Co-reporter:Qian Luan, Ning Gan, Yuting Cao, and Tianhua Li
Journal of Agricultural and Food Chemistry July 19, 2017 Volume 65(Issue 28) pp:5731-5731
Publication Date(Web):June 27, 2017
DOI:10.1021/acs.jafc.7b02139
A mimicking-enzyme-based colorimetric aptasensor was developed for the detection of kanamycin (KANA) in milk using magnetic loop-DNA-NMOF-Pt (m-L-DNA) probes and catalytic hairpin assembly (CHA)-assisted target recycling for signal amplification. The m-L-DNA probes were constructed via hybridization of hairpin DNA H1 (containing aptamer sequence) immobilized magnetic beads (m-H1) and signal DNA (sDNA, partial hybridization with H1) labeled nano Fe-MIL-88NH2-Pt (NMOF-Pt-sDNA). In the presence of KANA and complementary hairpin DNA H2, the m-L-DNA probes decomposed and formed an m-H1/KANA intermediate, which triggered the CHA reaction to form a stable duplex strand (m-H1-H2) while releasing KANA again for recycling. Consequently, numerous NMOF-Pt-sDNA as mimicking enzymes can synergistically catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) for color development. The aptasensor exhibited high selectivity and sensitivity for KANA in milk with a detection limit of 0.2 pg mL–1 within 30 min. The assay can be conveniently extended for on-site screening of other antibiotics in foods by simply changing the base sequence of the probes.Keywords: antibiotics residue detection in milk; CHA assisted signal amplification; colorimetric aptasensor; loop DNA; NMOF-Pt mimicking enzyme;
Co-reporter:Haibo Liu;Yinji Chen;Tianhua Li;Yuting Cao
RSC Advances (2011-Present) 2017 vol. 7(Issue 12) pp:6800-6808
Publication Date(Web):2017/01/20
DOI:10.1039/C6RA27005K
In this study, a novel three dimensional (3D) M × N type aptamer-functionalized solid-phase micro extraction (SPME) fibers array (M represents the number of targets; N represents the number of samples) was developed for selective enrichment of multiplex antibiotic residues from milk samples, with three chloramphenicols (CAPs) as models. First, gold nanoparticles (AuNPs) were electrodeposited on a gold wire (Φ = 0.2 mm), which was wound around a conductive indium tin oxide (ITO) glassy fiber. Then, the fiber was immersed into thiol-functionalized aptamer solution, which could specifically recognize three CAPs, including chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF). The aptamer can be covalently immobilized on AuNPs through Au–S bonds. Thus, a 3D aptamer-functionalized fiber interface (3D-Apt@AuNPs@Au wire–ITO) was built and employed for specifically sorptive extraction of CAPs from the milk samples with a matrix complex based on the high affinity of the aptamer for the targets. The extraction capacities for CAP, TAP and FF were 887, 840 and 801 ng per fiber, respectively. The enrichment folds were more than 500 times, which is 3.1 folds higher than that of the 2D-Apt@AuNPs–ITO fiber and 6.6 folds higher than that of the 1D-Apt@Au wire–ITO fiber. Afterwards, several similar fibers were assembled together into an array for simultaneous enrichment of three CAPs from 12 samples in one run. Finally, the adsorbed targets were washed away using a pH 8.5 0.1 M Tris–HCl buffer and then detected by high performance liquid chromatography (HPLC)-Diode Array Detector (DAD). The parameters, including extraction temperature, shuttle rates, extraction and desorption pH, and extraction and desorption time, were investigated and discussed. Under the optimized conditions, the limits of detection (LOD) and quantitation (LOQ) were determined as 0.262–0.293 and 0.864–0.967 ng mL−1, respectively, for several CAPs. The fibers array can be applied in replicate batch-extraction for at least 60 extraction cycles with a recovery of over 80%. The SPME fibers assay coupled with HPLC detection possessed advantages of high-throughput, high selectivity and adsorption capacity in one run. Furthermore, the process is environmentally friendly without using organic solutions during the entire extraction process. Thus, the method is a universal platform that can be extended to the selective extraction of other organic pollutant residues if the modified aptamers are changed.
Co-reporter:Caiye wu;Changrong Ou;Haiqing Tang;You Zhou;Jinxuan Cao
RSC Advances (2011-Present) 2017 vol. 7(Issue 14) pp:8381-8387
Publication Date(Web):2017/01/23
DOI:10.1039/C6RA27337H
A novel fluorescent “signal-on” switch aptasensor based on a single stranded DNA binding protein (SSB) labeled quantum and exonuclease-assisted target recycling was designed for detecting antibiotics in homogeneous media. In this assay, streptomycin (STR) was employed as a model and the fluorescent probe was synthesized by labeling SSB on quantum dots (QDs–SSB). The SSB can specifically bind an aptamer. When an aptamer serving as a bridging ligand is added, it can hybrid with SSB. Meanwhile, the quantum dots dispersed in the solution were aggregated, which resulted in self-quenching of the QDs' fluorescence and its intensity decreased sharply and switched from “on” to “off”. When the fluorescent probe coexisted with STR and Exo I, the aptamer preferentially bound with a target, and the aptamer-target was digested into mononucleotides by Exo I. Then the liberated target could be further involved in the reaction cycling to produce a strong fluorescence signal. Consequently, the distance of QDs increased and the fluorescence intensity was recovered. Thus, the switch changed from the “off” state to “on”. Under optimized conditions, the assay indicates good linear relationship in a range from 0.1 to 100 ng mL−1 and the detection limit of STR was 0.03 ng mL−1 (S/N = 3). And after 8 times of detecting streptomycin, the fluorescence intensity of the system was still able to reach the initial 90.19% efficiency. In addition, this type of switch fluorescent probe provides a simple and specific approach for antibiotics detection especially suitable for a homogeneous system.
Co-reporter:Meng Chen, Ning Gan, Tianhua Li, Ye Wang, Qing Xu, Yinji Chen
Analytica Chimica Acta 2017 Volume 968(Volume 968) pp:
Publication Date(Web):22 May 2017
DOI:10.1016/j.aca.2017.03.024
•A multiplex antibiotics aptsensor was developed based on Y- shaped DNA probes and CRSP amplification scheme.•The Y- shaped DNA probe was made by metal ions encoded NMOFs for signal distinction.•The CRSP polymerization was introduced for target-triggered amplification.An effective electrochemical aptasensor has been developed for the detection of multiplex antibiotics using Y-shaped DNA probes. These probes-based metal ions encoded the nanoscale metal-organic frameworks (NMOF) as a substrate, and circular strand-replacement DNA polymerization (CSRP) target triggered the amplification strategy. The Y-DNA probes (Y-DNA) were assembled using an assisted DNA probe (assisted DNA labeled with magnetic gold nanoparticles) which can hybridize to the captured DNA probe (consisting of aptamer and primer recognition region), and signal tags (NMOF encapsulating signal DNAs and different metal ions such as Pb2+ or Cd2+). Notably, NMOF was employed as the developed platform with a large specific area to load abundant metal ions that can produce distinguishable signals. In the presence of targets, chloramphenicol (CAP) and oxytetracycline (OTC) as models, the conformational change of the captured DNA can disassemble the Y-DNA probes that can consequently release the signal tags in the supernatant due to the high affinity of targets towards the aptamer domain than its complementary sequences. Subsequently, the exposed sequences of captured DNA serve as the initiators for triggering the target cyclic-induced polymerization with the assistance of Bst DNA polymerase. Thus, numerous signal tags could be detected by square wave voltammetry in the supernatant after magnetic separation, thereby amplifying the electrochemical signals. The proposed strategy exhibited a high sensitivity to antibiotics with a detection limit of 33 and 48 fM (S/N = 3) towards CAP and OTC, respectively. Moreover, this aptasensor showed promising applications for the detection of other analytes.Download high-res image (192KB)Download full-size image
Co-reporter:Ye Wang, Ning Gan, You Zhou, Tianhua Li, Futao Hu, Yuting Cao, Yinji Chen
Biosensors and Bioelectronics 2017 Volume 97(Volume 97) pp:
Publication Date(Web):15 November 2017
DOI:10.1016/j.bios.2017.05.017
•A method based on MCE and CHA amplification was developed for multiplex antibiotics detection.•The probes can transduce targets to DNA signals, which can be amplified by CHA then detected by MCE.•The assay exhibits high sensitivity and selectivity for target molecules.•The assay was successfully employed for detection of kana and OTC in milk.Novel label-free and multiplex aptasensors have been developed for simultaneous detection of several antibiotics based on a microchip electrophoresis (MCE) platform and target catalyzed hairpin assembly (CHA) for signal amplification. Kanamycin (Kana) and oxytetracycline (OTC) were employed as models for testing the system. These aptasensors contained six DNA strands termed as Kana aptamer-catalysis strand (Kana apt-C), Kana inhibit strand (Kana inh), OTC aptamer-catalysis strand (OTC apt-C), OTC inhibit strand (OTC inh), hairpin structures H1 and H2 which were partially complementary. Upon the addition of Kana or OTC, the binding event of aptamer and target triggered the self-assembly between H1 and H2, resulting in the formation of many H1-H2 complexes. They could show strong signals which represented the concentration of Kana or OTC respectively in the MCE system. With the help of the well-designed and high-quality CHA amplification, the assay could yield 300-fold amplified signal comparing that from non-amplified system. Under optimal conditions, this assay exhibited a linear correlation in the ranges from 0.001 ng mL−1 to 10 ng mL−1, with the detection limits of 0.7 pg mL−1 and 0.9 pg mL−1 (S/N=3) toward Kana and OTC, respectively. The platform has the following advantages: firstly, the aptamer probes can be fabricated easily without labeling signal tags for MCE detection; Secondly, the targets can just react with probes and produce the amplified signal in one-pot. Finally, the targets can be simultaneously detected within 10 min in different channels, thus high-throughput measurement can be achieved. Based on this work, it is estimated that this detection platform will be universally served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.
Co-reporter:Fangying Lv, Ning Gan, Yuting Cao, You Zhou, Rongjie Zuo, Youren Dong
Journal of Chromatography A 2017 Volume 1525(Volume 1525) pp:
Publication Date(Web):24 November 2017
DOI:10.1016/j.chroma.2017.10.026
•A novel MoS2/RGO coating for efficiently extraction and determination of PCBs was developed via a saponification-HS-SPME.•Alkali solution was employed to help release PCBs from food, thus no organic solvents are needed for extraction.•The method exhibited high sensitivity, wide linearity and good precision for PCBs than commercial SPME.In this work, the molybdenum disulfide/reduced graphene oxide (MoS2/RGO) composite material was synthesized as a fiber coating to extract seven indicator polychlorinated biphenyls (PCBs; PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) present in food via a saponification-headspace solid-phase microextraction assay (saponification-HS-SPME). The MoS2/RGO coating was prepared and deposited on a stainless steel wire with the help of a silicone sealant and used as an SPME fiber. The alkali solution dissolved the fat and helped in releasing the PCBs present in milk to the headspace for extraction under 100 °C. Following desorption in the inlet, the targets were quantified by gas chromatography-mass spectrometry. The effects of sorbent dosage, extraction time, added salts, and stirring rate on the extraction efficiency were investigated. The new coating was able to adsorb a higher amount of analytes, which was about 1.1–2.9 times in comparison with the commercially available SPME fiber (coated with divinylbenzene/carboxen/polydimethylsiloxane). It also showed the highest adsorption capability toward PCBs, which was 1.5–2.7 times that of the prepared RGO modified fiber. Moreover, MoS2 also showed a strong affinity toward PCBs in a manner similar to its affinity for graphene. The developed method is simple and environmentally friendly as it does not require any organic solvents. Furthermore, it exhibits good sensitivity with detection limits less than 0.1 ng mL−1, linearity (0.25–100 ng mL−1), and reproducibility (relative standard deviation below 10% for n = 3). The novel SPME fibers are inexpensive, reusable, and can be easily prepared and manipulated. In addition, the saponification-HS-SPME assay was also found to be suitable for screening persistent organic pollutants in dairy products.
Co-reporter:Shengfeng Huang, Ning Gan, Haibo Liu, You Zhou, Yinji Chen, Yuting Cao
Journal of Chromatography B 2017 Volume 1060(Volume 1060) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.jchromb.2017.05.035
•A novel aptamer functionalized magnetic adsorbent was developed for selective enrichment of three amphenicols in complex food matrix.•Dispersive solid phase extraction method coupling with the adsorbent was employed for detection 0.1 ng/ml of amphenicols in milk.•This assay is environmentally friendly and time-saving due to without using organic reagent and purifying.In this work, a novel aptamer functionalized magnetic adsorbent was developed and combined with magnetic dispersive solid phase extraction (MDSPE) for selective enrichment of several amphenicol antibiotics residues (chloramphenicol(CAP), thiamphenicol(TAP) and florphenicol(FF)) in foodstuff then determined by High Performance Liquid Chromatography (HPLC)-Diode array detector(DAD). Firstly, a magnetic silica-coated Fe3O4 microsphere(Fe3O4@SiO2) was synthetized by sol-gel method, then it was functionalized by amino groups through 3-Aminopropyltriethoxysilane (APTES) reagent to form Fe3O4@SiO2-NH2; Thirdly, the amino group on Fe3O4@SiO2-NH2 was transferred to carboxylic group via the succinic anhydride to form Fe3O4@SiO2-COOH. Finally a kind of DNA aptamer with amino group which can simultaneously recognize CAP, TAP, FF, was functionalized on Fe3O4@SiO2-COOH through adding the EDC/sulfo-NHS coupling reagent (Fe3O4@SiO2@Apt). Therefore, a very stable and useful adsorbent was synthesized for the detection of chloramphenicol series antibiotics. This adsorbent can specifically and simultaneously recognize and enrich CAP, TAP, and FF with high adsorption amount from some complicated food matrix, e.g. milk based on the high affinity of aptamer towards the analytes. The saturated extraction capacities for CAP, TAP and FF by the adsorbent were 2.82, 2.56, 2.72 μg/g (mass of target/adsorbent)respectively and the enrichment folds were more than 100 times. Afterwards, the target analytes were washed away by pH 8.5 0.1 M Tris-HCl buffer solution and detected by HPLC-DAD. The parameters including extraction temperature, extraction capacity, extraction & desorption pH, extraction & desorption time were investigated. With the optimized conditions, the limits of detection (LOD) and limits of quantitation (LOQ) were 0.12–0.17 ng/ml and 0.40–0.55 ng/ml for the amphenicols in milk. The adsorbent also has good reproducibility for extraction which can be reused at least for 60 cycles with the recovery over 80% (Fig. S2). The MDSPE combined with HPLC-DAD detection possessed the advantages of high selectivity, extraction capacity and very convenient for magnetic separation. In addition, this method is environment friendly and employed no organic solution in the period of pretreatment and extracting. It is a universal platform which can be extended to selective enrichment other organic pollutants residues if changing the modified aptamers.
Co-reporter:Qian Luan, Yangbao Miao, Ning Gan, Yuting Cao, Tianhua Li, Yinji Chen
Sensors and Actuators B: Chemical 2017 Volume 251(Volume 251) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.snb.2017.04.149
•An ultrasensitive colorimetric aptasensor for streptomycin detection has developed.•This probe was fabricated through porous silica (P-SiO2-SSB) labeled aptamer-nano gold -powervision as signal tags.•The strategy can achieve multiplex signal amplification based on the P-SiO2, PV and Exo I-assisted target recycling.•The aptasensor is easy to operate, rapid and sensitive for POCT detection of antibiotics.A point of care testing (POCT) colorimetric aptasensor was developed to detect streptomycin (STR) using porous SiO2 micro beads (pore size of 200 nm) −enzyme linked polymer (PowerVision™, PV) probes and exonuclease-assisted target recycling for signal amplification. The probe was fabricated by single- stranded DNA binding protein labelled SiO2 micro particles (P-SiO2-SSB) as capture probes and Au NPs & aptamer (Apt) co-immobilized on PV (Apt-Au-PV) as nanotracer. In the presence of STR and exonuclease I (Exo I), the nanotracer would combine with STR to form the complex (STR/Apt-Au-PV). Hereafter, Exo I further digest the aptamer on STR/Apt-Au-PV, then STR was released again to participate new cycling, the approach lead to generate more nanotracers into supernatant to improve the sensitivity. Moreover, the dendrimer PV which contains large quantities of HRPs can efficiently catalyzed H2O2-TMB (3,3′,5,5′- tetramethylbenzidine) system for color development and the results can observed by the naked eye. Due to the excellent multiple signal amplification effects for porous SiO2 micro particles to label more nanotracer, PV and exonuclease-assisted target recycling, the aptasensor exhibit a low detection limit with 1 pg mL−1 (S/N = 3). In addition, the developed method might provide a prospect assay for food tests at point of care.Download high-res image (116KB)Download full-size image
Co-reporter:Jie Huang, Changrong Ou, Fangying Lv, Yuting Cao, Haiqing Tang, You Zhou, Ning Gan
Talanta 2017 Volume 165() pp:326-331
Publication Date(Web):1 April 2017
DOI:10.1016/j.talanta.2016.12.075
•A facile on-fiber derivatization SPME assay was used for direct extraction of aliphatic amines in aqueous fish samples.•The derivatization reagent was loaded into the ZIF-8 coating which can prevent its hydrolysis.•ZIF-8 which possesses high surface area and porous nature can load enormous amount of reagent to increase the sensitivity.•The whole extraction process is environment friendly and easy to manipulate for analysis of fish samples.Some harmful aliphatic diamines, e.g., putrescine (Put) and cadaverine (Cad), play important roles in food safety evaluation. In this study, we proposed on-fiber derivatization solid-phase microextraction analysis of non-volatile aliphatic diamines in fish using zeolitic imidazolate framework 8 (ZIF-8) as a solid-phase microextraction (SPME) coating. It was employed to encapsulate isobutyl chloroformate (IBCF, 40 °C, 15 min) for aqueous extraction of Put and Cad. After that, the derivatized aliphatic amines were thermally desorbed in the GC injection port and analyzed by GC-MS. The porous and hydrophobic ZIF-8 with high surface area can increase the IBCF loading amount and prevent it from decomposing, thus increasing the amine extraction effectiveness and sensitivity. In SIM mode and using the molecular ion for quantification, the limits of detection for Put and Cad were 27.1 and 33.2 μg L−1, respectively under the optimal conditions. The fiber-to-fiber reproducibility values (RSDs) for three ZIF-8 coated fibers were less than 11.4% for both Put and Cad. The extraction with the new fiber was reproducible for at least 30 cycles without a noticeable decrease of performance (RSD<10%). The new fiber was successfully applied to the detection of putrescine and cadaverine in several fish samples and showed good recoveries (78.6–104%).
Co-reporter:Haibo Liu;Diebate Ousmane;Dazhen Wu;Tianhua Li
Chromatographia 2017 Volume 80( Issue 3) pp:473-482
Publication Date(Web):2017 March
DOI:10.1007/s10337-017-3242-1
This study aimed to simultaneously determine three β2-agonists (clenbuterol, salbutamol, and ractopamine) in pork samples using novel stir bar array sorptive extraction coupled with gas chromatography–mass spectrometry. Pencil refill was employed as the substrate of stir, which was covered with carboxyl graphene sheets and polyluminol coating. The coating was simply prepared by electrochemical deposition of luminol at a voltage of 0–0.6 V. Then, an automatic device with the stir bar array for extraction was used. The conditions for the extraction were optimized. Under the optimum extraction conditions, with toluene as the extraction solvent, the extraction and desorption times were 20 min. A good linearity of three β2-agonists was obtained in the range of 0.5–100 ng g−1 by gas chromatography–mass spectrometry detection. The recovery of clenbuterol, salbutamol, and ractopamine in spiked pork samples ranged from 88.7 to 93.2%, 85.5–94.2%, and 85.7–93.9%, respectively, with the relative standard deviations less than 10%. The detection limits were in the range of 0.022–0.091 ng g−1 for pork samples. The extraction coating with high extraction capacity was simply fabricated by the electrochemical method, which could simplify the pretreatment procedures. Moreover, the array could extract several samples simultaneously and improve the pretreatment efficiency.
Co-reporter:Ye Wang, Ning Gan, You Zhou, Tianhua Li, Yuting Cao, Yinji Chen
Biosensors and Bioelectronics 2017 Volume 87() pp:508-513
Publication Date(Web):15 January 2017
DOI:10.1016/j.bios.2016.08.107
•A propagable SSB assisted FRET fluorescence aptamer switch was developed.•The switch exhibits highly selectivity and good repeatability towards CAP.•The switch turns on after introducing CAP because SSB only combines free aptamer.•This method agrees well with ELISA and has low detection limit of 3 pg mL-1.Herein, a smart single-stranded DNA binding protein (SSB)-assisted fluorescence aptamer switch based on fluorescence resonance energy transfer (FRET) was designed. The FRET switch was synthesized by connecting SSB labeled quantum dots (QDs@SSB) as donor with aptamer (apt) labeled gold nanoparticles (AuNPs@apt) as acceptor, and it was employed for detecting chloramphenicol (CAP) in a homogenous solution. In the assay, the interaction between core-shell QDs@SSB and AuNPs@apt leads to a dramatic quenching (turning off). After adding CAP in the detection system, AuNPs@apt can bind the target specifically then separate QDs@SSB with AuNPs@apt-target, resulting in restoring the fluorescence intensity of QDs (turning on). Consequently, the fluorescence intensity recovers and the recovery extent can be used for detection of CAP in homogenous phase via optical responses. Under optimal conditions, the fluorescence intensity increased linearly with increasing concentrations of CAP from 0.005 to 100 ng mL−1. The limit of this fluorescence aptamer switch was around 3 pg mL−1 for CAP detection. When the analyte is changed, the assay can be applied to detect other targets only by changing relative aptamer in AuNPs@apt probe. Furthermore, it has potential to be served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.
Co-reporter:Yang-Bao Miao, Hong-Xia Ren, Ning Gan, You Zhou, Yuting Cao, Tianhua Li, Yinji Chen
Analytica Chimica Acta 2016 Volume 929() pp:49-55
Publication Date(Web):27 July 2016
DOI:10.1016/j.aca.2016.04.060
•Homogeneous and “off–on” fluorescence aptamer-based assay was developed to detect chloramphenicol (CAP) residues in food.•This probe was fabricated based on a vesicle QDs signal tracer (SSB/L-QD) combining with Au-Aptamer.•The detection mechanism was based on FRET with high specificity.•The results for CAP detection in the milk samples agreed well with those from ELISA, while detection limit down to 0.3 pM.In this work, a novel homogeneous and signal “off–on” aptamer based fluorescence assay was successfully developed to detect chloramphenicol (CAP) residues in food based on the fluorescence resonance energy transfer (FRET). The vesicle nanotracer was prepared through labeling single stranded DNA binding protein (SSB) on limposome-CdSe/ZnS quantum dot (SSB/L-QD) complexes. It was worth mentioning that the signal tracer (SSB/L-QD) with vesicle shape, which was fabricated being encapsulated with a number of quantum dots and SSB. The nanotracer has excellent signal amplification effects. The vesicle composite probe was formed by combining aptamer labeled nano-gold (Au-Apt) and SSB/L-QD. Which based on SSB's specific affinity towards aptamer. This probe can't emit fluoresce which is in “off” state because the signal from SSB/L-QD as donor can be quenched by the Au-aptas acceptor. When CAP was added in the composite probe solution, the aptamer on the Au-Apt can be preferentially bounded with CAP then release from the composite probe, which can turn the “off” signal of SSB/L-QD tracer into “on” state. The assay indicates excellent linear response to CAP from 0.001 nM to 10 nM and detection limit down to 0.3 pM. The vesicle probes with size of 88 nm have strong signal amplification. Because a larger number of QDs can be labeled inside the double phosphorus lipid membrane. Besides, it was employed to detect CAP residues in the milk samples with results being agreed well with those from ELISA, verifying its accuracy and reliability.
Co-reporter:Saichai Lin, Ning Gan, Yuting Cao, Yinji Chen, Qianli Jiang
Journal of Chromatography A 2016 Volume 1446() pp:34-40
Publication Date(Web):13 May 2016
DOI:10.1016/j.chroma.2016.04.016
•Aptamer-functionalized UiO-66-NH2 was applied to selectively extract PCBs.•UiO-66-NH2 used as the substrate to increase adsorption capacity.•Fe3O4@PDA@UiO-66-NH2was prepared without seeding by using PDA as covalent linker.In this paper, a novel dispersive solid phase extraction (dSPE) adsorbent based on aptamer-functionalized magnetic metal-organic framework material was developed for selective enrichment of the trace polychlorinated biphenyls (PCBs) from soil sample. Firstly, we developed a simple, versatile synthetic strategy to prepare highly reproducible magnetic amino-functionalized UiO-66 (Fe3O4@PDA@UiO-66-NH2) by using polydopamine (PDA) as covalent linker. Then amino-functionalized aptamers which can recognize 2,3′,5,5′-tetrachlorobiphenyl (PCB72), 2′,3′,4′,5,5′-pentachlorobiphenyl (PCB106) were covalent immobilized on UiO-66-NH2 through coupling reagent of glutaraldehyde. Aptamer-functionalized adsorbent (Fe3O4@PDA@UiO-66-Apt) can specifically capture PCBs from complex matrix with high adsorption capacity based on the specific affinity of aptamer towards target. Moreover, the adsorbent can be easily isolated from the solution through magnetic separation after extraction. Afterwards, the detection was carried out with gas chromatography tandem mass spectrometry (GC–MS). The selective dSPE pretreatment coupled with GC–MS possessed high selectivity, good binding capacity, stability, repeatability and reproducibility for the extraction of PCBs. Furthermore, the adsorbent possessed good mechanical stability which can be applied in replicate at least for 60 extraction cycles with recovery over 80%. It provided a linear range of 0.02–400 ng mL−1 with a good correlation coefficient (R2 = 0.9994–0.9996), and the limit of detection was found to be 0.010–0.015 ng mL−1. The method was successfully utilized for the determination of PCBs in soil samples.
Co-reporter:Haibo Liu, Jiabin Zhang, Ning Gan, Yinji Chen, Jie Huang, Yuting Cao, Tianhua Li and Hangzhen Lan
RSC Advances 2016 vol. 6(Issue 1) pp:183-189
Publication Date(Web):15 Dec 2015
DOI:10.1039/C5RA21214F
In this study, a highly effective clean-up adsorbent was developed for eliminating matrix interferences, especially main organochlorine pesticide residues during the determination of highly chlorinated polychlorinated biphenyls in seafood. The multifunctional adsorbent was prepared by grafting carboxymethyl-β-cyclodextrin on the surface of amino functionalized mesoporous nanoparticles. The amino group functionalized mesoporous SiO2 can remove most of matrix interference in samples. Moreover, carboxymethyl-β-cyclodextrin has stronger host–guest complexation with 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, 2,2-bis(p-chlorophenyl)-1,1-dichloro-ethylene, and 1,1-dichloro-2,2-bis(p-chloropheny)ethane. However, it showed weaker adsorption ability toward highly chlorinated polychlorinated biphenyls due to a steric hindrance effect. Based on this, a gas chromatography-mass spectrometry method coupled with the multifunctional adsorbent as a clean-up adsorbent for dispersive solid phase extraction was developed for the analysis of several highly chlorinated polychlorinated biphenyls in seafood samples. The results indicate that the multifunctional adsorbent as a purification material can easily and effectively remove matrix interferences in seafood samples within a short time. The recoveries for polychlorinated biphenyls were in the range of 88.4–103.2%, with relative standard deviations varying between 1.3 and 5.7%.
Co-reporter:Ye Wang, Ning Gan, Tianhua Li, Yuting Cao, Futao Hu and Yinji Chen
Analytical Methods 2016 vol. 8(Issue 15) pp:3006-3013
Publication Date(Web):09 Mar 2016
DOI:10.1039/C6AY00412A
Herein, a facile, signal-on and homogenous fluorescence assay using novel aptamer-dsDNA antibody–quantum dot probes was designed for detecting antibiotic residues. In this assay, the fluorescent probes were fabricated by using a double-stranded DNA antibody (dsDNA Ab) covalently bonded on the surface of CdSe quantum dots. The antibody can bind double-stranded DNA (dsDNA) specifically. When dsDNA was added, the fluorescence could be efficiently quenched because the probes came into contact with each other with dsDNA as the bridge. The dsDNA was formed between an aptamer towards chloromycetin (CAP) and its complementary strand DNA (cDNA). When CAP was added into the reaction system, the aptamer reacted with CAP preferentially and the dsDNA was unwinded to single strand DNA (ssDNA) which cannot be recognized by the dsDNA antibody. Thus the probes were separated and fluorescence was recovered. Based on the scheme, a signal-on fluorescence assay for detecting antibiotics in a homogenous aqueous phase was developed. Under the optimized conditions, the assay shows a good liner range from 0.05 ng mL−1 to 100 ng mL−1 and the limit of detection (LOD) is 0.002 ng mL−1. If the analyte is changed, the assay can also be employed only by changing the corresponding aptamer and its cDNA. What's more, the probes can be reused at least 10 times with the recovery above 90%. The fluorescence assay is facile and has promising application for detecting antibiotic contaminants in biological and environmental samples.
Co-reporter:Yang-Bao Miao, Hong-Xia Ren, Ning Gan, Yuting Cao, Tianhua Li, Yijin Chen
Biosensors and Bioelectronics 2016 81() pp: 454-459
Publication Date(Web):15 July 2016
DOI:10.1016/j.bios.2016.03.034
•A novel fluorescence aptasensor was successfully developed to detect chloramphenicol (CAP).•This probe can be fabricated though magnetic vesicle probes.•The vesicle probes can effective amplified signal.•This method for CAP detection in the fish samples agreed well with those from ELISA.A novel fluorescence aptasensor was successfully developed to respond to chloramphenicol (CAP) in food based on magnetic aptamer-liposome vesicle probe. In order to fabricate it, aptamer labeled on functionalized magnetic beads (MB) was firstly employed as capture adsorbent (MB-Apt), then SSB (single-stranded DNA binding protein) and DIL (1,1′-dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanineperchlorate) coimmobilized liposomes (SSB/DIL-Lip) was employed as vesicle signal tracer. The composite vesicle probe is formed between SSB/DIL-Lip and MB-Apt based on SSB's specific recognition towards aptamer on vesicle signal tracer. Upon the vesicle probe solution reacted with CAP, the aptamer on the magnetic beads preferentially bounded with CAP, and then released SSB/DIL-Lip vesicle signal tracer in the supernatant after magnetic separation. The released tracer can emit fluorescence which was correspondence with the concentration of the analyte. At the optimum conditions, the aptasensor exhibited a good linear response for CAP detection in the range of 0.003–10 nM with a detection limit of 1 pM. Importantly, the methodology was further validated for analyzing CAP in fish samples with consistent results obtained by ELISA kit, thus providing a promising approach for quantitative monitoring of CAP and significant anti-interference ability in food safety.
Co-reporter:Xiaobin Feng, Ning Gan, Saichai Lin, Tianhua Li, Yuting Cao, Futao Hu, Qianli Jiang, Yinji Chen
Sensors and Actuators B: Chemical 2016 Volume 226() pp:305-311
Publication Date(Web):April 2016
DOI:10.1016/j.snb.2015.11.131
•Ratiometric ECL aptasensor strategy based on the ratio of working signal to internal standard signal was designed.•L-Au NPs as ECL working tags and CdS QDs as internal standard tags were respectively modified on two spatial resolved electrodes.•The CAP aptamer connection with CA was used as quenching probes of L-Au NPs.•The CAP combination with quenching probes could restore ECL of L-Au NPs.•The ratio of two ECL intensities was used for specific assay of CAP.A novel ratiometric electrochemiluminescent (R-ECL) aptasensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for antibiotic chloramphenicol (CAP) based on the ratio of working signal to internal reference signal. The SPCE substrate consists of a common Ag/AgCl reference electrode, carbon counter electrode and two spatial-resolved carbon working electrodes (WE1 and WE2). In the system, luminol-gold nanoparticles (L-Au NPs) as working signal tags were modified on WE1, and CdS quantum dots (QDs) were modified on WE2 as internal reference to provide a correction for avoiding the environmental effects. The L-Au NPs at WE1 were functionalized with a CAP aptamer′s DNA complementary (DNA1) and then CAP aptamer (DNA2) that was tagged with chlorogenic acid (CA) as quenchers of L-Au NPs. Upon CAP adding to WE1, the DNA2-CAP complexes were formed due to the highly affinity of CAP towards DNA2. Meanwhile, it could release the CA, which recovered the ECL of L-Au NPs. This ratio of ECL signals for quantification between target probes (at WE1) to internal standard probes (at WE2) could reduce the matrix environmental interference to a certain degree. Moreover, the two probes immobilized on two working electrodes while not one electrode, could also reduce cross-talk interference between each other. Such R-ECL approach offers a selective and sensitive platform and shows a great utility for detection of CAP in the food analysis.
Co-reporter:Haibo Liu, Li Qiao, Ning Gan, Saichai Lin, Yuting Cao, Futao Hu, Jiayu Wang, Yinji Chen
Journal of Chromatography B 2016 Volume 1027() pp:50-56
Publication Date(Web):1 August 2016
DOI:10.1016/j.jchromb.2016.05.022
•CG was used as supporter of MIP to increase adsorption capacity.•MIP coating was simply fabricated based on electro-polymerization luminol.•MIP/CG SBSE coupled with HPLC was applied to determinate three estrogens in milk.Electrochemical polymerization of luminol molecularly imprinted polymer on carboxyl graphene (MIP/CG) was developed as stir bar sorptive extraction (SBSE) coating for selective pre-concentration and specific recognition of bisphenol A (BPA), hexoestrol and diethylstilbestrol in milk samples. Luminol was employed as monomer and BPA as the template to prepare MIP under 0–0.6 V electro-polymerization. Carboxyl graphene was modified on pencil lead as the substrate to increase extraction capacity. The preparation and extraction conditions affecting the extraction efficiency were optimized. Under the optimized conditions, a good linearity of three estrogens was obtained in the range of 4–1000 ng mL−1. The average recoveries at the three spiked levels of the three estrogens ranged from 83.4% to 96.3% with the relative standard deviations (RSD) ≤ 7.1%. The limits of detection were in the range of 0.36–1.09 ng mL−1. The developed method with low cost, high selectivity and good reproducibility can be potentially applied for determining trace estrogens in complex food samples.
Co-reporter:Saichai Lin, Ning Gan, Jiabin Zhang, Li Qiao, Yinji Chen, Yuting Cao
Talanta 2016 Volume 149() pp:266-274
Publication Date(Web):1 March 2016
DOI:10.1016/j.talanta.2015.11.062
•Aptamer-functionalized SBSE coating was applied to selectively detect PCBs.•MOF-5 was used as the substrate of SBSE coating to increase adsorption capacity.•The Apt-SBSE/GC–MS method to determine ng kg−1 PCBs in fish samples.•The MOF-5 was prepared by controlled electro-deposition on the stainless steel wire.In this paper, a novel aptamer-functionalized stir bar sorptive extraction (SBSE) was developed for selective enrichment of the low abundance polychlorinated biphenyls (PCBs) from fish samples. This approach was based on the immobilization of aptamer which could recognize 2,3′,5,5′-tetrachlorobiphenyl (PCB72) and 2′,3′,4′,5,5′-pentachlorobiphenyl (PCB106) on one kind of metal-organic frameworks (Zn4O(BDC)3, MOF-5). MOF-5 as a substrate was prepared by potential-controlled cathodic electrodeposition on stainless steel. This aptamer-functionalized stir bar sorptive extraction (Apt-MOF SBSE) fiber could be facile synthesized in one-step. PCB72 and PCB106 were employed as target analytes for selective extraction by the developed method. The adsorbed targets could be desorbed easily in pH 3.0 100 mM glycine–HCl buffers and then extracted by the methylene chloride. Afterwards, the detection was carried out with gas chromatography–tandem mass spectrometry (GC–MS). The Apt-MOF SBSE pretreatment coupled with GC–MS exhibited high selectivity, good binding capacity, stability and reproducibility for the detection of PCBs. It provided a linear range of 0.02–250 ng mL−1 with a good coefficient of determination (R2=0.9991−0.9996) and the detection limit was 0.003–0.004 ng mL−1. More importantly, the method was successfully utilized for the determination of PCBs in fish samples with good enrichment factor (1930-2304). Therefore, this new SBSE coating opens up the possibility of selective enrichment of a given target PCBs from complex fish samples.
Co-reporter:Yang-Bao Miao, Hong-Xia Ren, Ning Gan, You Zhou, Yuting Cao, Tianhua Li, Yinji Chen
Biosensors and Bioelectronics 2016 Volume 86() pp:477-483
Publication Date(Web):15 December 2016
DOI:10.1016/j.bios.2016.07.007
•A novel ECL assay was successfully developed to detect chloramphenicol.•This strategy was based on EV-Au-SSB nanotracer and Exo-assisted target recycling.•In the EV-Au-SSB, Au and EV can double enhance ECL intensity of CdS NCs.•This method for CAP detection in the fish samples agreed well with those from ELISA.The present study aimed to explore a novel triple-amplification electrochemiluminescence (ECL) assay for detecting of chloramphenicol (CAP). This strategy was based on single-stranded DNA-binding protein (SSB) and horseradish peroxidase (HRP) enzyme-linked polymer (EnVision reagent, EV) labeled on Au nanoparticles (EV–Au–SSB) as nanotracer and exonuclease-assisted target recycling. The composite probes were prepared via immunoreactions between the CdS nanocrystal (CdS NC)-functionalized partial complementary DNA and aptamer (CdSNCs/Apt-ssDNA1) as capture probes, and EV–Au–SSB as nanotracer. When the composite probe solution co-existed with CAP and Exo I, the aptamer on the capture probes preferentially combined with CAP, and then CAP–Apt and nanotracer complex were released into the solution. Subsequently, Exo I in the solution could further digest the CAP–Apt from the 3′-end of the aptamer and release CAP, which could participate in further reaction with the probes. It was worth mentioning that EV contained a large number of HRPs on its dendritic chain. In the EV–Au–SSB, Au could enhance ECL intensity of CdS NCs by surface plasmon resonance. What's more, HRPs on EV could catalyze the reaction of H2O2, which could obviously enhance ECL intensity of CdS NCs. This study demonstrated excellent performance of the triple-amplification ECL assay, which makes this aptasensor system suitable and promising for the practical application of CAP residues in fish samples. Moreover, the assay might provide a promising avenue to develop efficient aptasensors to determine small-molecule harmful substances in environmental monitoring and food safety.
Co-reporter:Zhongdan Yan, Ning Gan, Tianhua Li, Yuting Cao, Yinji Chen
Biosensors and Bioelectronics 2016 Volume 78() pp:51-57
Publication Date(Web):15 April 2016
DOI:10.1016/j.bios.2015.11.019
•A sensitive aptasensor was achieved for multiplex detection of antibiotics.•Different metal ions encoded MHPs were fabricated for signals amplification.•Exonuclease-assisted target recycling were employed for signal amplification.•The dual amplification strategy present a 12-fold-amplified of silica nanotracer.A multiplex electrochemical aptasensor was developed for simultaneous detection of two antibiotics such as chloramphenicol (CAP) and oxytetracycline (OTC), and high-capacity magnetic hollow porous nanotracers coupling exonuclease-assisted target recycling was used to improve sensitivity. The cascade amplification process consists of the exonuclease-assisted target recycling amplification and metal ions encoded magnetic hollow porous nanoparticles (MHPs) to produce voltammetry signals. Upon the specific recognition of aptamers to targets (CAP and OTC), exonuclease I (Exo I) selectively digested the aptamers which were bound with CAP and OTC, then the released CAP and OTC participated new cycling to produce more single DNA, which can act as trigger strands to hybrid with nanotracers to generate further signal amplification. MHPs were used as carriers to load more amounts of metal ions and coupling with Exo I assisted cascade target recycling can amplify the signal for about 12 folds compared with silica based nanotracers. Owing to the dual signal amplification, the linear range between signals and the concentrations of CAP and OTC were obtained in the range of 0.0005–50 ng mL−1. The detection limits of CAP and OTC were 0.15 and 0.10 ng mL−1 (S/N=3) which is more than 2 orders lower than commercial enzyme-linked immunosorbent immunoassay (ELISA) method, respectively. The proposed method was successfully applied to simultaneously detection of CAP and OTC in milk samples. Besides, this aptasensor can be applied to other antibiotics detection by changing the corresponding aptamer. The whole scheme is facile, selective and sensitive enough for antibiotics screening in food safety.
Co-reporter:Meng Chen;Huairong Zhang;Zhongdan Yan;Tianhua Li
Microchimica Acta 2016 Volume 183( Issue 3) pp:1099-1106
Publication Date(Web):2016 March
DOI:10.1007/s00604-015-1695-1
The article describes a multiplex aptamer based voltammetric assay for the food pollutants chloramphenicol (CAP) and polychlorinated biphenyl-72 (PCB72). The method is based on the displacement of a nanotracer (an aptamer-labeled magnetic dendritic probe) by the analytes which cause the release of the corresponding encoded nanotracers. Thiolated aptamers of CAP and PCB72 were first self-assembled on magnetic gold nanoparticles (Fe3O4@Au) as capture probes to concentrate the target analytes CAP and PCB72, respectively. Next, their hybridized complementary strands (cDNA1 or cDNA2) and a dendritic polymerase were linked to quantum dots (CdS or PbS) to form the respective nanotracers. Finally, encoded composite magnetic probes were obtained through hybridization reaction between aptamers and cDNAs. Once CAP and PCB72 are recognized by the composite probes, the nanotracers are released into the supernatant where they can be detected simultaneously by voltammetry of the metal ion markers Cd(II) and Pb(II) at −0.81 and −0.57 V (vs. Ag/AgCl), respectively. The concentration measured for Cd(II) and Pb(II) are directly proportional to the concentrations of CAP and PCB72, respectively, in the range from 0.001 to 100 ng mL−1. The detection limits for CAP and PCB72 are 0.33 and 0.35 pg mL−1, respectively (at an S/N ratio of 3), which is 2 to 3 orders of magnitude lower than the routinely performed and commercially available ELISA. The method is perceived to possess large potential in that it may be applied to other antibiotics by using the appropriate aptamers.
Co-reporter:Li Qiao, Ning Gan, Jiayu Wang, Huiju Gao, Futao Hu, Hongfei Wang, Tianhua Li
Analytica Chimica Acta 2015 Volume 853() pp:342-350
Publication Date(Web):1 January 2015
DOI:10.1016/j.aca.2014.10.041
•A novel 8-electrode array was designed for selective enrichment of trace estrogens.•The coating could be simply fabricated based on electro-polymerization dopamine.•The electrode array exhibited high affinity and selectivity to the targets.•Successful use of the method on the analysis of estrogens in meat samples.A novel 8-electrode array as stir bar was designed for selective extraction of trace level exogenous estrogens from food samples, followed by liquid desorption and HPLC-photodiode array detection. The array consisted of 8 screen-printed electrodes and each electrode was modified with Fe3O4@meso-/macroporous TiO2 microspheres and molecularly imprinted film (m-TiMIF). The fabrication of the imprinted film coating was very simple without organic solvents and chemical grafting. Both bisphenol A (BPA) and diethylstilbestrol (DES) were employed as templates in m-TiMIF fabrication in order to enrich both targets simultaneously. Interestingly, the imprinted stir bar array showed higher extraction capacity and selectivity for BPA and DES than the non-imprinted counterpart. Meanwhile, it exhibited fast adsorption and desorption kinetics due to increased mass transport in the ultra-thin film. Importantly, the m-TiMIF coating was robust enough for at least 20 uses without obvious alteration in extraction performance. The main parameters affecting the extraction efficiency, including stir speeding, sample pH, ionic strength, extraction time, desorption solvent and time, were optimized. Under optimal experimental conditions, the limits of detection (S/N = 3) of the developed method were 0.28 and 0.47 μg L−1 for BPA and DES respectively, with enrichment factors of 32.6 and 52.8-fold. The linear ranges were 3.0–1500 μg L−1 and 4.0–1500 μg L−1 for BPA and DES, respectively. The m-TiMIF-coating conferred better recovery and selectivity, compared with the commercial stir bar coating. The new method was successfully applied to assess BPA and DES in pork and chicken samples with satisfactory recovery.
Co-reporter:De Wang, Tianhua Li, Ning Gan, Huairong Zhang, Nengbing Long, Futao Hu, Yuting Cao, Qianli Jiang, Shan Jiang
Electrochimica Acta 2015 Volume 163() pp:238-245
Publication Date(Web):1 May 2015
DOI:10.1016/j.electacta.2015.02.145
•Electrochemical coding for multiplexed immunoassays was designed for simultaneous detection of biomarkers.•Encoded polymer-nanotags were developed for signal amplification based on Apo nanotags modified on PLL-Au composite.•Apo nanoparticles with a high coding capacity with cadmium and lead ions were used as distinguishable tracer labels.•The polymer-nanotags were simply prepared and environment-friendly by self-assemble technology without coupling agents.A novel sandwich-type electrochemical multiplexed immunoassay was designed for simultaneous determination of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) cancer biomarkers by using bio-based polymer-nanotags as signal probes and dual antibodies labeled magnetic beads as capture probes. This signal probes were prepared by co-immobilizing encoded metallic apoferritin (Cd-Apo and Pb-Apo) and primary antibodies (anti-AFP and anti-CEA) on poly-L-lysine (PLL) via gold nanoparticles (AuNPs). The preparation procedures were through self-assembly technology without using coupling agent. After a sandwich-type immunoreaction, the polymer-nanotags were captured to the surface of Dynabeads. The subsequent electrochemical stripping analysis of the metal components from the nanocomposite provide a means for discriminating dual targets based on the peak potential of Cd and Pb. The currents of Cd and Pb were proportional to the concentration of AFP and CEA, respectively. Experimental results showed the immunoassay enabled the simultaneous determination of AFP and CEA in a single run with dynamic ranges of 0.01-50 ng mL−1. And the detection limits of AFP and CEA were 4 pg mL−1 (S/N = 3), respectively. This proposed multiplexed immunoassay is simple, sensitive and environment-friendly. More importantly, this proposal was employed in real serum samples to detect two tumor markers at the same time. It can be applied for clinical screening of biomarkers.
Co-reporter:Jiabin Zhang, Ning Gan, Si Chen, Muyun Pan, Dazhen Wu, Yuting Cao
Journal of Chromatography A 2015 Volume 1401() pp:24-32
Publication Date(Web):3 July 2015
DOI:10.1016/j.chroma.2015.04.057
•Carboxymethyl-β-cyclodextrin was grafted on the surface Fe3O4@fTiO2 to prepare the adsorbents.•The adsorbents have good selectivity and high adsorption capacity for chlorobenzenes.•Magnetic solid phase extraction was applied for detection of chlorobenzenes in soil samples.A high-performance and selective adsorbent was developed for simultaneous extraction of 6 chlorobenzenes residues in soil samples by using magnetic solid phase extraction (MSPE) combined with automated SPE followed by gas chromatography-mass spectrometry (GC-MS). The adsorbent was synthesized by grafting carboxymethyl-β-cyclodextrin (CM-β-CD) on the surface of porous core–shell magnetic Fe3O4@flower like TiO2 microspheres (Fe3O4@fTiO2-CMCD), used as a carrier. The main factors (adsorbent amount, adsorption time, elution solvent, elution volume, and elution flow rate) affecting the extraction efficiency were investigated in detail. The adsorbent exhibited high loading capacity (25.6 mg g−1 for 1,3-dichlorobenzene). This maybe due to meso-/macroporous TiO2 having high specific surface area; as a carrier of the β-cyclodextrin film, it could obviously increase the number of recognition sites. The newly developed adsorbent also showed good selectivity towards chlorobenzenes based on host–guest interactions between β-cyclodextrin (on adsorbent's surface) and targets, which can minimize complex matrix interference in soil samples. The proposed method was successfully applied for the analysis of environmental soil samples with recovery ranging from 87.3 to 104.3%. All target compounds showed good linearities with correlation coefficients (r) higher than 0.996. The limits of quantitation for the 6 CBs were 0.03–0.09 μg kg−1. These findings confirmed meso-/macroporous structure Fe3O4@fTiO2-CMCD as a highly effective extraction material for use in trace CB analyses in complex soil samples.
Co-reporter:Zhongdan Yan, Ping Xiong, Ning Gan, Jiali He, Nengbing Long, Yuting Cao, Futao Hu, Tianhua Li
Journal of Electroanalytical Chemistry 2015 Volume 736() pp:30-37
Publication Date(Web):1 January 2015
DOI:10.1016/j.jelechem.2014.10.016
•A sandwich-type noncompetitive immunoassay was fabricated to detect DES in milk.•β-CD and antibody in labels can simultaneously recognize DES to raise selectivity.•High sensitivity was obtained by a EV/PtNPs-DES Ab label for signal amplification.•The entire DES detection process requires less than 20 min.A novel sandwich-type noncompetitive electrochemical immunosensor was successfully developed for detecting diethylstilbestrol (DES). First, a novel label (EV/PtNPs-DES Ab) was fabricated by immobilizing numerous platinum nanoparticles (PtNPs) and antibody of DES (DES Ab) on the EnVision™ polymerase chelate (EV). Because DES has two symmetrical phenol groups in the formula, β-cyclodextrin (β-CD) modified on the glassy carbon electrode (GCE) was used to be combined with one phenol group of DES, then forming a host-guest inclusion complex on GCE. Since other structure analogues of DES which has phenol group in food samples could also react with β-CD, thus the signal tag (EV/PtNPs-DES Ab) with DES’s antibodies was used to further conjugated with another phenol group of DES to form a sandwich-type immunocomplex (β-CD/DES/EV/PtNPs-DES Ab) on the sensor. This immunocomplex can trigger significant electro-catalytic current derived from the reduction of H2O2 for quantification of DES. Through two-step recognition of DES by β-cyclodextrin and antibody in labels, a sandwich-type noncompetitive and signal-on immunoassay for DES was achieved. Moreover, the larger amount of PtNPs coupled with HRP on the label could significantly amplify the current and enhance sensitivity. Based on the optimal conditions, this sensor had a good linearity range of 1.00–100 pg mL−1 and a low detection limit of 0.30 pg mL−1 for DES (S/N = 3). The assay was employed for detecting trace DES in milk samples. The results were consistent with that of conventional HPLC method. This implies that this non-competitive immunoassay has potential applications in detection of other small organic molecules in food safety.
Co-reporter:Jiabin Zhang;Muyun Pan;Saichai Lin;Yuting Cao;Dazhen Wu ;Nengbing Long
Journal of Separation Science 2015 Volume 38( Issue 5) pp:871-882
Publication Date(Web):
DOI:10.1002/jssc.201400696
A novel and effective magnetic multiwalled carbon nanotube composite for the separation and enrichment of polychlorinated biphenyls was developed. Fe3O4@SiO2 core–shell structured nanoparticles were first synthesized, then the poly(sodium 4-styrenesulfonate) was laid on its surface to prepare the polyanionic magnetic nanoparticles. The above materials were then grafted with polycationic multiwalled carbon nanotubes, which were modified by polydiallyl dimethyl ammonium chloride through the layer-by-layer self-assembly approach. Its performance was tested by magnetic solid-phase extraction and gas chromatography with mass spectrometry for the determination of six kinds of indicator polychlorinated biphenyls in water samples. Under optimal conditions, the spiked recoveries of several real samples for six kinds of polychlorinated biphenyls (PCB28, PCB52, PCB101, PCB138, PCB153, PCB180) were in the range of 73.4–99.5% with relative standard deviations varying from 1.5 to 8.4%. All target compounds showed good linearities in the tested range with correlation coefficients higher than 0.9993. The limits of quantification for six kinds of indicator polychlorinated biphenyls were between 0.018 and 0.039 ng/mL. The proposed method was successfully applied to analyze polychlorinated biphenyls in real water samples. Satisfactory results were obtained using the effective magnetic absorbent.
Co-reporter:Saichai Lin;Jiabin Zhang;Xidong Chen;Yuting Cao;Tianhua Li
Journal of Molecular Recognition 2015 Volume 28( Issue 6) pp:359-368
Publication Date(Web):
DOI:10.1002/jmr.2450
The novel reductive graphene oxide-based magnetic molecularly imprinted poly(ethylene-co-vinyl alcohol) polymers (rGO@m-MIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs) in fish samples. rGO@m-MIPs was prepared by surface molecular imprinting technique. Besides, Fe3O4 nanoparticles (NPs) were employed as magnetic supporters, and rGO@Fe3O4 was in situ synthesis. Different from functional monomer and cross-linker in traditional molecularly imprinted polymer, here, 3,4-dichlorobenzidine was employed as dummy molecular and poly(ethylene-co-vinyl alcohol) was adopted as the imprinted polymers. After morphology and inner structure of the magnetic adsorbent were characterized, the adsorbent was employed for disperse solid phase extraction toward PCBs and exhibited great selectivity and high adsorption efficiency. This material was verified by determination of PCBs in fish samples combined with gas chromatography-mass spectrometry (GC-MS) method. According to the detection, the low detection limits (LODs) of PCBs were 0.0035–0.0070 µg l−1 and spiked recoveries ranged between 79.90 and 94.23%. The prepared adsorbent can be renewable for at least 16 times and expected to be a new material for the enrichment and determination of PCBs from contaminated fish samples. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Huiju Gao, Ning Gan, Daodong Pan, Yinji Chen, Tianhua Li, Yuting Cao and Tian Fu
Analytical Methods 2015 vol. 7(Issue 16) pp:6528-6536
Publication Date(Web):02 Jul 2015
DOI:10.1039/C5AY01379H
A novel colorimetric aptasensor was developed for sensitive and selective determination of chloramphenicol (CAP) based on gold nanoparticles (AuNPs) labeled with Power Vision (PV) and magnetic separation. PV, with a high enzyme-to-antibody ratio, is composed of a compact enzyme-linker antibody conjunction. In this assay, an aptamer of CAP was immobilized on Fe3O4@Au magnetic nanoparticles as a capture probe (AuMNPs–Apt) to concentrate target CAP. The complementary DNA (cDNA) and PV were both labeled on AuNPs to form a nano-peroxidase polymer as a signal tag (cDNA–AuNPs–PV). And the special tags could hybridize with the aptamer and cDNA to form AuMNP–Apt/cDNA–AuNP–PV conjugates. In the presence of CAP, the aptamer preferentially bound to CAP and caused the dissociation of some cDNA–AuNPs–PV on the conjugates with magnetic separation. PV, carried on signal tags, could greatly catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) leading to color development, which could be quantified by Ultraviolet-visible (UV-vis) spectroscopy. A linear response to CAP concentration in the range of 0.05–200 ng mL−1 was obtained by this proposed method, with a low detection limit down to 0.02 ng mL−1. Besides, this assay was successfully employed to analyze CAP in fish and pork samples, whose results were consistent with those of the conventional enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:De Wang, Ning Gan, Huairong Zhang, Tianhua Li, Li Qiao, Yuting Cao, Xiurong Su, Shan Jiang
Biosensors and Bioelectronics 2015 Volume 65() pp:78-82
Publication Date(Web):15 March 2015
DOI:10.1016/j.bios.2014.09.085
•A signal amplification strategy was constructed for simultaneous detecting AFP and CEA based on graphene–Au signal tags.•Recombinant apoferritin nanoparticles with higher binding capability towards metal ions were used as distinguishable trace labels.•A dual-template magnetic molecularly imprinted polymers were utilized as capture probes for specific recognition with target analytes in real serum samples.A novel electrochemical multiplexed immunoassay was designed for simultaneous determination of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) using recombinant apoferritin-encoded metallic nanoparticles (rApo-M) as labels and dual-template magnetic molecularly imprinted polymers (MMIPs) as capture probes. The labels were prepared by loading recombinant apoferritin (r-Apo) and separately immobilize primary antibodies (anti-AFP and anti-CEA) via Au nanoparticles of in site growth on graphene (G). The capture probes were synthesized by self-polymerization of dopamine (DA) on the Fe3O4 nanoparticles (Fe3O4 NPs) and using AFP and CEA as the template proteins, which were used to enrich the targets simultaneously. After a sandwich-type immunoreaction, the labels were captured to the surface of MMIPs. The subsequent electrochemical stripping analysis of the metal components from the immunocomplex provide a means for quantification of targets based on the peak currents of Cd and Pb. Experimental results showed the immunoassay enabled the simultaneous determination of AFP and CEA in a single run with wide dynamic ranges of 0.001–5 ng mL−1. And the detection limits of AFP and CEA were 0.3 and 0.35 pg mL−1 (S/N=3), respectively. These results suggested that the proposed multiplexed immunoassay would be applied for clinical screening of other biomarkers.
Co-reporter:Zhongdan Yan, Ning Gan, De Wang, Yuting Cao, Meng Chen, Tianhua Li, Yinji Chen
Biosensors and Bioelectronics 2015 Volume 74() pp:718-724
Publication Date(Web):15 December 2015
DOI:10.1016/j.bios.2015.07.024
•A “signal-on’’ aptasensor for simultaneous detection of CAP and PCB72 was built.•Nanospherical branched PEI brushes as signal loader for signal amplification.•The detection was simplified by one-step competitive-type displacement reaction.A “signal-on’’ aptasensor was developed for simultaneous detection of chloramphenicols (CAP) and polychlorinated biphenyl-72 (PCB72) with a novel multi-metal ions encoded nanospherical brushes as nanotracers. To construct the assay, the respective aptamer of CAP and PCB72 labeled magnetic gold nanoparticles as capture probes (aptamer-MGPs), and their complementary single strand DNA (s-DNA) encoded metal ions (Cd2+ and Pb2+) on nanospherical branched polyethylene imine brushes as tracers (s-DNA-MSPEIs), were simultaneously synthesized. After that, the capture probe and tracers were connected through a hybridization reaction between s-DNA and aptamers. In the presence of CAP and PCB72, the analytes could react with the aptamers on capture probes and release the tracers into supernatant after magnetic separation. The released tracers with metal ions (Cd2+ and Pb2+) could be simultaneously detected through the square wave voltammetry (SWV) without acid dissolution, which can switch the signals of the biosensor to “on’’ state. Under optimal conditions, the assay could detect CAP and PCB72 as low as 0.3 pg mL−1 with the dynamitic range from 0.001 to 100 ng mL−1 and exhibited excellent selectivity. More importantly, the strategy can be extended easily to other targets after changing the corresponding aptamers and other metal ions tracers, which provides a promising and facile approach in multiplex detection of ultra-trace level of pollutants in food safety without more complex separation and washing steps.
Co-reporter:Zhongdan Yan, Ning Gan, Huairong Zhang, De Wang, Li Qiao, Yuting Cao, Tianhua Li, Futao Hu
Biosensors and Bioelectronics 2015 Volume 71() pp:207-213
Publication Date(Web):15 September 2015
DOI:10.1016/j.bios.2015.04.010
•A sensitive sandwich-hybridization assay for simultaneous detection of multiple DNA targets.•Different quantum dots-PowerVisionTM polymer nanotracers were used for signal amplification.•The immunoassay was successfully employed in detection of HIV and Tuberculosis DNA at the magnitude of fM.A novel sandwich-hybridization assay for simultaneous electrochemical detection of multiple DNA targets related to human immune deficiency virus (HIV) and tuberculosis (TB) was developed based on the different quantum dots-PowerVisionTM polymer nanotracers. The polymer nanotracers were respectively fabricated by immobilizing SH-labeled oligonucleotides (s-HIV or s-TB), which can partially hybrid with virus DNA (HIV or TB), on gold nanoparticles (Au NPs) and then modified with PowerVisionTM (PV) polymer-encapsulated quantum dots (CdS or PbS) as signal tags. PV is a dendrimer enzyme linked polymer, which can immobilize abundant QDs to amplify the stripping voltammetry signals from the metal ions (Pb or Cd). The capture probes were prepared through the immobilization of SH-labeled oligonucleotides, which can complementary with HIV and TB DNA, on the magnetic Fe3O4@Au (GMPs) beads. After sandwich-hybridization, the polymer nanotracers together with HIV and TB DNA targets were simultaneously introduced onto the surface of GMPs. Then the two encoding metal ions (Cd2+ and Pb2+) were used to differentiate two viruses DNA due to the different subsequent anodic stripping voltammetric peaks at −0.84 V (Cd) and −0.61 V (Pb). Because of the excellent signal amplification of the polymer nanotracers and the great specificity of DNA targets, this assay could detect targets DNA as low as 0.2 femtomolar and exhibited excellent selectivity with the dynamitic range from 0.5 fM to 500 pM. Those results demonstrated that this electrochemical coding assay has great potential in applications for screening more viruses DNA while changing the probes.
Co-reporter:Xiaobin Feng, Ning Gan, Huairong Zhang, Qing Yan, Tianhua Li, Yuting Cao, Futao Hu, Hongwei Yu, Qianli Jiang
Biosensors and Bioelectronics 2015 Volume 74() pp:587-593
Publication Date(Web):15 December 2015
DOI:10.1016/j.bios.2015.06.048
•A novel “dual-potential” ECL aptasensor array based on a homemade screen-printed carbon electrode was designed.•The MG aptamer connect with Cy5 was employed as quenching probes of CdS QDs.•The CAP aptamer connect with CA was used as quenching probes of L-Au NPs.•The MG and CAP combination with corresponding quenching probes could restore cathode ECL of CdS QDs and anode ECL of L-Au NPs simultaneously.•The CdS QDs and L-Au NPs can display high signal intensity at different potentials.A novel type of “dual-potential” electrochemiluminescence (ECL) aptasensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for simultaneous detection of malachite green (MG) and chloramphenicol (CAP) in one single assay. The SPCE substrate consisted of a common Ag/AgCl reference electrode, carbon counter electrode and two carbon working electrodes (WE1 and WE2). In the system, CdS quantum dots (QDs) were modified on WE1 as cathode ECL emitters and luminol-gold nanoparticles (L-Au NPs) were modified on WE2 as anode ECL emitters. Then the MG aptamer complementary strand (MG cDNA) and CAP aptamer complementary strand (CAP cDNA) were attached on CdS QDs and L-Au NPs, respectively. The cDNA would hybridize with corresponding aptamer that was respectively tagged with cyanine dye (Cy5) (as quenchers of CdS QDs) and chlorogenic acid (CA) (as quenchers of l-Au NPs) using poly(ethylenimine) (PEI) as a bridging agent. PEI could lead to a large number of quenchers on the aptamer, which increased the quenching efficiency. Upon MG and CAP adding, the targets could induce strand release due to the highly affinity of analytes toward aptamers. Meanwhile, it could release the Cy5 and CA, which recovered cathode ECL of CdS QDs and anode ECL of L-Au NPs simultaneously. This “dual-potential” ECL strategy could be used to detect MG and CAP with the linear ranges of 0.1–100 nM and 0.2–150 nM, with detection limits of 0.03 nM and 0.07 nM (at 3sB), respectively. More importantly, this designed method was successfully applied to determine MG and CAP in real fish samples and held great potential in the food analysis.
Co-reporter:Xiaobin Feng, Ning Gan, Jing Zhou, Tianhua Li, Yuting Cao, Futao Hu, Hongwei Yu, Qianli Jiang
Electrochimica Acta 2014 Volume 139() pp:127-136
Publication Date(Web):1 September 2014
DOI:10.1016/j.electacta.2014.07.008
•A dual-template MIPs modified electrochemiluminescence immunosensor array was fabricated.•The molecular imprinted films was employed instead of expensive antibody as capture probe.•A novel Ru(bpy)32+-Silica@Poly-L-lysine-Au nanocomposites were employed to connect with antibody as labels.•The labels can dual amplify the signal and display high ECL intensity.•The sensor can near-simultaneously detect two tumor markers in pg mL−1 and U mL−1 order of magnitude in serums.A novel electrochemiluminescence (ECL) immunosensor array was fabricated on a screen-printed electrode (SPE) to perform multiplexed immunoassay of tumor markers (TMs), such as carcinoembryonic antigen (CEA) and carbohydrate antigen-199 (CA199). The SPE substrate consisted of a common Ag/AgCl reference electrode, a common carbon counter electrode and two gold nanoparticles modified carbon working electrodes. Firstly, dopamine (DA) as the functional monomer along with the corresponding TMs (CEA or CA199) as template molecules was electro-polymerized on the surface of different working electrodes. Then, the dual-template molecularly imprinted polydopamine (MIP-PDA) film was formed as the capture probe to recognize CEA and CA199. Secondly, a novel label was fabricated by conjugating the antibodies of TMs with Ru(bpy)32+-Silica@Poly-L-lysine-Au (Ru-Si@PLL-Au) nanocomposites, in which gold colloids (Au NPs) were doped on the surface of Ru-Silica (Ru(bpy)32+-doped Silica) using poly-L-lysine (PLL) as a bridging agent. PLL was also employed as a co-reactant of the luminophore. Based on a sandwich-type immunoassay, the MIP-PDA film, the corresponding antigen and labels were conjugated to produce the immunocomplex. The signals from the ECL immunosensor array were near-simultaneously detected by a photomultiplier tube (PMT) using a homemade single-pore-two-throw switch, which could avoid crosstalk between adjacent working electrodes. The obtained concentrations were 0.05-100 pg mL−1 for CEA and 0.03-80 U L−1 for CA199, with detection limits of 0.02 pg mL−1 and 0.01 U L−1, respectively. This novel ECL strategy provides a simple, economical, fast and sensitive approach for multiplexed immunoassay of CEA and CA199, and has significant potential for protein detection in a clinical laboratory setting.
Co-reporter:Hangzhen Lan, Ning Gan, Daodong Pan, Futao Hu, Tianhua Li, Nengbing Long, Li Qiao
Journal of Chromatography A 2014 Volume 1331() pp:10-18
Publication Date(Web):28 February 2014
DOI:10.1016/j.chroma.2014.01.016
•Characterization of magnetic molecularly imprinted polymer (MMIP).•Developments and evaluation of MMIP as a stationary phase for automated SPME system.•MMIP coatings displayed excellent extraction performance for four estrogens.•The coatings demonstrated extraction capacity, reusability and reproducibility.A new automated solid-phase micro extraction (SPME) sampling method was developed for quantitative enrichment of estrogens (ES) from milk powder, using magnetic molecularly imprinted polymer (MMIP) as fiber coating. The method (MMIP-SPME) was built with several electromagnetic stainless steel fibers, placed in parallel for simultaneously extraction. The MMIP was synthesized using core–shell Fe3O4@SiO2 nanoparticles (NPs) as magnetic support. Estradiol (E2) was employed as the template molecule, acrylamide (AA) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. MMIP can be easily absorbed or desorbed from fibers when the current is turned on or off, creating magnetism. Compared to traditional MIP-SPME, the prepared procedure of MMIP-SPME is time-saving and organic solvent-free. The proposed device significantly improved the efficiency of separation and enrichment of estrogens from complex matrices thereby and facilitating the pretreatment steps by electromagnetically controlled extraction fibers to achieve full automation. Several experimental parameters were studied, including extraction and desorption kinetics, solution pH, desorption solution, ratio, and shuttle rate. The newly developed MMIP-SPME showed good sensitivity and high binding capacity, fast adsorption kinetics and desorption kinetics for estrone (E1), estradiol (E2), estriol (E3) and diethylstilbestrol (DES) under optimized conditions. The detection limits for the four estrogens were 1.5–5.5 ng g−1 with excellent reproducibility (RSD values less than 7.1%) when milk powder samples spiked with analytes at 20, 100 and 250 ng g−1 were studied.
Co-reporter:Jiabin Zhang, Muyun Pan, Ning Gan, Yuting Cao, Dazhen Wu
Journal of Chromatography A 2014 Volume 1364() pp:36-44
Publication Date(Web):17 October 2014
DOI:10.1016/j.chroma.2014.08.076
•A clean-up absorbent was fabricated to eliminate the matrix interference in soils during the detecton of PCBs.•The magneitic β-CD grafted absorbent has stronger absorption towards DDT, DDE, and DDD than highly chlorinated PCBs.•A simple and rapid analytical method for highly chlorinated PCBs in soil samples by dSPE–GC–MS was developed.In this study, we developed a magnetically multifunctional purifying material for efficient removal of matrix interferences, especially certain organochlorine pesticide (DDT, DDE, and DDD), during the determination of toxic highly chlorinated polychlorinated biphenyls (PCBs) at trace levels in soil samples. The multifunctional adsorbent (CMCD-NH2-MNPs) was prepared by grafting carboxymethyl-β-cyclodextrin on the surface of amino-functionalized magnetite (Fe3O4) nanoparticles. CMCD-NH2-MNPs has stronger host–guest complexation with DDT, DDE, and DDD, but the same adsorbent shows weaker adsorption ability toward highly chlorinated PCBs (from tetra- to octa-chlorinated PCBs) owing to their steric hindrance effect. Based on this principle, a simple and rapid gas chromatography–mass spectrometry (GC–MS) method was developed for six indicator PCBs (PCB28, PCB52, PCB101, PCB138, PCB153, and PCB180) in soil. Comparative studies were conducted to determine the clean-up efficiency of the following three techniques: (i) Oasis-HLB, (ii) multi-layer silica column, and (iii) dSPE employing CMCD-NH2-MNPs. The results indicate that CMCD-NH2-MNPs as the purification material can easily and effectively remove DDT, DDE, and DDD in soil samples within a short duration of time. The recoveries for highly chlorinated PCBs were in the range of 85.4–102.2%, with RSDs varying between1.0 and 6.5%. The proposed method was verified as one of the most effective clean-up procedures for the analysis of highly chlorinated PCBs in real soil samples
Co-reporter:Hangzhen Lan, Ning Gan, Daodong Pan, Futao Hu, Tianhua Li, Nengbing Long, Haoyu Shen, Yinjie Feng
Journal of Chromatography A 2014 Volume 1365() pp:35-44
Publication Date(Web):24 October 2014
DOI:10.1016/j.chroma.2014.08.096
•A porous Fe3O4@ZIF-8 was employed as carrier for fabricating a novel magnetic MIP coating on SPME.•The new MIP coating has higher extraction capacity and better selectivity than Fe3O4@SiO2@MIP.•The coating can be easily immobilized and regenerated on SPME fiber using electromagnetic field.•The method has satisfactory LODs, reusability and rapid sample preparation time of 62.5 s/sample.A high-performance magnetic molecularly imprinted polymer (MIP) coating using zeolite imidazolate framework-8 coated magnetic iron oxide (Fe3O4@ZIF-8) as a carrier was developed for simultaneous automated solid phase microextraction of four estrogens in 24 food samples. The coating material, abbreviated as MZMIP, was synthesized through time-efficient layer-by-layer assembling of ZIF-8 and MIP film on Fe3O4 particles. It was characterized and automatically coated on the surface of SPME fibers by electromagnetic bonding. The extraction performance, reusability, repeatability, and validity of the MZMIP–SPME system was evaluated for high-throughput analysis of estrone (E1), estradiol (E2), estriol (E3), and ethinylestradiol (EE2). Various factors affecting the quality of MZMIP coating were optimized. Compared with traditional magnetic MIP coating based on Fe3O4@SiO2 carrier, the MZMIP coating exhibited high extraction capacity and quick adsorption and desorption kinetics to E1, E2, E3, and EE2 owing to the larger amount of imprinting sites in MZMIP. Under optimum conditions, the proposed system requires only 25 min for pretreatment of all 24 samples (62.5 s per sample). The limits of detection and quantitation of the proposed automated system for analysis were found to range from 0.4 to 1.7 and 1.1 to 6.2 ng g−1, respectively. During analysis of spiked fish and pork, the new coating showed better recovery and selectivity compared with Fe3O4@SiO2@MIP (MMIP) and commercially available SPME. The results indicated that the MZMIP coating could be effectively employed for pretreatment of ultra-trace level of estrogens in food.
Co-reporter:Xiaowen Du;Saichai Lin;Xidong Chen;Yuting Cao;Tianhua Li;Pan Zhan
Journal of Separation Science 2014 Volume 37( Issue 13) pp:1591-1600
Publication Date(Web):
DOI:10.1002/jssc.201400146
Novel multi-walled carbon nanotube modified dummy-template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core–shell Fe3O4@SiO2 nanoparticles were employed as magnetic support. 3,4-Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross-linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo-second-order kinetic equation and also exhibited a three-stage intra-particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid-phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028–0.0068 μg/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods.
Co-reporter:Juan Hu, Shaojie Huang, Xiao Huang, Zhuang Kang, Ning Gan
Microporous and Mesoporous Materials 2014 Volume 197() pp:180-184
Publication Date(Web):October 2014
DOI:10.1016/j.micromeso.2014.06.014
•Novel superficially mesoporous Fe3O4@SiO2 core–shell microspheres are synthesized.•The magnetic particles possess IgG binding capacity of 51 mg/g.•Pore enlargement is important for binding of macromolecules such as IgG.Superficially mesoporous Fe3O4@SiO2 core shell microspheres have been synthesized by complex multi-step reactions. The microspheres show three-layered structure: a magnetic core encapsulated by a layer of dense silica and another layer of mesoporous silica. These Fe3O4@SiO2@mesoporous SiO2 microspheres (FSMM) are around 50–100 nm. The outer porous shell can provide much larger surface area than traditional nonporous Fe3O4@SiO2 core shell particles, which is beneficial for enrichment and purification applications. The presence of the superparamagnetic core allows the particles to be isolated and recycled easily by external magnetic field. The pore size of the mesoporous layer of FSMM is further enlarged (E-FSMM) by hydrothermal treatment. The surface of FSMM and E-FSMM are modified with protein G for enrichment and separation of Immunoglobulin G (IgG). FSMM particles exhibit IgG binding capacity of 41 mg/g, while the binding capacity of E-FSMM is as high as 51 mg/g due to the larger pore size facilitating protein binding.Graphical abstract
Co-reporter:Tian-Hua LI, Ning GAN, Da-Zhen WU, Hai-Juan JIN, Yu-Ting CAO, Qian-Li JIANG
Chinese Journal of Analytical Chemistry 2014 Volume 42(Issue 6) pp:817-823
Publication Date(Web):June 2014
DOI:10.1016/S1872-2040(14)60743-X
An ultrasensitive immunoassay was developed on the basis of As3+ and Hg2+ labeled SiO2@Au nanoparticles (NPs) probe and hydride generation-atomic fluorescence spectrometry (HG-AFS) for the detection of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9). Firstly, amino SiO2@Au NPs were synthesized for selective absorption of As3+ and Hg2 to form As(Hg)-SiO2@Au NPs signal tags, respectively. Subsequently, the prepared probes were labeled on the secondary antibody (Ab2) of CEA and CA 19-9, respectively. Based on the sandwich immunoassay scheme, corresponding Ab1, antigen and Ab2 modified with probes, were conjugated to form the immunocomplex on the bottom of 96-well plate at room temperature. After the immunocomplex were dissolved in an alkali solution, As3+ and Hg2+ were released into the solution and detected by HG-AFS, the atomic fluorescence intensity of As3+ and Hg2+ were proportional with logarithms of CEA and CA 19-9 concentration, then indirect quantitative analysis of CEA and CA 19-9 was realized. This assay was based on the determination of the concentration of As3+ and Hg2+ by HG-AFS for quantization of the corresponding CEA and CA 19-9 antigen. The assay showed a wide linear range of 0.001–100.0 µg L−1 for CEA and 0.01–80 U mL−1 for CA 19-9, with the detection limit of 0.5 ng L−1 and 0.005 U mL−1, respectively. This method was used in the determination of real serum samples, and the results were consistent with that from ELISA. This assay showed three orders of magnitude of sensitivity higher than that of ELISA, which provided promising simultaneous multianalyte immunoassays (SMIAs) in the early diagnosis of pancreatic cancer.As3+ labeled SiO2@Au NPs and Hg2+ labeled SiO2@Au NPs were employed for simultaneous multianalyte immunoassay of CEA and CA 19-9 by HG-AFS. The sensitivity of the method was three orders of magnitude higher than that of ELISA.
Co-reporter:Jing Zhou, Ning Gan, Tianhua Li, Futao Hu, Xing Li, Lihong Wang, Lei Zheng
Biosensors and Bioelectronics 2014 Volume 54() pp:199-206
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.10.044
•A rapid and cost-effective sandwich electrochemiluminescence (ECL) immunosensor was fabricated using magnetic molecularly imprinted polymers (MMIPs) as capture probes.•Using MMIPs as capture probes to construct ECL immunosensor could largely lower the cost and improve the stability.•MMIPs could simplify the preparation and provide regenerate steps for the sensor.•MMIPs could enrich ultratrace antibodies and thus achieve ultrasensitive assay.•A new immunoassay for protein detection was created.In this report, a rapid and cost-effective sandwich electrochemiluminescence (ECL) immunosensor was constructed for the ultrasensitive detection of human immunodeficiency virus type 1 antibody (anti-HIV-1) using magnetic molecularly imprinted polymers (MMIPs) as capture probes by combining surface and epitope imprinting techniques and antigen conjugated with horseradish peroxidase (HRP-HIV-1) as labels. First, 3-aminobenzeneboronic acid (APBA) was used as the functional monomer and cross-linking reagent, which was polymerized on the surface of silicate-coated magnetic iron oxide nanoparticles (Fe3O4@SiO2 NPs) in the presence of human immunoglobulin G (HIgG), as the template exhibiting the same Fc region but different Fab region to anti-HIV-1 after the addition of the initiator, ammonium persulfate. This process resulted in grafting a hydrophilic molecularly imprinted polymer (MIP) film on the Fe3O4@SiO2 NPs. Thus, MMIPs, which could be reused after eluting the template, were used to recognize and enrich ultra-trace levels of anti-HIV-1. Subsequently, a novel sandwich ECL immunosensor was formed through the immunoreaction between MMIPs conjugated with varied concentrations of anti-HIV-1 and HRP-HIV-1. By the catalysis of HRP immobilized onto HRP-HIV-1 on the ECL system of Luminol-H2O2, a linear response range of the anti-HIV-1 dilution ratio (standard positive serum) was achieved from 1:20,000 to 1:50, with a detection limit of 1:60,000 (S/N=3). The developed method provides a low-cost, simple, and sensitive way for the early diagnosis of HIV infected patients.
Co-reporter:De Wang, Ning Gan, Jing Zhou, Ping Xiong, Yuting Cao, Tianhua Li, Daodong Pan, Shan Jiang
Sensors and Actuators B: Chemical 2014 197() pp: 244-253
Publication Date(Web):
DOI:10.1016/j.snb.2014.03.011
Co-reporter:Pan ZHAN, Xiao-Wen DU, Ning GAN, Sai-Chai LIN, Tian-Hua LI, Yu-Ting CAO, Wei-Guo SANG
Chinese Journal of Analytical Chemistry 2013 Volume 41(Issue 6) pp:828-834
Publication Date(Web):June 2013
DOI:10.1016/S1872-2040(13)60662-3
Co-reporter:Shanshan Zhu, Futao Hu, Ting Yang, Ning Gan, Daodong Pan, Yuting Cao, Dazhen Wu
Journal of Chromatography B 2013 Volumes 921–922() pp:21-26
Publication Date(Web):15 March 2013
DOI:10.1016/j.jchromb.2013.01.022
Analysis of tributyltin chloride (TBT) in environmental samples, such as seawater, is important in order to evaluate the TBT contamination and accumulation in the trophic chain. The environmental impact of organotin compounds has been a particular focus of analytical studies. The present study reports the use of molecular imprinting technology coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS) to determine trace amounts of TBT in seawater and seafood (mussel tissue samples). The imprinted polymer was synthesized by a non-covalent free-radical approach using acrylamide (AM) as a monomer and TBT as a template molecule in acetonitrile solvent (polymerization media). The imprinted polymer synthesized by this approach exhibited good adsorptive capacity and allowed specific retention of TBT. Recoveries of TBT in seawater samples spiked with different TBT concentrations ranged from 67.2% to 81.1% with peak area precision (RSD) < 3.7%, and recoveries of TBT in mussel tissue samples ranged from 75.0% to 94.2% with RSD < 4.8%.Highlights► Imprinted polymer with acrylamide as monomer for adsorbing tributyltin chloride. ► High retention capacity and selectivity for this adsorbent. ► Developing a new analysis approach by coupling this polymer to LC–MS/MS.
Co-reporter:Jing Zhou, Ning Gan, Futao Hu, Tianhua Li, Hankun Zhou, Xing Li, Lei Zheng
Sensors and Actuators B: Chemical 2013 Volume 186() pp:300-307
Publication Date(Web):September 2013
DOI:10.1016/j.snb.2013.06.021
A single antibody sandwich electrochemiluminescence (ECL) immunosensor for ultratrace detection of protein was developed using magnetic molecularly imprinted polymers (MMIPs) as an alternative to the first antibody as capture probes and antibodies labeled with Ru-silica (Ru(bpy)32+-doped silica) doped Au (Ru@SiO2@Au) nanocomposites as labels. Using MMIPs as capture probes will aid mass production, greatly reduce costs and avoid the loss of bioactivity associated with the use of conventional antibodies. Moreover, MMIPs can be easily immobilized on and washed off simply by adding or removing a magnet on the electrode, which will greatly simplify the preparation and allow regeneration of the sensor. Lastly, MMIPs can enrich ultratrace levels of antigens from sample solutions to produce more immunocomplex than the conventional capture probe, thus providing an ultrasensitive assay. The logarithm of ΔECL intensity depended linearly on the logarithm of the hemoglobin (Hb) concentration in the range from 0.1 to 4 × 104 pg mL−1 with a detection limit of 0.023 pg mL−1. This approach offers obvious advantages of low cost, high sensitivity and enhanced stability compared with other immunosensors, and therefore offers significant potential for protein detection in a clinical laboratory setting.
Co-reporter:Jing Zhou, Ning Gan, Tianhua Li, Hankun Zhou, Xing Li, Yuting Cao, Lihong Wang, Weiguo Sang, Futao Hu
Sensors and Actuators B: Chemical 2013 178() pp: 494-500
Publication Date(Web):
DOI:10.1016/j.snb.2013.01.013
Co-reporter:Shanshan Zhu;Daodong Pan;Yi Li;Ting Yang;Futao Hu
Microchimica Acta 2013 Volume 180( Issue 7-8) pp:545-553
Publication Date(Web):2013 June
DOI:10.1007/s00604-013-0962-2
Co-reporter:Hankun Zhou, Ning Gan, Tianhua Li, Yuting Cao, Saolin Zeng, Lei Zheng, Zhiyong Guo
Analytica Chimica Acta 2012 Volume 746() pp:107-113
Publication Date(Web):9 October 2012
DOI:10.1016/j.aca.2012.08.036
A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of α-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe3O4-Au nanoparticles, which was first employed to capture AFP antigens to form Fe3O4-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe3O4-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe3O4-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL−1 with a detection limit of 0.2 pg mL−1. The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the amplification of the signal tag, the immunosensor is highly sensitive, which can offer great promise for rapid, simple, selective and cost-effective detection of effective biomonitoring for clinical application.Graphical abstractHighlights► Sandwich immunoreaction, testing a large number of samples simultaneously. ► The magnetic separation and enrichment by Fe3O4-Au magnetic nano probes. ► The amplification of detection signal by CdS-Au composite nanoparticles labeled anti-AFP. ► Almost no background signal, which greatly improve the sensitivity of detection.
Co-reporter:Yuan-Zhao WU, Ning GAN, Fu-Tao HU, Tian-Hua LI, Yu-Ting CAO, Lei ZHENG
Chinese Journal of Analytical Chemistry 2011 Volume 39(Issue 11) pp:1634-1640
Publication Date(Web):November 2011
DOI:10.1016/S1872-2040(10)60479-3
A new type of one-dimensional magnetic nanoprobe was fabricated based on a DNA chain fixed with numerous Fe3O4 (core)/ZrO2 (shell) nanomagnetic beads (ZMPs) modified with horseradish peroxidase (HRP)-labeled anti-α-fetoprotein secondary antibody (AFPAb2). An electrochemical immunosensor for AFP was developed using the nanoprobe DNA/(ZMPs-HRP-AFPAb2)n and AFP-antibody (AFPAb1)-immobilized glassy carbon electrode (GCE) modified with nanogold. A sandwich-type immunocomplex could be formed between the immobilized AFPAb1 on the GCE, the AFP sample, and the probe DNA/(ZMPs-HRP-AFPAb2)n; moreover, the linked HRP on the probes could catalyze the electrochemical reaction of carbamide peroxide in the presence of hydroquinone. Under optimal conditions, the immunosensor response showed a linear relationship with the AFP concentration in the range 0.01–25 μg L−1, with a detection limit of 4 ng L−1. The immunosensor was used to determine the AFP level in serum samples, and the results were satisfactory. The proposed amperometric immunosensor was sensitive, provided a rapid detection, and was controllable by a magnetic field. This study provides a strategy for the one-dimensional assembly and development of highly sensitive immunosensors.
Co-reporter:Ning GAN, Nai-Xing LUO, Tian-Hua LI, Lei ZHENG, Min-Jun NI
Chinese Journal of Analytical Chemistry 2010 Volume 38(Issue 11) pp:1556-1562
Publication Date(Web):November 2010
DOI:10.1016/S1872-2040(09)60076-1
Co-reporter:Ning GAN, Lu-Yan WANG, Tian-Hua LI, Lei ZHENG, Feng WANG
Chinese Journal of Analytical Chemistry 2009 Volume 37(Issue 8) pp:1125-1130
Publication Date(Web):August 2009
DOI:10.1016/S1872-2040(08)60121-8
A novel amperometric immunosensor is investigated for human immunodeficiency virus (HIV) glycoprotein 160 (gp160) based on nano-Fe3O4 (core)/Au (shell)/chitosan composite film as immobilization matrix. First, the complex [Cu(bpy)2(H2O)]2·(C6H8O4)2(ClO4)4(CuL) was prepared and adsorbed on the surface of glass carbon electrode (GCE), then nano-Fe3O4 (core)/Au (shell)/chitosan composite film was modified on the surface of GCE|CuL, and HIV gp160 antibody was furthermore immobilized on the surface to form one gp160 immunosensor (GCE|CuL/nano-Fe3O4 (core)/Au (shell)/chit/anti gp160). CuL can be used as an electron transfer mediator for catalytic activity detection of H2O2. After the immunosensor is incubated with HIV gp160 solution at 37 °C for 30 min, the electron transfer access of CuL to H2O2 is partly inhibited, which leads to a linear decrease of the catalytic efficiency to H2O2 by the oxidation of immobilized CuL by H2O2 at −300 mV in PBS at pH 7.0. Under the optimal conditions, the linear range of gp160 by the immunosensor is from 1 to 400 ng ml−1, and the detection limit is 0.5 ng ml−1 at three times noise. The immunosensor shows more sensitivity and accuracy than the immunosensor only modified by gp160 antibody coated nano-Au/chitosan film. This method simplifies the detection system without adding electron transfer media to solution and shortens the analytical time with one-step immunoassay, thus it would be valuable for clinical immunoassay for HIV gp160 in serums of patients with AIDs.
Co-reporter:Ning GAN, Tian-Hua LI, Jian-Ping LEI, Lu-Yan WANG, Xin YANG
Chinese Journal of Analytical Chemistry 2008 Volume 36(Issue 9) pp:1167-1171
Publication Date(Web):September 2008
DOI:10.1016/S1872-2040(08)60064-X
An immunosensor based on mercapto succinic acid hydrazide copper (II) (CuL) monolayer modified gold electrode (Au|CuL) was developed for the determination of human immunodeficiency virus p24 antigen in acquired immunodeficiency syndrome patients' serum. CuL displays reductive electrocatalyzation for H2O2 and can be employed as electron transfer media between HRP and electrode. Based on a competition immunoreaction, a differential pulse voltammetric determination method for p24 antigen was established by the peak current increase of the immobilized CuL. The current increase results from the enhanced catalytic current of H2O2 reduction with the help of HRP labeled immunocomplex. The free immunocomplex was produced by competitive binding to the limited amount of HRP labeled p24 antibody (HRP-anti p24) from the p24 in sample solution and immobilized on the bottom of the detective hole. The proposed method needs neither separation nor washing up step, which simplifies the immunoassay procedure and shortens the analytical time. The method provides a new promising platform for diagnosing the AIDs disease.
Co-reporter:Lingying Zhou, Ning Gan, You Zhou, Tianhua Li, Yuting Cao, Yinji Chen
Talanta (15 May 2017) Volume 167() pp:544-549
Publication Date(Web):15 May 2017
DOI:10.1016/j.talanta.2017.02.061
Co-reporter:Qianli Jiang, Denan Zhang, Yuting Cao, Ning Gan
Journal of Electroanalytical Chemistry (15 March 2017) Volume 789() pp:
Publication Date(Web):15 March 2017
DOI:10.1016/j.jelechem.2017.02.020
•A novel MMIPs -QDs-Aptamer conjugated ECL probes were prepared for DES detection.•DES, MMIPs and QDs-aptamer labels can form a sandwich complex specifically.•The ECL sensor can produce signal-on signal and probes are cheap for mass production.An antibody free and signal-on type electrochemiluminescence(ECL) sensor was developed for diethylstilbestrol (DES) detection using magnetic surface magnetic molecular imprinting polymers (MMIPs) - aptamer labeled CdS quantum dots (CdS QDs) conjugated probes. Firstly, the MMIPs were synthesized through employing 4″-hydroxypropiophenone as mimicking template to form imprint sites on the poly-dopamine coating covering core-shell Fe3O4@SiO2 (MMIPs). Secondly, the aptamer which epitope is phenol group of 17β-estradiol (E2), was chosen to label on CdS QDs to form CdS-Apt signal tag and recognize phenol group of DES. When the target, MMIPs and CdS-Apt was incubated together, a sandwich MMIPs-DES-CdS-Apt composite was constructed. It was then adsorbed on the interface of a screen printed carbon electrode (SPCE) by external magnetic field, then emit electrochemical luminescence signal at potential − 1.1 V. The signal intensity was in proportion to the logarithm of DES' concentration from 0.3 to 1.0 × 105 pg ml− 1, with the detection limit (LOD) of 0.1 pg ml− 1 (S/N = 3). Several fish samples were tested by the sensor which showed high selectivity and good recoveries between 80% and 120% with consistent results as that of conventional ELISA. Since there have been no reports of aptamer for DES, we use E2 aptamer to recognize phenol epitope of DES, then MMIPs towards another epitope to form a sandwich complex. Thus a signal-on and sandwich sensor was fabricated. Moreover, no expensive antibody was employed for fabricating the sensor. Its selectivity and sensitivity were higher than the same type of sensor based on sole aptamer or MIPs probe. The assay can be explored to detect other analytes while changing the corresponding aptamer and imprinting template.ECL assay for DES using MMIPs-CdS-Apt conjugated probes.
Co-reporter:
Analytical Methods (2009-Present) 2015 - vol. 7(Issue 16) pp:NaN6536-6536
Publication Date(Web):2015/07/02
DOI:10.1039/C5AY01379H
A novel colorimetric aptasensor was developed for sensitive and selective determination of chloramphenicol (CAP) based on gold nanoparticles (AuNPs) labeled with Power Vision (PV) and magnetic separation. PV, with a high enzyme-to-antibody ratio, is composed of a compact enzyme-linker antibody conjunction. In this assay, an aptamer of CAP was immobilized on Fe3O4@Au magnetic nanoparticles as a capture probe (AuMNPs–Apt) to concentrate target CAP. The complementary DNA (cDNA) and PV were both labeled on AuNPs to form a nano-peroxidase polymer as a signal tag (cDNA–AuNPs–PV). And the special tags could hybridize with the aptamer and cDNA to form AuMNP–Apt/cDNA–AuNP–PV conjugates. In the presence of CAP, the aptamer preferentially bound to CAP and caused the dissociation of some cDNA–AuNPs–PV on the conjugates with magnetic separation. PV, carried on signal tags, could greatly catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) leading to color development, which could be quantified by Ultraviolet-visible (UV-vis) spectroscopy. A linear response to CAP concentration in the range of 0.05–200 ng mL−1 was obtained by this proposed method, with a low detection limit down to 0.02 ng mL−1. Besides, this assay was successfully employed to analyze CAP in fish and pork samples, whose results were consistent with those of the conventional enzyme-linked immunosorbent assay (ELISA) method.
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