Huilin Liu, Guozhen Fang, Huidan Zhu, Changmo Li, Cuicui Liu, Shuo Wang
Biosensors and Bioelectronics 2013 Volume 47() pp:127-132
Publication Date(Web):15 September 2013
DOI:10.1016/j.bios.2013.03.006
•We prepared molecularly imprinted polymer based on quantum dots and graphene oxide.•Graphene oxide was first introduced to the molecularly imprinted polymer.•The ionic liquid was used to improve fluorescence stability.•The prepared optosensing material was specific recognition of vitamin E.This work prepared a novel ionic liquid stabilized molecularly imprinted optosensing material based on quantum dots (QDs) and graphene oxide (GO) composites using a one-step polymerization for highly selective and sensitive specific recognition of vitamin E (VE). Here, GO was first introduced to the molecularly imprinted polymer (MIP) because of its ultra-high specific surface area which increases the rate of mass-transfer relative to that of traditional bulk MIP. The ionic liquid was used to provide the desired surface binding groups between the QDs and the GO, but also to improve their fluorescence stability by virtue of its high thermal and chemical stability. Under optimal conditions, the relative fluorescence intensity of MIP decreased linearly with the increasing concentration of VE in the range of 2.30×10−2–9.20×102 μM with a detection limit of 3.5 nM and the precision for five replicate detections of 92 μM VE was 1.67% (relative standard deviation). At three concentration levels, the recoveries for two samples achieved were 93.00–100.14% and 92.00–102.00%, respectively.
Co-reporter:Huilin Liu, Guozhen Fang, Changmo Li, Mingfei Pan, Cuicui Liu, Chao Fan and Shuo Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 37) pp:19882-19887
Publication Date(Web):08 Aug 2012
DOI:10.1039/C2JM33522K
A new molecularly imprinted polymer (MIP), which acts as a fluorescence nano-sensing material, has been developed for the highly selective and sensitive optosensing of tocopherol (TP). The material was constructed by anchoring the MIP layer on 1-vinyl-3-octylimidazolium ionic liquid (IL)-modified CdSe/ZnS quantum dots (QDs) by copolymerization. Here, the IL was first introduced to the surface of the QDs using a one-step modification of the electrostatic interactions to prepare uniform MIPs. The MIP fluorescence was more strongly quenched by TP than the non-imprinted polymer was, which indicated that the QDs@IL@MIP could recognize the corresponding TP without the need for inducers and derivatization.
Co-reporter:Shifang Yuan, Qiliang Deng, Guozhen Fang, Mingfei Pan, Xiaorui Zhai and Shuo Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 9) pp:3965-3972
Publication Date(Web):25 Jan 2012
DOI:10.1039/C2JM14577D
In this research, a new macroporous polymer material with an excellent adsorption capacity for proteins was synthesized in aqueous medium by using an ionic liquid polymeric monomer, 1-vinyl-3-butylimidazolium chloride (ViBuIm+Cl−). It is the first time an ionic liquid has been chosen as a functional monomer to prepare polymer material for protein adsorption. The prepared ionic liquid material exhibited strong binding ability for many kinds of proteins, especially for lysozyme with a maximum binding capacity of 755.1 mg g−1 under the optimum adsorption conditions. The ionic liquid monomer played an important role in the protein adsorption capacity of the material. In addition, the recognition property of the ionic liquid polymer material could be easily tuned by changing the anions of the ionic liquid. The morphology, structure, composition and thermal properties of the ionic liquid material were further characterized by scanning electron microscope (SEM), fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimeter (DSC) and thermogravimetric analyses (TGA). Easy preparation of the ionic liquid polymer material as well as high ability to adsorb proteins makes this material attractive and broadly applicable in biomacromolecular separation, biotechnology, assays and sensors.
Co-reporter:Qiliang Deng, Yanli Li, Jianhua Wu, Yang Liu, Guozhen Fang, Shuo Wang and Yukui Zhang
Chemical Communications 2012 vol. 48(Issue 24) pp:3009-3011
Publication Date(Web):17 Jan 2012
DOI:10.1039/C2CC17856G
Fluorescent conjugated polymer, poly(3-aminobenzoic acid), as a new class of fluorescence sensor for detection of trace amounts of water in organic solvents was developed. This sensor exhibits extraordinarily high sensitivity with a detection limit as low as 0.008 wt% for water in DMF.
Co-reporter:Meng Yuan, Wei Sheng, Yan Zhang, Junping Wang, Yijin Yang, Shuguang Zhang, Irina Yu. Goryacheva, Shuo Wang
Analytica Chimica Acta 2012 Volume 751() pp:128-134
Publication Date(Web):2 November 2012
DOI:10.1016/j.aca.2012.08.044
A gel-based non-instrumental immuno-affinity assay was developed for the rapid screening of chloramphenicol (CAP) in food samples with the limit of detection (LOD) of 1 μg L−1. The immuno-affinity test column (IATC) consisted of a test layer containing anti-CAP antibody coupled gel, and a control layer with anti-HRP antibody coupled gel. Based on the direct competitive immuno-reaction and the horseradish peroxidase enzymatic reaction, the test results could be evaluated visually. Basically, blue color development represented the negative results, while the absence of color development represented the positive results. In this study, CAP spiked samples of raw milk, pasteurized milk, UHT milk, skimmed milk powder, acacia honey, date honey, fish and shrimp were tested. Little or none sample pretreatment was required for this assay. The whole procedure was completed within 10 min. In conclusion, the gel-based immuno-affinity test is a simple, rapid, and promising on-site screening method for CAP residues in food samples, with no instrumental requirement.
Co-reporter:Yu Wang, Qi-Liang Deng, Guo-Zhen Fang, Ming-Fei Pan, Yang Yu, Shuo Wang
Analytica Chimica Acta 2012 Volume 712() pp:1-8
Publication Date(Web):27 January 2012
DOI:10.1016/j.aca.2011.10.023
A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm+Cl−) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0–12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ∼6.8 μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ∼147,000 plates m−1 for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC.Graphical abstractHighlights► ILs as functional monomer for capillary monolithic column. ► Separation of alkylbenzenes, thiourea analogues, and amino acids. ► The column generate a stable reversed EOF from pH 2.0 to 12.0. ► The column efficiency of 147,000 plates m−1 was obtained for thiourea.
Co-reporter:Meng Yuan, Yu Na, Lingling Li, Bing Liu, Wei Sheng, Xiaonan Lu, Ivan Kennedy, Angus Crossan, and Shuo Wang
Journal of Agricultural and Food Chemistry 2012 Volume 60(Issue 42) pp:10486-10493
Publication Date(Web):October 8, 2012
DOI:10.1021/jf303256r
Most immunoassays for determination of small molecules are still designed on the basis of the “trial and error” method, due to the lack of understanding of antibody recognition. In the present study, we developed a heterologous indirect competitive enzyme-linked immunosorbent assay for determination of triazine herbicides, with limits of detection for 11 triazines ranging from 0.05 to 29.4 μg/L. Mechanisms of the antigen–antibody interaction were studied by computer-aided molecular modeling (CAMM)-based quantitative structure–activity relationship analyses. Co-effects of the analytes’ substructural hydrophobic, electrostatic, and steric fields on antibody recognition were further revealed. Hydrophobicity of the antigens was demonstrated to have the most important impact. Even less exposed substituents provided hydrophobic force to the antigen–antibody interaction. Dislocated orientation of analyte functional groups could lead to steric hindrance and hydrophobic misleading of antibody recognition. This may happen even when the antigens contained the same substituent as the hapten. Frontier orbital energies also affect the reaction significantly. This study highlights of the power of CAMM-based analyses, providing insights into antibody recognition of small molecules.
Co-reporter:Ling-Jie Kong;Ming-Fei Pan;Guo-Zhen Fang
Analytical and Bioanalytical Chemistry 2012 Volume 404( Issue 6-7) pp:1653-1660
Publication Date(Web):2012 October
DOI:10.1007/s00216-012-6253-7
A simple electrochemical sensor based on a molecularly imprinted polymer film as the recognition element was developed for ractopamine (RAC) detection. This is the first report of a RAC-imprinted film on a gold electrode surface, synthesized through an electrochemical method using o-aminothiophenol as the functional monomer. The imprinting mechanism and experimental parameters affecting the capability of the imprinted film are discussed here. The sensor was successfully applied with constant potential amperometry for RAC detection in an indirect process with potassium ferricyanide as an electrochemical probe. The sensor had a rapid equilibrium time (120 s), high binding affinity and selectivity towards RAC, and with good reproducibility and stability. Under the experimental conditions applied, a linear relationship between the relative amperometric response and RAC ranged from 2.0 × 10−7 to 1.4 × 10−6 mol L−1, with a lower limit of detection (LOD) of 2.38 × 10−8 mol L−1 (signal to noise ratio = 3). The sensor was tested with feed samples spiked with trace amounts of RAC, with good recoveries between 87.4 and 90.5 %.
Co-reporter:Mingfei Pan, Guozhen Fang, Zhenjuan Duan, Lingjie Kong, Shuo Wang
Biosensors and Bioelectronics 2012 Volume 31(Issue 1) pp:11-16
Publication Date(Web):15 January 2012
DOI:10.1016/j.bios.2011.09.008
This study describes the development of a sensor with molecularly imprinted polymer (MIP) sensitized with MWCNTs and Salen-Co(III) as recognition element for methimazole (MMI) determination. This is the first report of MWCNTs and Salen-Co(III) in MIP being used to enhance its conductivity and catalytic activity in the electrochemical oxidation process. The electrocatalytic mechanism of MMI was explained in detail by evaluating the obtained voltammograms at various potential sweep rates and pH of buffer solutions. A stable, sensitive analytical method of differential pulse voltammetry (DPV) was developed using the prepared MWCNTs–Salen-Co(III)–MIP electrode for the determination of amounts of MMI, resulting in a linear range of 0.5–6.0 mg L−1 with detection limit of 0.048 mg L−1. It was also successfully applied for MMI determination in tablets and spiked urine sample. At three concentration levels, the recoveries for two samples were achieved to 94.0–100.1% and 87.8–101.8%, respectively. Analytical reproducibility and stability of the developed method were also evaluated by RSD, which were calculated as 4.6–6.6% and 2.0–6.1% (n = 3), respectively.Highlights► Electrochemical sensor with molecularly imprinted polymer as recognition element. ► MWCNTs and Salen-Co(III) was used to enhance the conductivity and catalytic activity of MIP. ► A stable, sensitive electro-analytical method was developed for methimazole determination.
Co-reporter:Guangqi Zheng;Changmo Li;Lili Guo
Journal of the American Oil Chemists' Society 2012 Volume 89( Issue 4) pp:561-566
Publication Date(Web):2012 April
DOI:10.1007/s11746-011-1956-z
The fatty acid (FA) analysis of microalgae Spirulina was studied by applying accelerated solvent extraction (ASE) and followed by purification using solid-phase extraction (SPE). The objective was to develop a sensitive and reliable purification procedure to remove pigment in lipids co-extracted from Spirulina. Four extraction solvents were used for the ASE lipids extraction. The extraction efficiency was ranked in the following order: chloroform:methanol > dichloromethane:methanol > ethanol > hexane. The major composition of fatty acids were examined. Hexane and chloroform:methanol were compared for the purification step. The amounts of sorbent (Silica gel H), sample, and the volume of eluent were optimized during SPE procedure. This purification step can successfully remove the pigments from extracted lipids. For 0.1 g algae sample, chloroform:methanol (2:1, v/v) was the optimal extraction solvent, 0.3 g silica gel was the optimal amount of sorbent, with 7 mL for the volume of eluent. For hexane as the extraction solvent, 0.5 g algae sample, 0.3 g silica gel was the optimal amount of sorbent, 5 mL was the optimal volume of eluent. The calibration curve was produced comprised from five samples that contained FAME concentrations which was ranged from 0.1 to 10 mg/L (R2 > 0.99). The recoveries of fatty acids were 67.97–134.37%, 74.20–99.13% and 98.34–115.42%, with standard deviations (SD) of three replicate detections ranged from 1.09 to 8.41%.
Co-reporter:Yan Zhang;Cuiping Lin;Guozhen Fang;Jingbo Mei
European Food Research and Technology 2012 Volume 234( Issue 2) pp:197-205
Publication Date(Web):2012 February
DOI:10.1007/s00217-011-1624-4
Carcinogenic heterocyclic aromatic amines are difficult to measure since only trace levels are present in processed meat products. In this study, typical heterocyclic aromatic amines, including 2-amino-3-methylimidazo [4,5-f] quinoline (IQ), 2-amino-3,4-dimethylimidazo [4,5-f] quinoline (MeIQ), 2-amino-3,8-dimethyli-midazo [4,5-f] quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimi-dazo [4,5-f] quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-ph-enylimidazo [4,5-b]pyridine (PhIP), were studied to develop a sensitive and accurate method for their rapid quantification in animal-derived products, with 2-Amino-3,4,7,8-dimethylimidazo [4,5-f] quinoxalline (TriMeIQx) as an internal standard. Liquid chromatography–electrospray-tandem mass spectrometry conditions were analyzed to enhance detection sensitivity. Diatomaceous earth was employed to extract heterocyclic aromatic amines from meat samples, and the analytes were purified and enriched using tandem solid phase extraction, with siliprep propylsulfonic acid coupled to a C18 cartridge. A number of parameters, including pH, eluent and volume, were carefully optimized to improve the extraction and purification efficiency. Under the optimal experimental conditions, the limits of detection for each analyte within the meat matrix were 0.5 pg (injected). The established method was applied to evaluate commercial meat products. At three spiked levels of 0.2, 1 and 4 μg kg−1, the recoveries and relative standard deviations were measured as 76.4–122.2 and 0.9–23.4%, respectively, suggesting the developed method is promising for the accurate quantification of heterocyclic aromatic amines at trace levels in processed meats.
Co-reporter:Kun Qian, Guozhen Fang and Shuo Wang
Chemical Communications 2011 vol. 47(Issue 36) pp:10118-10120
Publication Date(Web):08 Aug 2011
DOI:10.1039/C1CC12935J
A novel core–shell molecularly imprinted polymer is firstly prepared by coating the MIP shell onto the surface of the metal–organic framework, which shows a homogeneous polymer film, cubic shape, thermal stability, and exhibits a higher specific surface area and a faster transfer-mass speed compared with that of the bulk MIP.
Co-reporter:Meng Yuan, Bing Liu, Enmei Liu, Wei Sheng, Yan Zhang, Angus Crossan, Ivan Kennedy, and Shuo Wang
Analytical Chemistry 2011 Volume 83(Issue 12) pp:4767
Publication Date(Web):May 3, 2011
DOI:10.1021/ac200227v
An indirect competitive enzyme-linked immunosorbent assay (icELISA) for 12 phenylurea herbicides (PUHs) was established with the half-maximum inhibition concentration (IC50) of 1.7–920.7 μg L–1. A method of computer-aided molecular modeling was established in quantitative structure–activity relationship (QSAR) studies to obtain a deeper insight into the PUHs’ antibody interactions on how and which molecular properties of the analytes quantitatively affect the antibody recognition. A two-dimensional (2D)-QSAR model based on the Hansch equation and a hologram QSAR (HQSAR) model were constructed, and both showed highly predictive abilities with cross-validation q2 values of 0.820 and 0.752, respectively. It was revealed that the most important impact factor of the antibody recognition was the PUHs’ hydrophobicity (log P), which provided a quadratic correlation to the antibody recognition. Hapten–carrier linking groups were less exposed to antibodies during immunization; thus, groups of the analytes in the same position were generally considered to be less contributive to antibody recognition during immunoassay. But the results of substructure-level analysis showed that these groups played an important role in the antigen–antibody interaction. In addition, the frontier-orbital energy parameter ELUMO was also demonstrated as a related determinant for this reaction. In short, the result demonstrated that the hydrophobicity and the lowest unoccupied molecular orbital energy (ELUMO) of PUH molecules were mainly responsible for antibody recognition.
Co-reporter:Jinxing He, Guozhen Fang, Qiliang Deng, Shuo Wang
Analytica Chimica Acta 2011 Volume 692(1–2) pp:57-62
Publication Date(Web):29 April 2011
DOI:10.1016/j.aca.2011.02.056
Four isomers of ractopamine used as multi-template molecule, a molecularly imprinted capillary monolithic column was prepared by organic–inorganic hybrid method. The prepared imprinting capillary monolithic columns were characterized by SEM and FTIR, evaluated under capillary electrochromatograhy and the effect of electroosmotic flow and selectivity were studied in detail. It was found that the prepared imprinted monolithic column had good flow-through property when the ratio of methanol and toluene was 3:2. The result indicated that the imprinted monolithic column has good selectivity for four isomers of ractopamine, and under the conditions of pH value of buffer solution was 7 and 10% acetonitrile content in buffer, four isomers of ractopamine could be separated completely.
Co-reporter:Lu Guo, Qiliang Deng, Guozhen Fang, Wei Gao, Shuo Wang
Journal of Chromatography A 2011 Volume 1218(Issue 37) pp:6271-6277
Publication Date(Web):16 September 2011
DOI:10.1016/j.chroma.2011.07.016
In this report, vinylimidazolium ionic liquid as a functional monomer for preparation of chlorsulfuron (CS) imprinted polymers were first studied. The imprinted materials showed high selectivity for CS, and fast kinetics so that adsorption equilibrium was achieved within 5 min. These materials have been further employed to detect trace CS from water samples by online preconcentration coupled with HPLC. The sorbent offered good linearity (0.005–30 μg L−1, r2 > 0.99) for on-line solid-phase extraction of trace chlorsulfuron. Under the optimal experimental conditions, the recovery for chlorsulfuron was in the range of 81.0–110.1% for the water samples, with RSDs ranging from 1.2 to 7.6%.
Co-reporter:Changmo Li, Yunping Yao, Guozhong Zhao, Wen Cheng, Huilin Liu, Chunyang Liu, Zhen Shi, Yao Chen, and Shuo Wang
Journal of Agricultural and Food Chemistry 2011 Volume 59(Issue 23) pp:12493-12498
Publication Date(Web):November 4, 2011
DOI:10.1021/jf203760k
The similarities and differences of eight vegetable oils produced in China were investigated in terms of their fatty acid, sterol, and tocopherol compositions and subsequent data processing by hierarchical clustering analysis and principal component analysis. The lipid profiles, acquired by analytical techniques tailored to each lipid class, revealed great similarities among the fatty acid profiles of corn and sesame oil as well as few differences in their sterol profiles. It turns out that not only was there great similarity between the fatty acid profiles of corn oil and sesame oil but also there were not too many differences for the sterol profiles. Sunflower and tea-seed oil showed similar sterol compositions, while the tea-seed oil tocopherol was very similar to palm oil. The results demonstrated that the use of only one of these profiles was unreliable for indentifying oil origin and authenticity. In contrast, the use of the sterol or tocopherol profile together with the fatty acid profile more accurately discriminates these oils.
Co-reporter:Junping Wang, Guichun Yu, Wei Sheng, Man Shi, Baixue Guo, and Shuo Wang
Journal of Agricultural and Food Chemistry 2011 Volume 59(Issue 7) pp:2997-3003
Publication Date(Web):March 7, 2011
DOI:10.1021/jf104914d
A sensitive and broad class selective direct competitive enzyme-linked immunosorbent assay (ELISA) using monoclonal antibody (McAb) has been described for the detection of pyrethroids with phenoxybenzene group. One monoclonal antibody, 2G2E7, was obtained and characterized after fusion of myeloma cells with spleen cells isolated from BALB/c mice. The assay with the most selectivity for the family pyrethroids with phenoxybenzene group was optimized. The IC50 values of the optimized immunoassay were 1.8 μg L−1 for deltamethrin, 1.5 μg L−1 for cypermethrin, 2.0 μg L−1 for fluvalinate and fenvalerate, 2.2 μg L−1 for phenothrin, 2.4 μg L−1 for flucythrinate, 3.0 μg L−1 for fenpropathrin, and 5.0 μg L−1 for permethrin. River water samples fortified with pyrethroids were analyzed with the ELISA to evaluate the accurancy of the assay. The recoveries of pyrethroids in spiked water samples ranged from 74 to 108%. The results indicate that the ELISA developed can accurately simultaneously determine pyrethroids with phenoxybenzene group in water samples.
Co-reporter:Zhenjuan Duan, Guozhen Fang, Mingfei Pan, Jianghua Yi, Lipeng Fan, Wei Liu and Shuo Wang
Analytical Methods 2011 vol. 3(Issue 8) pp:1821-1827
Publication Date(Web):04 Jul 2011
DOI:10.1039/C1AY05011G
Veterinary antibiotics are environmental contaminants of recent concern, so this study was designed to develop an analytical method of simultaneous determination for quinoxaline-1,4-dioxides (QdNOs) and their metabolites in the aqueous environment at trace levels. The new method is based on on-line solid phase extraction (SPE) using cigarette filter (CGFR) as the sorbent coupled to high-performance liquid chromatography (HPLC). Five QdNOs (carbadox, olaquindox, cyadox, mequindox, quinocetone) and two major metabolites (quinoxaline-2-carboxylic acid and methyl-3-quinoxaline-2-carboxylic acid) were detected in the surface water. The cleaned CGFR precolumn selectively retained target analytes when untreated water samples were upload by a flow-inject pump. Then the enriched extracts were subsequently eluted by HPLC mobile phase to the analytical column for chromatographic analysis. The on-line setup was uncomplicated and automated. The on-line SPE conditions were optimized in detail including sample pH, sample loading flow rate, sample volume, eluent, elution time and sorbents. Under the optimal experimental conditions, the enrichment factors were 33.3–630.0 by preconcentrating 25.0 mL of water samples. Limits of detection (S/N = 3) ranged from 1.6 to 24.3 ng L−1. Satisfactory recoveries were obtained and ranged from 87.1 to 107.5% at two spiked levels in real water samples with high precision (RSD, 1.3–3.8%). The on-line SPE-HPLC method is simple, rapid, reliable, sensitive and could be applied for multiresidue determination of the QdNOs and their metabolites in water samples.
Co-reporter:Wei Sheng;Yuanzhen Li;Xin Xu;Meng Yuan
Microchimica Acta 2011 Volume 173( Issue 3-4) pp:307-316
Publication Date(Web):2011 June
DOI:10.1007/s00604-011-0560-0
We have developed a heterologous direct competitive enzyme-linked immunosorbent assay (ELISA) and a visual colloidal gold-based immunochromatographic assay (CGIA) for simultaneous determination of ofloxacin, marbofloxacin, and fleroxacin residues in milk using polyclonal antibodies. The half-maximum inhibition concentrations (IC50) of ofloxacin, marbofloxacin, fleroxacin, and limits of detection (LODs; calculated as IC15 values) are between 0.20 and 0.53 ng mL−1, and between 0.02 and 0.05 ng mL−1, respectively. The average recoveries range from of 78% to 113%, and the coefficients of variation of intra- and inter-assays are between 2 and 11%, and 3 to 19%, respectively. The LODs for ofloxacin, marbofloxacin, fleroxacin in milk are between 3.5 and 8.9 ng mL−1. The visual minimum detection limit of the optimized CGIA is 2 ng mL−1 for milk samples. The detection process can be completed within 10 min. The strips can be stored at 4 °C for 8 weeks without significant loss of activity. The results of the analysis of spiked samples showed that the CGIA can be applied to preliminary, fast, and on-site screening of milk samples. The ELISA and CGIA allow for a rapid, sensitive, and low-cost determination of (fluoro)quinolones residues in milk samples.
Co-reporter:Yi-Wei Tang;Guo-Zhen Fang;Jia-Le Li
Analytical and Bioanalytical Chemistry 2011 Volume 401( Issue 7) pp:
Publication Date(Web):2011 October
DOI:10.1007/s00216-011-5280-0
A novel molecularly imprinted polymer (MIP) for the separation and concentration of ractopamine (RAC) was prepared by a covalent imprinting approach and the template was removed successfully by hydrolysis, so that four carboxylic acid groups were left in the cavities and could specifically rebind RAC through noncovalent interaction: hydrogen bonding. The conditions for synthesis of the MIP were optimized during the polymerization process, and a molar ratio of template–functional monomer complexes to cross-linker of 1:3 was confirmed. The adsorption capacity of the MIP was 4.1-fold that of the nonimprinted polymer, and the adsorption reaction reached equilibrium after 25 min at 50 mg L-1 concentration. The results of the competitive adsorption test showed that the MIPs had specific recognition ability for the analyte RAC. In addition, the important factors affecting the efficiency of the method which was developed using the MIPs as a solid-phase sorbent for separation and determination of RAC combined with high-performance liquid chromatography with fluorescence detection were optimized. Under the optimum experimental conditions, the linear range of the calibration curve in the method was 0.05-5 μg L-1 (R2 = 0.98) and the limit of detection (signal-to-noise ratio of 3) was 0.01 μg L-1. The proposed method was applied to determination of RAC in spiked feedstuffs and urine samples, with recoveries ranging from 74.17 to 114.46% and relative standard deviation (n = 3) below 4.55 in all cases.
Co-reporter:Zhen-Juan Duan;Li-Peng Fan;Guo-Zhen Fang
Analytical and Bioanalytical Chemistry 2011 Volume 401( Issue 7) pp:
Publication Date(Web):2011 October
DOI:10.1007/s00216-011-5329-0
A new molecularly imprinted polymer (MIP), selective for major metabolites of quinoxaline-1,4-dioxides was firstly prepared by combining surface molecular imprinting technique with the sol–gel process. Methyl-3-quinoxaline-2-carboxylic acid (MQCA) was used as template, 3-aminopropyltriethoxysilane as functional monomer, and tetraethoxysilicane as cross-linker. The MIP was characterized by Fourier transform infrared and evaluated through static adsorption experiments. The results indicated that MIP had high adsorption capacity, fast binding kinetics for MQCA, and the polymer showed a high degree of cross-reactivity for quinoxaline-2-carboxylic acid (QCA). The MIP was then applied as a selective sorbent in an online solid phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC). For a 50-mL sample solution, enrichment factors of 1,349 and 1,046 for QCA and MQCA, respectively, and limits of detection (S/N = 3) of 0.8 and 2 ng L−1 for QCA and MQCA, respectively, were obtained (corresponding to 0.02 and 0.04 ng g−1 in solid samples for final 100 mL of sample solutions of 5 g of pork). The sample preparation protocol was simplified and only included one step extraction with acetonitrile (MeCN) after the release of target analytes through acidic hydrolysis without further sample cleanup. The new MIP-SPE-HPLC method was successfully applied to the quantification of trace QCA and MQCA in pork muscle with good recoveries ranging from 67% to 80% and RSD below 8%.
Co-reporter:Jingwei Sun, Tingting Dong, Yan Zhang, Shuo Wang
Analytica Chimica Acta 2010 Volume 666(1–2) pp:76-82
Publication Date(Web):7 May 2010
DOI:10.1016/j.aca.2010.03.051
A direct competitive enzyme linked immunosorbent assay in multi-enzyme tracers format for the simultaneous analysis of carbaryl and metolcarb in agricultural products is described in this study. The concentrations of coating antibodies and enzyme tracer were studied. Under the optimum conditions, the limits of detection of carbaryl and metolcarb were 0.15 μg L−1 and 1.2 μg L−1, respectively. Determination of carbaryl and metolcarb in fruit juices and vegetables was accomplished by simple, rapid and efficient extraction methods. Recoveries of spiked samples were great than 70%. Validation of the immunosorbent assay was conducted by comparison of results from high performance liquid chromatography (HPLC). The correlations between the data obtained using multi-enzyme tracers enzyme linked immunosorbent assay and high performance liquid chromatography were good. Results indicated that the new strategy for developing immunoassay for simultaneous quantitative determination of carbaryl and metolcarb residues was suitable in this study.
Co-reporter:Zhixiang Xu, Guozhen Fang, Shuo Wang
Food Chemistry 2010 Volume 119(Issue 2) pp:845-850
Publication Date(Web):15 March 2010
DOI:10.1016/j.foodchem.2009.08.047
In this paper, we prepared a highly selective imprinted polymer by a room temperature ionic liquid-mediated bulk polymerization technique, using dichlorvos as the template, methacrylic acid as the functional monomers, and trimethylolpropane trimethacrylate as the cross-linker. This functionalized material was characterized by FT-IR, static and kinetic adsorption experiments, and the results showed that this imprinted sorbent exhibited good recognition and selective ability, and offered fast kinetics for the adsorption and desorption of dichlorvos. Using the prepared material as a solid phase extraction sorbent, a novel sample pre-treatment technique that can be coupled to high-performance liquid chromatography (HPLC) had been developed for determination of trace dichlorvos residues in foods. Under the selected experimental condition, the detection limit (S/N = 3) of dichlorvos was 94.8 ng L−1, and the peak area precision (RSD) for five replicate detections of 10 μg L−1 dichlorvos was 4.41%. The blank samples of cucumber and lettuce spiked with dichlorvos at 0.005 and 0.02 μg g−1 levels were determined with recoveries ranging from 82.1% to 94.0%.
Co-reporter:Xu Zhixiang;Wang Shuo;Fang Guozhen;Song Jiajia;Zhang Yan
Chromatographia 2010 Volume 71( Issue 5-6) pp:397-403
Publication Date(Web):2010 March
DOI:10.1365/s10337-010-1472-6
We report a sensitive and simple method for analysis of traces of Sudan dyes in foods in which solid-phase extraction on activated silica gel for preconcentration was combined, on-line, with high-performance liquid chromatography. With a loading flow rate of 1.7 mL min−1 for sampling 50 mL Sudan I–IV at pH 6.7, enrichment factors ranging from 196 to 991 were achieved. Detection limits (S/N = 3) of Sudan I–IV were in the range 1.4–7.0 ng L−1, and the relative standard deviation for repeatability of peak areas in five replicate analyses of 0.01 μg L−1 Sudan I–IV was 2.2–4.5%. When blank food samples (chilli powder, chilli sauce, and duck eggs) were spiked with Sudan III at two levels (0.25 and 0.50 μg L−1) then analyzed by this method recovery ranged from 70.3 to 95.2%.
Co-reporter:Hongyan Zhang;Yan Zhang;Liguo Zang
Applied Biochemistry and Biotechnology 2010 Volume 160( Issue 1) pp:
Publication Date(Web):2010 January
DOI:10.1007/s12010-009-8844-0
Co-reporter:Junping Wang;Suxin Duan;Yan Zhang
Microchimica Acta 2010 Volume 169( Issue 1-2) pp:137-144
Publication Date(Web):2010 April
DOI:10.1007/s00604-010-0318-0
A reliable enzyme-linked immunosorbent assay method was developed for the assay of T-2 toxin in cereals and feedstuff. A hapten of the T-2 toxin was synthesized, and a polyclonal antibody with high affinity and specificity was obtained after immunization of rabbits. Compared to the other ELISA methods, the assay is simple, rapid and affordable. The concentration of T-2 causing 15% inhibition is 0.01 ± 0.001 ng mL−1, which makes the method more sensitive than others. The cross-reactivity against other mycotoxins is low, except for the HT-2 toxin. Sample extraction was achieved within 3 min. The recoveries from samples including barley, wheat, corn, oat, rice and feedstuff were between 75% and 102%, and the detection limit for T-2 toxin was lower than 4 ng g−1. The method was validated by high-performance liquid chromatography with tandem mass spectrometry detection.
Co-reporter:Yu Ge, Yufeng Duan, Guozhen Fang, Yan Zhang, Shuo Wang
Carbohydrate Polymers 2009 Volume 77(Issue 2) pp:188-193
Publication Date(Web):10 June 2009
DOI:10.1016/j.carbpol.2008.12.020
The conditions for extracting and purifying polysaccharides from fruit calyx of Physalis alkekengi var. francheti were investigated, including hot water extraction, ultrasonic wave-assistant extraction and enzyme extraction methods. Four polysaccharide fractions (PAVF I, II-a and III) were separated from the extracts of fruit calyx of P. alkekengi var. francheti using a DEAE anion-exchange column and Sephadex G-200 column. Their chemical compositions were determined in this study. On the basis of hydroxyl radical assay (OH), superoxide radical assay, 1,1-dipheny-l-2-picrylhydrazyl (DPPH) assay, the antioxidant activities of crude polysaccharide from fruit calyx of P. alkekengi var. francheti (FCP), PAVF I, II-a, -b and III were investigated. Among these contents, PAVF I has higher scavenging effects on DPPH, OH and superoxide anion-scavenging activities.
Co-reporter:Shuo Wang;Li Liu;Guozhen Fang;Chao Zhang ;Jinxing He
Journal of Separation Science 2009 Volume 32( Issue 9) pp:1333-1339
Publication Date(Web):
DOI:10.1002/jssc.200800565
Abstract
In this study, a molecularly imprinted functionalized polymer for the selective separation of ractopamine (RAC) was prepared by combining a surface molecular imprinting technique with a sol–gel method process. The polymer was evaluated by static, kinetic adsorption, and selective experiments. Results indicated that the molecularly imprinted polymer had high adsorption capacity, selective ability, and fast mass transfer rate. The polymer was applied for the determination of trace RAC through online SPE-HPLC. With a sample loading flow rate of 2 mL/min, the enhancement factor of 516.26 and the LOD (S/N = 3) of 4.6 ng/L were achieved, respectively, and the linear range of the calibration curve was 0.04–18 μg/L with r2 >0.99. The RAC in pork was determined at three spiked levels (0.5, 1, and 2 ng/g) with recoveries ranging from 55.86 to 67.28%.
Co-reporter:Shuo Wang, Zhixiang Xu, Guozhen Fang, Yan Zhang, Bing Liu and Huaping Zhu
Journal of Agricultural and Food Chemistry 2009 Volume 57(Issue 11) pp:4528-4534
Publication Date(Web):May 18, 2009
DOI:10.1021/jf900505k
We developed a fast and new direct competitive biomimetic enzyme-linked immunosorbent assay (BELISA) method for the determination of estrone in environmental water based on a novel molecularly imprinted film of controlled thickness as an artificial antibody. The imprinted film was directly synthesized on the well surface of MaxiSorp polystyrene 96-well plate by a room temperature ionic liquid-mediated chemical oxidative polymerization in conjunction with molecular imprinting technology. This novel film was characterized, and results showed that it exhibited an antibody-like binding ability, rapid adsorption speed, high stability, and hydrophilicity, which was particularly advantageous and suitable for BELISA development. This BELISA method had a higher selectivity for estrone than for the structurally related compounds, and competitive binding studies demonstrated various degrees of cross-reactivity with five estrogenic compounds ranging from 30 to 47%. Eighty minutes of analysis time was reduced when compared to that of traditional ELISA, while the imprinted film was able to be reused for more than 50 times without loss of sensitivity. The IC50 (calculated as the concentration giving 50% inhibition of color development) and the detection limit values under optimized experimental conditions were 200 ± 40 μg L−1 and 8.0 ± 0.2 μg L−1, respectively. This developed method was applied to the determination of estrone in spiked environmental water samples with excellent recoveries ranging from 80 to 95%, and the results correlated well with that obtained using the high performance liquid chromatography method.
Co-reporter:Guozhen Fang, Guang Min, Jinxing He, Chao Zhang, Kun Qian and Shuo Wang
Journal of Agricultural and Food Chemistry 2009 Volume 57(Issue 8) pp:3040-3045
Publication Date(Web):March 27, 2009
DOI:10.1021/jf803913q
A matrix solid-phase dispersion extraction (MSPDE) method was developed to extract 31 pesticides from agriculture samples using multiwalled carbon nanotubes (MWCNTs) as adsorbent prior to gas chromatography−mass spectrometry (GC−MS) determination. The comparisons of MWCNTs with C18 and diatomite were studied in the MSPD procedure. The results showed that the extracts obtained by using MWCNTs were cleaner than those obtained by using C18 and diatomite. Using the developed method, recoveries ranged from 74.2 to 104.2% with relative standard deviations (RSD) ranging from 3.1 to 8.8% for the apple matrix, and 71.5−113.3% with RSD ranging from 3.2 to 9.7% for the potato matrix. The limits of detection (LODs), calculated as 3 times the background noise, ranged from 0.1 to 3.1 μg kg−1 for the apple matrix and 0.1 to 4.0 μg kg−1 for the potato matrix. The proposed MSPDE method was used to analyze real samples obtained in a local market, the results were approximation to those obtained using accelerated solvent extraction (ASE) method, and prometryn, isocarbophos and methidathion were detected at levels below the maximum residue limits (MRLs) allowed by the Chinese Government.
Co-reporter:Wang Junping;Pan Mingfei;Fang Guozhen;Wang Shuo
Microchimica Acta 2009 Volume 166( Issue 3-4) pp:295-302
Publication Date(Web):2009 September
DOI:10.1007/s00604-009-0205-8
A molecularly imprinted functionalized sol-gel has been prepared by using enrofloxacin (ENRO) as a template, 3-aminopropyltriethoxysilane as the functional monomer, tetraethoxysilicane as a cross-linker. This ENRO-imprinted polymer was evaluated by static, kinetic adsorption and selective experiments. The polymer displays good selectivity, and fast kinetics in terms of adsorption and desorption. The material was applied as a sorbent for on-line determination of trace ENRO by high performance liquid chromatography, with a focus on biological matrices. At a loading flow rate of 1.0 mL min-1 for sampling 50 mL, the enrichment factor and limit of detection (LOD; at S/N = 3) are 566 and 8 ng L-1, respectively. The peak area precision (the LOD for nine replicate detections of 0.1 µg L-1 ENRO) is 4.4%. ENRO in fish and chicken muscle was determined at three spiked levels with recoveries ranging from 70% to 82%.
Co-reporter:Hongyan Zhang;Yan Zhang;Liguo Zang
Applied Biochemistry and Biotechnology 2009 Volume 158( Issue 3) pp:642-652
Publication Date(Web):2009 September
DOI:10.1007/s12010-008-8378-x
Four different immunoassays based on the same generic polyclonal antibody were validated by high performance liquid chromatography, respectively. They also were compared with each other in terms of sensitivity, precision, and accuracy for the quantification or screening of sulfonamide residues in food samples. Correlation studies showed that there was a good correlation between the immunoassays and liquid chromatography data. The conventional plate assay has better precision and the plate-enhanced chemiluminescent assay has higher sensitivity. These two methods all could be used as quantification methods for large numbers of samples and complements of the conventional analytical methods in laboratory. The flow-through strip assay has higher sensitivity and the dip-stick strip assay was less affected by matrix effect. These two methods all could be used as valuable tools for the rapid on-site screening of sulfonamide residues in animal-derived food samples.
Co-reporter:Shuo Wang, Wei Huang, Guozhen Fang, Jinxing He, Yan Zhang
Analytica Chimica Acta 2008 Volume 606(Issue 2) pp:194-201
Publication Date(Web):14 January 2008
DOI:10.1016/j.aca.2007.11.030
A method based on on-line solid-phase extraction (SPE) coupling to high-performance liquid chromatography (HPLC) for the determination of estrogens has been developed. This method can continuously perform extraction of estrone, estradiol, estriol and diethylstilbestrol from aqueous samples without any other pretreatment, which can then be analyzed by HPLC with a UV detector at 230 nm. A pre-concentration column was adapted with methanol/water for chromatographic separation and two kinds of sorbents were involved, which are octadecyl-bonded silica and cigarette filter. The condition of pH of samples, sample loading flow rate and desorption time were all optimized, and the performances of both two sorbents were satisfactory. The on-line SPE system requires very low maintenance and just involved a switching-valve-filter system and a flow-inject pump, and the operation of the whole SPE-HPLC instrumentation is quite simple. The detection limits for pre-concentrating 50 mL of standard solution using cigarette filter as sorbent ranged from 0.98 to 78.1 ng L−1. The enhancement factors were in the range of 197–326. The recoveries of estrogens spiked in real water samples ranged from 85 to 112%. The precisions for nine replicate measurements of a standard mixture (5.0 μg L−1) were in the range of 1.0–3.4%.
Co-reporter:Liqin Jiang, Guozhen Fang, Yan Zhang, Guojie Cao and Shuo Wang
Journal of Agricultural and Food Chemistry 2008 Volume 56(Issue 24) pp:11571-11577
Publication Date(Web):November 24, 2008
DOI:10.1021/jf802567r
A micellar electrokinetic capillary chromatography (MEKC) method has been developed for simultaneous determination of 10 bioactive flavonoids: rutin, apigenin, luteolin, eriodictyol, kaempferol, chrysin, acacetin, flavanone, flavone, and fisetin. The effect of several parameters, such as UV detection wavelength, buffer pH, buffer concentration, sodium dodecyl sulfate (SDS) concentration, β-cyclodextrin (β-CD) concentration, separation voltage, and injection time on the separation of these flavonoids were systematically investigated. The 10 flavonoids were successfully separated within 18 min in 20 mM Na2B4O7−10 mM NaH2PO4 buffer (pH 9.7) containing 100 mM SDS and 16 mM β-CD at a separation voltage of 19 kV, with UV detection at 254 nm. Regression analysis revealed a good linear relationship between the peak area of each analyte and its concentration with detection limits (S/N = 3), ranging from 0.15 to 1.36 μg mL−1. This method could simultaneously quantify the 10 flavonoids and be used in the quality control of functional foods containing propolis and Ginkgo biloba.
Co-reporter:Can Zhang, Guangpeng Ma, Guozhen Fang, Yan Zhang and Shuo Wang
Journal of Agricultural and Food Chemistry 2008 Volume 56(Issue 19) pp:8832-8837
Publication Date(Web):September 10, 2008
DOI:10.1021/jf801645m
A capillary electrophoresis-based competitive immunoassay (CEIA) with a laser-induced fluorescence (LIF) detector for the determination of carbaryl was developed. The method was based on the competitive reactions between fluorescently labeled carbaryl tracer (Ag*) and free carbaryl (Ag) with a limited amount of anticarbaryl antibody (Ab), and the relative amounts of each were separated and determined by capillary electrophoresis (CE) with an LIF detector. Using CEIA, equilibrium was reached in 30 min, and the analytical results were obtained within a further 8 min. The linear range and the detection limit for carbaryl were 0.16−50 ng/mL and 0.05 ng/mL, respectively. The sensitivity of this CEIA with an LIF detector was almost 14 times greater than that of ELISA, which used the same immuno-reagents. The method was also applied to the analysis of carbaryl in rice with rapid and simple sample pretreatment. The method is thus proposed as a fast and sensitive assay for the detection of carbaryl.
Co-reporter:Jinxing He, Shuo Wang, Guozhen Fang, Huaping Zhu and Yan Zhang
Journal of Agricultural and Food Chemistry 2008 Volume 56(Issue 9) pp:2919-2925
Publication Date(Web):April 2, 2008
DOI:10.1021/jf703680q
A selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol–gel process for online solid-phase extraction−HPLC determination of three trace sulfonamides in pork and chicken muscle. The imprinted functionalized silica gel sorbent exhibited selectivity and fast kinetics for the adsorption and desorption of sulfonamides. With a sample loading flow rate of 4 mL min−1 for 12.5 min, enhancement factors and detection limits for three sulfonamides (S/N = 3) were achieved. The precision (RSD) for nine replicate online sorbent extractions of 5 µg L−1 sulfonamides was less than 4.5%. The sorbent also offered good linearity (r2 > 0.99) for online solid-phase extraction of trace levels of sulfonamides. The method was applied to the determination of sulfonamides in pork and chicken muscle samples. The prepared polymer sorbent shows promise for online solid-phase extraction for HPLC determination of trace levels of sulfonamides in pork and chicken samples.
Co-reporter:Shuo Wang;Zhixiang Xu;Guozhen Fang;Yan Zhang;Jinxing He
Journal of Separation Science 2008 Volume 31( Issue 6-7) pp:1181-1188
Publication Date(Web):
DOI:10.1002/jssc.200700575
Abstract
Estrone has been identified as an important potential endocrine-disrupting compound, so that sensitive and reliable analytical methods are required for its determination and the assurance of human health. Using estrone as the template, acrylamide as the functional monomer, and methacryloxypropyltrimethoxysilane as the cross-linker, an organic-inorganic hybrid material has been synthesized by the molecular imprinting technique combined with a non-hydrolytic so-gel process. The synthesized polymer was characterized by FT-IR and static adsorption experiments, and the results showed that it had good recognition and selective ability for estrone. A novel method for separation and determination of trace estrone in water samples was developed using molecularly imprinted solid phase extraction coupled with HPLC. Under the selected experimental condition, the detection limit (S/N = 3) was 9.3 ng/L, and the RSD for five replicate extractions of 10 μg/L estrone was less than 5.0%. This method was employed for quantitative determination of estrone in river, lake, and tap water with recoveries ranging from 83.38 to 98.12%.
Co-reporter:Shuo Wang, Xiaojun Cui, Guozhen Fang
Food Chemistry 2007 Volume 103(Issue 4) pp:1487-1493
Publication Date(Web):2007
DOI:10.1016/j.foodchem.2006.09.023
Simple, sensitive and rapid methods for the determination of formaldehyde and sulfur dioxide were developed. The formaldehyde determination is based on the reaction between formaldehyde and acetylacetone solution, producing yellow 3,5-diacetyl-l-1,4-dihydrolutidine. Sulfur dioxide was detected as the deoxidize of sulfurous acid by zinc in acidic medium, which produces sulfureted hydrogen that make lead acetate paper blackening due to lead sulfide formation. The detection limits were 0.8 μg mL−1 and 6.0 μg mL−1 for formaldehyde and sulfur dioxide, respectively. The linear range were 0.8–20.0 μg mL−1 for formaldehyde and 6.0–100.0 μg mL−1 for sulfur dioxide determination. The main advantages of the new analytical procedure are the low background level, high selectivity, and very little sample preparation for on-site analysis of formaldehyde and sulfur dioxide in food or Chinese herbal samples with reference color card for qualitative or semi-quantitative determination. The results from these methods correlated well with those obtained from the standard methods.
Co-reporter:Ying Quan, Yan Zhang, Shuo Wang, Nanju Lee, Ivan R. Kennedy
Analytica Chimica Acta 2006 Volume 580(Issue 1) pp:1-8
Publication Date(Web):27 October 2006
DOI:10.1016/j.aca.2006.07.063
An enzyme-linked immunosorbent assay (ELISA) based on polyclonal antibody with enhanced chemiluminescent (ECL) detection of fumonisin B1 (FB1) in food samples has been developed. Assay conditions, including concentrations of antibody and enzyme conjugate, competition time and so on, were optimized. The effects of pH and two different organic solvents were investigated. The optimized ECL-ELISA system allowed FB1 determination in a linear working range of 0.14–0.9 μg L−1 with IC50 value of 0.32 μg L−1 and a limit of detection of 0.09 μg L−1. The ECL-ELISA was about 10 times more sensitive and about 30% time less than that of colorimetric ELISA using the same antibody and HRP-conjugate. Good recoveries with spiked food samples were obtained, and the results correlated well with those obtained using conventional direct competition ELISA assay and HPLC method, which indicated that ECL-ELISA was capable of being applied for the specific detection and routine monitoring of FB1 in food samples.
Co-reporter:S. Wang, B. Xu, Y. Zhang, J.X. He
Meat Science (May 2009) Volume 82(Issue 1) pp:53-58
Publication Date(Web):1 May 2009
DOI:10.1016/j.meatsci.2008.12.003
A colorimetric competitive direct enzyme-linked immunosorbent assay (ELISA) method was developed using polyclonal antibody to determine neomycin residues in food of animal origin. No cross-reactivity of the antibody was observed with other aminoglycosides. The limit of detection of the method was 0.1 μg/kg. A simple and efficient sample extraction method was established with recoveries of neomycin ranged from 75% to 105%. The detection limits were 5 μg/kg(l) in pig muscle, chicken muscle, fish and milk, 10 μg/kg in kidney and 20 μg/kg in egg, respectively. Chemiluminescence assay was developed for detecting neomycin residues in pig muscle and chicken muscle. The limit of detection of the method was 0.015 μg/kg, and the detection limits were 1.5 μg/kg in pig muscle and 6 μg/kg in chicken muscle. The ELISA tests were validated by HPLC, and the results showed a good correlation (r2) which was greater than 0.9.
Co-reporter:Shujun Wang, Jinglin Yu, Quanwei Xin, Shuo Wang, Les Copeland
Food Control (March 2017) Volume 73(Part B) pp:230-236
Publication Date(Web):1 March 2017
DOI:10.1016/j.foodcont.2016.08.002
•Reducing sugar contents increased with increasing starch damage in flour.•Fermentation increased the content of reducing sugars in the dough.•Fermentation decreased asparagine content of the dough and acrylamide formation.•The content of acrylamide in bread increased with starch damage in flour.•Reducing damaged starch in flour is an option to mitigate acrylamide formation.The effects of starch damage and yeast fermentation on the formation of acrylamide in wheat bread were studied. Four wheat cultivars were milled separately by three laboratory mills to obtain wheat flours with damaged starch content ranging from 1.7 to 6.6%. Reducing sugar contents increased with increasing damaged starch content in flour. Yeast fermentation decreased greatly the content of asparagine by 40–60% in the dough, but increased substantially the content of reducing sugar. Compared with the unleavened bread, dough fermentation significantly decreased the content of acrylamide in leavened bread. The content of acrylamide in bread increased with increasing damaged starch content in wheat flours from the same cultivar. This study clearly showed that damaged starch content in wheat flour and dough fermentation are two major determinants of the formation of acrylamide in bread. The mitigation of acrylamide formation in bread can be achieved by reducing damaged starch in flour and by fermentation of the dough.
Co-reporter:Xin-jun Du, Fei Wang, Xiaonan Lu, Barbara A. Rasco, Shuo Wang
Research in Microbiology (July–August 2012) Volume 163(Issues 6–7) pp:448-456
Publication Date(Web):1 July 2012
DOI:10.1016/j.resmic.2012.06.002
Cronobacter sakazakii is a wide-spread opportunistic foodborne pathogen that can form biofilms on a number of different substances, creating food safety risk. However, there is little information about biofilm characteristics for this species. In this study, biofilm formation of 14 foodborne C. sakazakii strains was examined. Transposon mutants of the strain (IQCC10423), the isolate with the greatest biofilm activity, were prepared. A total of 12 mutants were developed with >40% reduction in biofilm formation ability. Eight of these mutants were successfully sequenced with genes putatively identified for: biofilm formation, fundamental cellular processes, phage tail complete protein and uncertain functional protein. The morphology of the biofilm showed that the wild type strain formed a thick biofilm and mutants formed less extracellular polymeric substances (EPSs). Raman spectroscopy was employed to confirm less biofilm formation by different bacterial mutants and demonstrate a similar chemical composition, but different contents of EPS. Wild type biofilms contained a high level of carotenoids, with the distribution of carotenoids mapped using confocal Raman imaging. We demonstrate that various selective functional genes are responsible for the forming ability of C. sakazakii biofilms, which may have the potential to cause risks to food safety.
Co-reporter:Xia Zhang, Xin-Jun Du, Chun Guan, Ping Li, Wen-Jie Zheng, Shuo Wang
Molecular and Cellular Probes (August 2015) Volume 29(Issue 4) pp:208-214
Publication Date(Web):1 August 2015
DOI:10.1016/j.mcp.2015.05.001
•A new isothermal cross-priming amplification method was developed to detect all V. cholerae.•The efficiency and accuracy of detection were improved by using nucleic acid detection strips.•The method exhibits higher sensitivity and convenience than LAMP method.•The sensitivity of the method is similar with real-time PCR in artificially contaminated samples detection.Vibrio cholerae is a water- and food-borne human pathogen, and V. cholerae serotypes O1 and O139 have attracted attention because of their severe pathogenesis. However, non-O1, non-O139 cholera vibrios (NCVs) were also recently recognized as having virulence properties. In this study, we developed a cross-priming amplification (CPA) method for the detection of all serotypes of V. cholerae. The specificity of the CPA method was tested using a panel of 60 different bacterial strains. All of the V. cholerae strains showed positive results, and 41 other types of bacteria gave negative results. The limit of detection of the CPA method was 79.28 fg of genomic DNA, 4.2 × 102 CFU/ml for bacteria in pure culture, and 5.6 CFU per 25 g of sample with pre-enrichment. This method showed a higher sensitivity than the loop-mediated isothermal amplification (LAMP) method did and was more convenient to perform. These results indicate that the CPA method can be used for the rapid preliminary screening of V. cholerae.
Co-reporter:Xin-jun Du, Xiang Zhang, Xiao-yi Wang, Yu-lan Su, Ping Li, Shuo Wang
Food Control (April 2017) Volume 74() pp:9-16
Publication Date(Web):1 April 2017
DOI:10.1016/j.foodcont.2016.11.024
•The prevalence characteristics of L. monocytogenes (2.3% positive) were analyzed.•MLST indicated broad genetic diversity, and the predominant subtypes varied.•The isolates showed enhanced resistance to several commonly used antibiotics.•Most virulence genes were highly prevalent in the isolates.The objective of this study was to investigate the prevalence and characteristics of Listeria monocytogenes isolated from Chinese food, including frozen dumplings, flavored raw meat, roasted meat, braised meat, and a cold vegetable dish with sauce. A total of 900 food samples were collected from supermarkets, open-air markets, and delicatessens in three large cities in the central area of China to examine the presence of L. monocytogenes; 21 (2.3%) of the samples were positive for this pathogen. Among the different samples, braised meat showed the highest L. monocytogenes detection rate (4.4%). Samples obtained from delicatessens showed a much higher L. monocytogenes contamination rate (8.3%) than those from open-air markets (6.7%) or supermarkets (0%). Multilocus sequence typing (MLST) analysis indicated that the 21 bacterial isolates belonged to 12 ST subgroups. ST5 was the largest and contained 7 isolates (33.3%); it was followed by ST474, ST121 and ST9 (each containing 2 isolates [10.5%]). Antibiotic susceptibility analysis showed that the 21 L. monocytogenes isolates were thoroughly resistant to cefoxitin but highly susceptible to doxycycline and ciprofloxacin. The presence of 10 virulence genes was evaluated by PCR, which showed that inlA, inlC, inlJ, prfA, hlyA, and plcB were present in all isolates and that inlB, actA, plcA and iap were present in 71.4–90.5% of the isolates. This study provides a useful reference for risk assessment and control of L. monocytogenes contamination in Chinese food and for the treatment of clinical listeriosis.
Co-reporter:Xiaojun Cui, Guozhen Fang, Liqin Jiang, Shuo Wang
Analytica Chimica Acta (8 May 2007) Volume 590(Issue 2) pp:
Publication Date(Web):8 May 2007
DOI:10.1016/j.aca.2007.03.042
A simple and sensitive kinetic-spectrophotometric method was developed for the determination of ultra trace amount of formaldehyde in food samples. The method was based on the oxidation of rhodamine B (RhB) by potassium bromate in sulfuric acid medium (formaldehyde as catalyst). The reaction was monitored by measuring the decrease in absorbance of the dye at 515 nm after 6 min. The developed method allowed the determination of formaldehyde in the range of 10–100 μg L−1 with good precision, accuracy and the detection limit was down to 2.90 μg L−1. The relative standard deviations for the determination of 10 and 60 μg L−1 of formaldehyde were 3.0% and 1.9% (n = 10), respectively. The method was found to be sensitive, selective and was applied to the determination of formaldehyde in foods with satisfactory results.
Co-reporter:Hongyan Zhang, Shuo Wang, Guozhen Fang
Journal of Immunological Methods (31 May 2011) Volume 368(Issues 1–2) pp:1-23
Publication Date(Web):31 May 2011
DOI:10.1016/j.jim.2011.02.011
The recent development and application of multi-analyte simultaneous analysis by enzyme-linked immunosorbent assays (ELISAs) of many kinds of organic compounds are reviewed herein. Multi-analyte ELISAs based on generic antibodies directly, or on specific antibodies by multi-antibody co-coating or multi-tracer co-marking are described in detail. Special attention was placed on the design and synthesis of a generic hapten, the manner of linking the hapten to a carrier protein, type and character of the antibody and format of the ELISAs. It is hoped that this comprehensive review can be considered as a useful reference for further investigation of multi-analyte simultaneous analysis by ELISAs.Research highlights► Development of multi-analyte simultaneous analysis by ELISA are reviewed. ► Multi-analyte ELISAs based on generic antibodies are described in detail. ► Special attention was placed on the design and synthesis of a generic hapten.
Co-reporter:Hongwei Zhang, Luyao Ma, Lina Ma, Marti Z. Hua, Shuo Wang, Xiaonan Lu
International Journal of Food Microbiology (21 February 2017) Volume 243() pp:64-69
Publication Date(Web):21 February 2017
DOI:10.1016/j.ijfoodmicro.2016.12.003
•The mecA gene was used as the specific maker for the identification of MRSA.•Lateral flow immunoassay (LFI) strip was applied to test the PCR products.•PCR-LFI assay exhibited good performance on both sensitivity and specificity.•MRSA were successfully detected from imported pork products using PCR-LFI.Methicillin-resistant Staphylococcus aureus (MRSA) is considered as one of the leading causes of food poisonings worldwide. Due to the high prevalence and extensive challenges in clinical treatment, a rapid and accurate detection method is required to differentiate MRSA from other S. aureus isolated from foods. Since the methicillin resistance of S. aureus is due to the acquisition of the mecA gene from staphylococcal chromosome cassette, the presence of the mecA gene is interpreted as a marker for the identification of MRSA. In this study, a low-cost lateral flow immunoassay (LFI) strip was used to detect the mecA amplicons subsequent to polymerase chain reaction (PCR). The specificity of this PCR-LFI assay was tested between MRSA and methicillin-susceptive S. aureus. Both the test line and control line were shown up on the LFI strip for MRSA, whereas only the control line developed for methicillin-susceptive S. aureus. The detection limit of PCR-LFI assay was 20 fg for genomic DNA (100 times more sensitive than gel electrophoresis) and 2 × 100 CFU per 100 g of pork products after enrichment at 37 °C for 48 h. The total detection time of using LFI was 3 min, which was faster than the conventional electrophoresis (~ 45 min). With the performance of PCR-LFI, 7 out of 42 S. aureus isolates were identified to be MRSA from imported pork products, which was consistent to the standardized minimum inhibitory concentration assay. This mecA-based PCR-LFI strip can be used for rapid and accurate detection of MRSA isolated from commercial pork products.
Co-reporter:Hongyan Zhang, Yan Zhang, Shuo Wang
Journal of Immunological Methods (20 August 2008) Volume 337(Issue 1) pp:1-6
Publication Date(Web):20 August 2008
DOI:10.1016/j.jim.2008.04.015
Two formats of membrane-based competitive enzyme immunoassays (flow-through and dip-stick) have been developed for the screening of sulfonamide residues in pig muscle and milk. Membrane was coated with anti-sulfonamide antibody and a sulfonamide hapten D2-horseradish peroxidase (HRP) conjugant was used as the labeled antigen for competitive assay of sulfonamides. Visual detection limits of the flow-through or dip-stick assay were 1–5 µg L− 1 or 1–10 µg L− 1 in buffer for seven sulfonamides, respectively. Assay validation was performed using samples spiked with single sulfonamide, spiked samples were tested using the developed strip assays and results were compared with those obtained by a validated high-performance liquid chromatograph (HPLC) method. Results showed that the two strip assays were correlated well with HPLC, respectively. With assay times of 5 min (flow-through) and 15 min (dip-stick), these rapid tests could offer simple, rapid and cost-effective on-site screening tools to detect sulfonamides in pig muscle(flow-through or dip-stick) or milk(only dip-stick).
Co-reporter:Junping Wang, Xinfang Xie, Jinsong Feng, Jessica C. Chen, Xin-jun Du, Jiangzhao Luo, Xiaonan Lu, Shuo Wang
International Journal of Food Microbiology (2 July 2015) Volume 204() pp:66-74
Publication Date(Web):2 July 2015
DOI:10.1016/j.ijfoodmicro.2015.03.021
•Raman spectroscopy could detect L. monocytogenes directly from milk.•The classification accuracies were higher than 90%.•Analysis could be finished within a few hours without bacterial enrichment.•Sample preparation was extremely simple.Listeria monocytogenes is a facultatively anaerobic, Gram-positive, rod-shape foodborne bacterium causing invasive infection, listeriosis, in susceptible populations. Rapid and high-throughput detection of this pathogen in dairy products is critical as milk and other dairy products have been implicated as food vehicles in several outbreaks. Here we evaluated confocal micro-Raman spectroscopy (785 nm laser) coupled with chemometric analysis to distinguish six closely related Listeria species, including L. monocytogenes, in both liquid media and milk. Raman spectra of different Listeria species and other bacteria (i.e., Staphylococcus aureus, Salmonella enterica and Escherichia coli) were collected to create two independent databases for detection in media and milk, respectively. Unsupervised chemometric models including principal component analysis and hierarchical cluster analysis were applied to differentiate L. monocytogenes from Listeria and other bacteria. To further evaluate the performance and reliability of unsupervised chemometric analyses, supervised chemometrics were performed, including two discriminant analyses (DA) and soft independent modeling of class analogies (SIMCA). By analyzing Raman spectra via two DA-based chemometric models, average identification accuracies of 97.78% and 98.33% for L. monocytogenes in media, and 95.28% and 96.11% in milk were obtained, respectively. SIMCA analysis also resulted in satisfied average classification accuracies (over 93% in both media and milk). This Raman spectroscopic-based detection of L. monocytogenes in media and milk can be finished within a few hours and requires no extensive sample preparation.
Co-reporter:Hongwei Zhang, Shaolong Feng, Yulong Zhao, Shuo Wang, Xiaonan Lu
International Journal of Food Microbiology (2 December 2015) Volume 214() pp:77-82
Publication Date(Web):2 December 2015
DOI:10.1016/j.ijfoodmicro.2015.07.030
•CPA-immunoblotting analysis could detect Y. enterocolitica in milk powder.•Limit of detection was 100 CFU per 100 g milk powder with pre-enrichment.•Detection could be finished within 90 min after pre-enrichment at 63 °C for 24 h.•Detection result was visible.Yersinia enterocolitica (Y. enterocolitica) is frequently isolated from a wide variety of foods and can cause human yersiniosis. Biochemical and culture-based assays are common detection methods, but require a long incubation time and easily misidentify Y. enterocolitica as other non-pathogenic Yersinia species. Alternatively, cross-priming amplification (CPA) under isothermal conditions combined with immunoblotting analysis enables a more sensitive detection in a relatively short time period. A set of specific displacement primers, cross primers and testing primers was designed on the basis of six specific sequences in Y. enterocolitica 16S–23S rDNA internal transcribed spacer. Under isothermal condition, amplification and hybridization were conducted simultaneously at 63 °C for 60 min. The specificity of CPA was tested for 96 different bacterial strains and 165 commercial milk powder samples. Two red lines were developed on BioHelix Express strip for all of the Y. enterocolitica strains, and one red line was shown for non-Y. enterocolitica strains. The limit of detection of CPA was 100 fg for genomic DNA (1000 times more sensitive than PCR assay), 101 CFU/ml for pure bacterial culture, and 100 CFU per 100 g milk powder with pre-enrichment at 37 °C for 24 h. CPA combined with immunoblotting analysis can achieve highly specific and sensitive detection of Y. enterocolitica in milk powder in 90 min after pre-enrichment.
Co-reporter:Xingxing He, Fuyuan Zhang, Lin Zhang, Qiang Zhang, Guozhen Fang, Jifeng Liu, Shuo Wang and Shuqiu Zhang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 26) pp:NaN5233-5233
Publication Date(Web):2017/06/08
DOI:10.1039/C7TB01426K
The remarkable catalytic properties of enzymes contribute to their unique 3D structures and arrangement of amino acid residues, which provide a blueprint for the design of artificial enzymes. Here, a series of peptide catalysts (PCs) that mimic the unique orientation and function of β-glycosyl hydrolases were designed. Transmission electron microscopy (TEM), fluorescence analysis, circular dichroism spectroscopy, X-ray diffraction and computational modeling were used to investigate and compare the relationship of the fibrinous structure of PCs with its glycoside hydrolysis activity. These results indicated that the catalytic activity of PCs was not only related to their amyloid-like structures, but it can also be influenced by the site, species, molecular arrangement and steric hindrance of the amino acid sequence. What's more, this is the first report on peptide-inspired catalysts that mimic the natural cellobiose hydrolases. All this provided insights into the potential use of peptide nanoenzymes in the generation of efficient artificial enzymes.
Co-reporter:Qiliang Deng, Jianhua Wu, Yang Chen, Zhijun Zhang, Yang Wang, Guozhen Fang, Shuo Wang and Yukui Zhang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 8) pp:NaN1058-1058
Publication Date(Web):2013/12/06
DOI:10.1039/C3TB21540G
Phosphorylation of protein regulates nearly all biological processes in nature. The development of enrichment techniques for phosphorylated proteins is vital to systematic identification and characterization of phosphoproteins. Here, a general strategy for highly efficient capture of intact phosphorylated proteins from protein mixtures has been developed by using guanidine functionalized superparamagnetic microspheres (denoted as Fe3O4@SiO2@GDN). The Fe3O4@SiO2@GDN was prepared by modifying Fe3O4@SiO2 with 3-guanidopropyl triethoxysilane as a functionalization monomer. The resulting materials could specifically and selectively recognize phosphoproteins and showed high binding capacities for model phosphoproteins (78.8 mg g−1 for ovalbumin (OVA) and 59.6 mg g−1 for β-casein (β-Cas), respectively). The feasibility of the resulting material for phosphoprotein enrichment has also been demonstrated by selectively binding and capturing phosphoproteins from complex protein mixtures and real samples (milk, egg, and tissue protein extract from a mouse liver), respectively. In addition, the selective enrichment of phosphopeptides has also been investigated. The proposed technique showed application potential for phosphoprotein and phosphopeptide enrichment.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 17) pp:
Publication Date(Web):
DOI:10.1039/C3AY40131F
A highly reliable and accurate indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed for the detection of streptomycin (STR) in animal-derived foods. The half-maximum inhibition concentration (IC50) of the icELISA for STR was 2.00 ng mL−1 and the limit of detection (LOD, calculated as the IC15 value) was 0.24 ng mL−1. The cross-reactivities with other aminoglycoside antibiotics were very low except for dihydrostreptomycin (95.50%). The recoveries for all samples at five levels (15, 30, 120, 300, 600 ng g−1) ranged from 71.32% to 106.94%. The coefficients of variation of intra- and inter-assays were below 14%. There was a good correlation (R2 = 0.9854) between the data determined by this ELISA and the commercial kit. The analysis of variance of the recoveries showed the sufficiently high stability of the assay to STR in eight animal-derived foods (chicken, pork, chicken liver, pig liver, pig kidney, fish, shrimp, and cow milk). The ELISA allows for a rapid, low-cost, sensitive and accurate determination of STR residues in animal-derived foods.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 21) pp:
Publication Date(Web):
DOI:10.1039/C3AY41083H
In this research, a novel dummy molecularly imprinted polymer (DMIP) was prepared through a sol–gel process using bisphenol A as the dummy template and the synthesized 1-(triethoxysilyl) propyl-3-aminopropyl imidazole bromide (SilprImN) as the functional monomer. The prepared SilprImN-DMIP was characterized by FT-IR and verified with a satisfied identification and penetration performance to bisphenol A in static and kinetic adsorption tests. Furthermore, this novel DMIP was applied as a solid-phase extraction (SPE) material to develop a method for the simultaneous determination of nine organochlorine pesticides (OCPs) in environmental and food samples coupled to a multi dimensional gas chromatograph-mass spectrometer system. The SPE parameters, including sample acidity (pH), sample loading rate, the eluent and elution volume, were optimized in detail to achieve a good extraction efficiency. In water, rice and tea leaf samples spiked with nine OCPs, the OCPs were simultaneously determined with suitable recoveries from 65.65% to 129.61% and a good relative standard deviation (n = 3) of 0.91%–11.47%, indicating the satisfied accuracy and precision of the developed method.
Co-reporter:Cuicui Liu, Qiliang Deng, Guozhen Fang, Xuan Huang and Shuo Wang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 32) pp:NaN5237-5237
Publication Date(Web):2014/06/16
DOI:10.1039/C4TB00663A
Glycoproteins, as low-abundance proteins in organisms, play a critical role in numerous biological processes such as signal transduction, cell differentiation, cellular adhesion, immune defense and embryonic development. Thus, the development of enrichment techniques for glycoproteins is of great importance. In this study, a thiol graphene (TG) doped poly[ionic liquid (ViOcIm+Cl−)] boronate affinity monolithic material was prepared in a single step. The recognition property of the resulting material was evaluated by capillary electrochromatography. The results indicated that the affinity material exhibited specific capture toward cis-diol-containing catechol and glycoproteins at buffer pH as low as 4.0, showing wide pH applications. The large specific surface area (133.64 m2 g−1) of the current monolithic material gave rise to high binding capacities (11.54 mg g−1 for ovalbumin and 10.82 mg g−1 for horseradish peroxidase). The practicability of the resulting monolithic material was further evaluated by specific recognition and enrichment of glycoproteins from egg white and human serum samples, demonstrating its potential for separation and enrichment of glycoproteins from complex biological samples.
Co-reporter:Huilin Liu, Guozhen Fang, Changmo Li, Mingfei Pan, Cuicui Liu, Chao Fan and Shuo Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 37) pp:NaN19887-19887
Publication Date(Web):2012/08/08
DOI:10.1039/C2JM33522K
A new molecularly imprinted polymer (MIP), which acts as a fluorescence nano-sensing material, has been developed for the highly selective and sensitive optosensing of tocopherol (TP). The material was constructed by anchoring the MIP layer on 1-vinyl-3-octylimidazolium ionic liquid (IL)-modified CdSe/ZnS quantum dots (QDs) by copolymerization. Here, the IL was first introduced to the surface of the QDs using a one-step modification of the electrostatic interactions to prepare uniform MIPs. The MIP fluorescence was more strongly quenched by TP than the non-imprinted polymer was, which indicated that the QDs@IL@MIP could recognize the corresponding TP without the need for inducers and derivatization.
Co-reporter:Zhenjuan Duan, Guozhen Fang, Mingfei Pan, Jianghua Yi, Lipeng Fan, Wei Liu and Shuo Wang
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 8) pp:NaN1827-1827
Publication Date(Web):2011/07/04
DOI:10.1039/C1AY05011G
Veterinary antibiotics are environmental contaminants of recent concern, so this study was designed to develop an analytical method of simultaneous determination for quinoxaline-1,4-dioxides (QdNOs) and their metabolites in the aqueous environment at trace levels. The new method is based on on-line solid phase extraction (SPE) using cigarette filter (CGFR) as the sorbent coupled to high-performance liquid chromatography (HPLC). Five QdNOs (carbadox, olaquindox, cyadox, mequindox, quinocetone) and two major metabolites (quinoxaline-2-carboxylic acid and methyl-3-quinoxaline-2-carboxylic acid) were detected in the surface water. The cleaned CGFR precolumn selectively retained target analytes when untreated water samples were upload by a flow-inject pump. Then the enriched extracts were subsequently eluted by HPLC mobile phase to the analytical column for chromatographic analysis. The on-line setup was uncomplicated and automated. The on-line SPE conditions were optimized in detail including sample pH, sample loading flow rate, sample volume, eluent, elution time and sorbents. Under the optimal experimental conditions, the enrichment factors were 33.3–630.0 by preconcentrating 25.0 mL of water samples. Limits of detection (S/N = 3) ranged from 1.6 to 24.3 ng L−1. Satisfactory recoveries were obtained and ranged from 87.1 to 107.5% at two spiked levels in real water samples with high precision (RSD, 1.3–3.8%). The on-line SPE-HPLC method is simple, rapid, reliable, sensitive and could be applied for multiresidue determination of the QdNOs and their metabolites in water samples.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 21) pp:NaN5943-5943
Publication Date(Web):2013/08/20
DOI:10.1039/C3AY40825F
A simple and sensitive enhanced chemiluminescence enzyme linked immunosorbent assay (ECL-ELISA) has been developed for the detection of phosmet (PMT), azinphos-methyl (APM) and azinphos-ethyl (APE) residues in vegetable samples. The concentration of the coating antibody and enzyme tracer as well as the effects of the pH value, ionic strength and organic solvent were studied. The measured sensitivities (IC50) of PMT, APM and APE were 8.56, 9.04 and 25.34 μg L−1, respectively. High throughput screening for PMT, APM, and APE residues was achieved with good accuracy by means of the ECL-ELISA. The measurement time of the ECL-ELISA method was 5–10% shorter than that of the traditional ELISA method, and the sensitivity of detection was 2–3.5 times lower than that of the traditional method.
Co-reporter:Shifang Yuan, Qiliang Deng, Guozhen Fang, Mingfei Pan, Xiaorui Zhai and Shuo Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 9) pp:
Publication Date(Web):
DOI:10.1039/C2JM14577D
Co-reporter:Kun Qian, Guozhen Fang and Shuo Wang
Chemical Communications 2011 - vol. 47(Issue 36) pp:NaN10120-10120
Publication Date(Web):2011/08/08
DOI:10.1039/C1CC12935J
A novel core–shell molecularly imprinted polymer is firstly prepared by coating the MIP shell onto the surface of the metal–organic framework, which shows a homogeneous polymer film, cubic shape, thermal stability, and exhibits a higher specific surface area and a faster transfer-mass speed compared with that of the bulk MIP.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 20) pp:
Publication Date(Web):
DOI:10.1039/C3AY40880A
This paper describes the development of a direct competitive enzyme-linked immunosorbent assay with a molecularly imprinted film as an artificial antibody to measure trace tribenuron-methyl (TBM) in environmental water and soil samples. The molecularly imprinted film was directly synthesized on the well surface of a MaxiSorp polystyrene 96-well plate by a non-covalent approach, and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and static and kinetic adsorption experiments. Under optimum conditions, the IC50 and IC15 of the established method are 19.73 μg L−1 and 0.30 μg L−1, respectively, and its cross-reactivity with three sulfonylurea herbicides is in the range of 3.17–13.10%. The method was successfully applied to the determination of TBM in spiked environmental water and soil samples with recoveries from 93.6 to 96.8% and 87.5 to 97.5%, respectively. The results are in good agreement with those obtained by high performance liquid chromatography.
Co-reporter:Qiliang Deng, Yanli Li, Jianhua Wu, Yang Liu, Guozhen Fang, Shuo Wang and Yukui Zhang
Chemical Communications 2012 - vol. 48(Issue 24) pp:NaN3011-3011
Publication Date(Web):2012/01/17
DOI:10.1039/C2CC17856G
Fluorescent conjugated polymer, poly(3-aminobenzoic acid), as a new class of fluorescence sensor for detection of trace amounts of water in organic solvents was developed. This sensor exhibits extraordinarily high sensitivity with a detection limit as low as 0.008 wt% for water in DMF.
Co-reporter:Xuan Huang, Junping Wang, Cuicui Liu, Ting Guo and Shuo Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 12) pp:NaN2515-2515
Publication Date(Web):2015/02/06
DOI:10.1039/C4TB01899K
A novel rGR–TiO2–ZrO2 (rGTZ) composite nanosheet comprising graphene oxides, tetrabutyl titanate, and zirconium(IV) isopropoxide was synthesized using a simple sol–gel method and hydrothermal treatment. The excellent surface area of graphene and the specificity of TiO2 and ZrO2 toward phosphopeptides were integrated to form a composite with a high number of specific sites for the capture of phosphopeptides from complex biosamples. The average diameter of the nanoparticles that were loaded onto the flat graphene surface was 100 nm, according to a TEM analysis. The adsorption behaviors of the materials were evaluated using the Langmuir model equation, and the Qmax values of the commercial TiO2, GTZ, and rGTZ were calculated to be 373.1 mg g−1, 250.0 mg g−1 and 490.2 mg g−1. Beta-casein was applied as a standard protein to optimize the conditions for phosphopeptide enrichment. Different materials (GTZ and commercial TiO2) were used to demonstrate the superiority of the rGTZ composite nanosheet for capturing phosphopeptides from tryptic digests of β-casein under the optimized conditions. Various complex samples (α-casein, mixtures of β-casein and bovine serum albumin, which were used as examples of semi-complex samples, non-fat milk, and mouse organs) were exploited to evaluate the capabilities and efficiency of the rGTZ nanosheet composite. 1980 phosphopeptides from 1769 proteins from mouse brain and 577 phosphopeptides from 1267 proteins from mouse liver were identified by their enrichment in mouse brain and liver using rGTZ nanosheet composites.
Co-reporter:
Analytical Methods (2009-Present) 2015 - vol. 7(Issue 20) pp:NaN8625-8625
Publication Date(Web):2015/09/08
DOI:10.1039/C5AY02021B
Speciation analysis of arsenic (As) and selenium (Se) in foods is of great significance for human health. In this paper, a novel ionic liquid improved reversed phase high performance liquid chromatography (RP-HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) method was developed for the simultaneous determination of six As species and four Se species. To enhance the detection sensitivity, the RP-HPLC-ICP-MS determination conditions were systematically optimized. Under the optimal conditions, good linearity ranging from 2.5 to 400 μg L−1 was obtained. The limits of detection (LODs) were 0.34–0.86 μg L−1 for the As species and 0.94–1.52 μg L−1 for the Se species. The recoveries of the As and Se species in animal/plant-derived samples (pork, chicken, rice and wheat) were in the range of 71.5–107.5% and 70.2–123.4%, respectively. These results demonstrated that the current method is promising for the accurate quantification of the As and Se species in foods.
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