Co-reporter:Jinyu Lian;Qiang Liu;Yan Jin
Chemical Communications 2017 vol. 53(Issue 93) pp:12568-12571
Publication Date(Web):2017/11/21
DOI:10.1039/C7CC07424G
The histone–DNA interaction is found to greatly improve the fluorescence intensity and stability of DNA-templated Cu nanoclusters (CuNCs), which would be highly beneficial for the application of CuNCs in biosensing/imaging.
Co-reporter:Mei Liu, Jiao Li, Baoxin Li
Talanta 2017 Volume 175(Volume 175) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.talanta.2017.07.003
•A colorimetric assay for the ultrasensitive determination of thrombin was proposed.•The catalytic ability of PMNT derived from decomposing H2O2 into ·OH radicals.•The catalytic activity of PMNT was closely relevant to the conformation of PMNT.A colorimetric assay for the ultrasensitive determination of thrombin was presented, in which the cationic polythiophene derivative was used as catalyst of the 3,3′,5,5′-tetramethylbenzidine (TMB)–H2O2 reaction and the thrombin-binding aptamer (TBA) was used as inducing polymer's different conformation elements. It was found the cationic polythiophene derivative, poly[3-(3′-N,N,N-triethylamino-1′-propyloxy)-4-methyl-2,5-t-hiophene hydrochloride] (PMNT), can catalyze the oxidation reaction of TMB in the presence of H2O2 to produce a blue color solution. The catalytic activity of PMNT on the TMB–H2O2 reaction was closely relevant to the conformation of PMNT. The absorbance of TMB–H2O2 was distinctly increased in the presence of TBA. With the addition of thrombin, TBA interacted with thrombin to form a G-quadruplex structure. The conformational change weakened the catalytic activity of PMNT and resulted in a decrease in the absorbance. The colorimetric sensor could detect thrombin down to 4 pM with high selectivity against other interfering proteins. This work is not only of importance for a better understanding of the unique properties of cationic polythiophenes derivative but also have great potential for medical diagnostics and therapy for human health.Aptamer biosensor for thrombin detection based on cationic polythiophene derivative with different conformation as peroxidase mimetics.Download high-res image (159KB)Download full-size image
Co-reporter:Jingjing Dong;Jinyu Lian;Yan Jin
Analytical Methods (2009-Present) 2017 vol. 9(Issue 2) pp:276-281
Publication Date(Web):2017/01/05
DOI:10.1039/C6AY02964G
Assay of uracil-DNA glycosylase (UDG) activity is a crucial step for understanding some fundamental biochemical processes. Herein, we developed a simple and fast chemiluminescence (CL) method for the assay of UDG activity. In this method, one dsDNA probe containing fluorescein amidite-labeled G-rich ssDNA was used as a substrate for UDG. The dsDNA probe reacted with 3,4,5-trimethoxylphenylglyoxal to emit strong CL due to guanine-based chemiluminescence resonance energy transfer (CRET). The UDG-catalyzed uracil removal liberated G-rich ssDNA from the dsDNA substrate; then, in the presence of K+, G-rich ssDNA was converted to a G-quadruplex, which gives low CL emission. Therefore, using the CL response of the DNA probe as a signal indicator, UDG activity was determined in a simple process with high specificity, and a detection limit of 0.3 U mL−1 was achieved without any signal amplification. This simple and rapid methodology may have potential application in the UDG-related clinical diagnoses and functional studies.
Co-reporter:Guoxin Song;Fulin Zhou;Chunli Xu
Analyst (1876-Present) 2017 vol. 142(Issue 14) pp:2678-2678
Publication Date(Web):2017/07/10
DOI:10.1039/C7AN90049J
Correction for ‘A universal strategy for visual chiral recognition of α-amino acids with L-tartaric acid-capped gold nanoparticles as colorimetric probes’ by Guoxin Song et al., Analyst, 2016, 141, 1257–1265.
Co-reporter:Hengzhi Zhao, Qiang Liu, Mei Liu, Yan Jin, Baoxin Li
Talanta 2017 Volume 165() pp:653-658
Publication Date(Web):1 April 2017
DOI:10.1016/j.talanta.2017.01.027
•A label-free and sensitive fluorescence assay for T4 PNKP activity is developed.•Commercially available thioflavin T dye is used as signal probe.•The whole assay process can be completed in a single tube.T4 polynucleotide kinase phosphatase (T4 PNKP) is a bifunctional tool enzyme with 5′-kinase and 3′-phosphatase activities. Considering its important roles in the repair of strand breaks, assay of T4 PNKP activity is of great importance. In this work, we proposed a novel label-free sensing strategy for T4 PNKP activity based on G-quadruplexe−thioflavin T fluorescent indicator. In the assay, we used a single stranded oligonucleotide with 3′-phosphoryl and 5′-phosphoryl ends as enzyme substrate. Upon the addition of T4 PNKP, the 3′-PO3 of the substrate was changed to 3′-OH which initiated the polymerization in the presence of terminal deoxynucleotidyl transferase and G-rich dNTP substrates. The resultant elongated DNA can form G-quadruplex in the inducement of K+, resulting in strong fluorescence signal when using thioflavin T as a G-quadruplex−specific light-up fluorescent probe. The detection limit of this method is as low as 0.2 U/mL. Additionally, the inhibition of T4 PNKP activity by the inhibitor heparin is demonstrated. This method is easy and convenient to operate in homogeneous solution, and the whole assay process can be completed in a single tube.A label-free fluorescence assay for T4 PNKP activity is developed using G-quadruplexe−thioflavin T complex as signal indictor.
Co-reporter:Guoxin Song, Fulin Zhou, Chunli Xu and Baoxin Li
Analyst 2016 vol. 141(Issue 4) pp:1257-1265
Publication Date(Web):04 Jan 2016
DOI:10.1039/C5AN02434J
The ability to recognize and quantify the chirality of alpha-amino acids constitutes the basis of many critical areas for specific targeting in drug development and metabolite probing. It is still challenging to conveniently distinguish the enantiomer of amino acids largely due to the lack of a universal and simple strategy. In this work, we report a strategy for the visual recognition of α-amino acids. It is based on the chirality of L-tartaric acid-capped gold nanoparticles (L-TA-capped AuNPs, ca. 13 nm in diameter). All of 19 right-handed α-amino acids can induce a red-to-blue color change of L-TA-capped AuNP solution, whereas all of the left-handed amino acids (except cysteine) cannot. The chiral recognition can be achieved by the naked eye and a simple spectrophotometer. This method does not require complicated chiral modification, and excels through its low-cost, good availability of materials and its simplicity. Another notable feature of this method is its high generality, and this method can discriminate almost all native α-amino acid enantiomers. This versatile method could be potentially used for high-throughput chiral recognition of amino acids.
Co-reporter:Cunwei Liu, Jinyu Lian, Qiang Liu, Chunli Xu and Baoxin Li
Analytical Methods 2016 vol. 8(Issue 29) pp:5794-5800
Publication Date(Web):28 Jun 2016
DOI:10.1039/C6AY01308B
Efficient enantiomer discrimination by a convenient method remains a challenge in biochemical and pharmaceutical fields. Herein we have modified silver nanoparticles (AgNPs) with β-cyclodextrin (β-CD) to obtain a probe for the chiral recognition of aromatic α-amino acids. This assay relies on the distance-dependent optical properties of AgNPs and the difference in inclusion binding strength between the aromatic amino acid enantiomers and the β-CD host. The response of β-CD functionalized-AgNPs to certain chiral aromatic amino acid enantiomers namely D- and L-phenylalanine (Phe), D- and L-tryptophan (Trp), and D- and L-tyrosine (Tyr) in phosphate buffer solutions was studied in detail. In the presence of D-Phe (or L-Trp or L-Tyr), an appreciable yellow-to-red color change of the AgNP solution can be observed, whereas no color change is found in the presence of L-Phe (or D-Trp or D-Tyr). This method can be used to quantitatively determine the percentage of D-Phe in a mixture of D- and L-Phe. The chiral assay described in this work is easily readout with the naked eye or using a cheap UV-vis spectrometer. This method excels by its simplicity, low cost, and good availability of materials.
Co-reporter:Manman Cao, Yan Jin and Baoxin Li
Analytical Methods 2016 vol. 8(Issue 22) pp:4319-4323
Publication Date(Web):09 May 2016
DOI:10.1039/C6AY00900J
Sensitive detection of uracil–DNA glycosylase (UDG) activity is critical for the functional study of UDG and clinical diagnosis. Herein we exploit dsDNA-templated copper nanoclusters (CuNCs) as a fluorescent nano-dye for UDG assay. The UDG-catalyzed uracil removal can liberate ssDNA from the uracil-containing dsDNA substrate, and thus the introduction of Cu2+ and ascorbate cannot form the fluorescent CuNCs due to the lack of the dsDNA templates. By optimizing the number and location of uracil on the DNA strand, a low detection limit of 0.0005 U mL−1 was achieved. The simple and sensitive method may hold potential applications in UDG-related clinical diagnosis and functional research.
Co-reporter:Fulin Zhou and Baoxin Li
Analytical Chemistry 2015 Volume 87(Issue 14) pp:7156
Publication Date(Web):June 25, 2015
DOI:10.1021/acs.analchem.5b00993
Detection of ultralow concentration of specific DNA sequence is a central challenge in the early diagnosis of gene-related disease and biodefense application. Herein, we report a dual-amplification strategy for highly sensitive fluorescence detection of DNA. In this proposed strategy, a dumbbell-shaped DNA probe is designed to integrate target binding, magnetic separation, and signal response. In the presence of specific DNA target, the multifunctional dumbbell probe can initiate exonuclease III (Exo III)-aided target recycling amplification, and, in the meantime, generate a large number of fluorescein (FAM)-encapsulated liposomes. The developed method offers very high sensitivity due to primary amplification via numerous FAM from a liposome and secondary amplification via target recycling amplification. The detection limit of the proposed method can reach 4 aM, which is much lower than that of the Exo III-aided target recycling technique applied for DNA quantification without FAM-encapsulated liposomes amplification. Moreover, the dual-signal amplification process can be completed one-step in this system. Therefore, this method provides a simple, isothermal, and low-cost approach for sensitive detection of DNA and holds a great potential for early diagnosis in gene-related diseases.
Co-reporter:Lin Zhang, Chunli Xu, Guoxin Song and Baoxin Li
RSC Advances 2015 vol. 5(Issue 34) pp:27003-27008
Publication Date(Web):11 Mar 2015
DOI:10.1039/C5RA01271F
A simple protocol to distinguish enantiomers is extremely intriguing and useful. Herein, we report on a method for the visual recognition of 3,4-dihydroxyphenylalanine (Dopa) enantiomers. It is based on the chirality of L-cysteine-capped gold nanoparticles (L-Cys-capped AuNPs) that can be used as a chiral selector for L- and D- forms of Dopa. On addition of L-Dopa to a solution of the L-Cys-capped AuNPs, a color change from red to blue can be seen, while no color change is found on addition of D-Dopa. The chiral recognition can be achieved by eye and simple spectrophotometry. Notably, this method does not require complicated chiral modification. The method excels through its low-cost, good availability of materials, and its simplicity.
Co-reporter:Fulin Zhou, Baoxin Li and Jiyuan Ma
RSC Advances 2015 vol. 5(Issue 6) pp:4019-4025
Publication Date(Web):05 Dec 2014
DOI:10.1039/C4RA14467H
Herein, we report a simple and homogenous fluorescence method for ultrasensitive DNA detection. It is based on rolling circle amplification (RCA) and fluorescence resonance energy transfer (FRET). As an alternative to a molecular beacon (MB), a linear single-labeled DNA probe was used in this RCA-based fluorescence strategy for DNA detection. The performance of linear DNA probes was compared with that of the MB probe in an RCA-based fluorescence strategy. The results showed that the linear DNA probes could effectively avoid the fluorescence quenching between neighboring signal probes, which would significantly improve the sensitivity of the RCA-based fluorescence strategy. This method exhibited a high sensitivity toward target DNA with a detection limit of 0.7 aM, which was about 100-fold lower than that of the RCA-based fluorescence strategy with MB as the signal probe. This method provides a simple, isothermal, and low-cost approach for sensitive detection of DNA and holds great potential for early diagnosis in gene-related diseases.
Co-reporter:Guoxin Song, Chunli Xu, Baoxin Li
Sensors and Actuators B: Chemical 2015 215() pp: 504-509
Publication Date(Web):
DOI:10.1016/j.snb.2015.03.109
Co-reporter:Shan Ren;Fulin Zhou;Chunli Xu
Gold Bulletin 2015 Volume 48( Issue 3-4) pp:147-152
Publication Date(Web):2015 December
DOI:10.1007/s13404-015-0171-3
An operationally simple colorimetric method for measuring glutathione S-transferase (GST) activity was developed using cysteamine-capped gold nanoparticles (AuNPs) in this work. This method was based that GST can catalyze the reaction of 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione (GSH) to produce a conjugate (CDNB-SG). GSH could induce the aggregation of AuNPs, whereas the conjugate could not induce the aggregation of AuNPs. Thus, GST activity can be facilely assayed with the naked eye or a simple colorimetric reader. The convenient and simple colorimetric response of the assay makes them an attractive approach for drug-screening application.
Co-reporter:Min Xu, Baoxin Li
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2015 Volume 151() pp:22-26
Publication Date(Web):5 December 2015
DOI:10.1016/j.saa.2015.06.052
•A label-free and sensitive fluorescence assay for exonuclease activity is developed.•Commercially available SYBR Green I (SG) dye is used as signal probe.•This method has a linear detection range from 1 to 200 U/mL with a detection limit of 0.7 U/mL.A label-free and sensitive fluorescence assay for exonuclease activity is developed using commercially available SYBR Green I (SG) dye as signal probe. A proof-of-concept of this assay has been demonstrated by using exonuclease III (Exo III) as a model enzyme. In this assay, double-stranded DNA (dsDNA) can bind SG, resulting in a strong fluorescence signal of SG. Upon the addition of Exo III, dsDNA would be digested, and SG emits very weak fluorescence. Thus, Exo III activity can be facilely measured with a simple fluorescence reader. This method has a linear detection range from 1 U/mL to 200 U/mL with a detection limit of 0.7 U/mL. This label-free approach is selective, simple, convenient and cost-efficient without any complex DNA sequence design or fluorescence dye label. The method not only provides a platform for monitoring activity and inhibition of exonuclease but also shows great potential in biological process researches, drug discovery, and clinic diagnostics.A label-free and sensitive fluorescence assay for exonuclease activity is developed using commercially available SYBR Green I dye as signal probe.
Co-reporter:Yuan Gao and Baoxin Li
Analytical Chemistry 2014 Volume 86(Issue 17) pp:8881
Publication Date(Web):August 14, 2014
DOI:10.1021/ac5024952
Detection of ultralow concentrations of specific nucleic acid sequences is a central challenge in the early diagnosis of genetic diseases and biodefense applications. Herein, we report a simple and homogeneous chemiluminescence (CL) method for ultrasensitive DNA detection. It is based on the exonuclease III (Exo III)-assisted cascade signal amplification and the catalytic effect of G-quadruplex–hemin DNAzyme on the luminol–H2O2 CL system. A quadruplex-forming DNA probe hybridizes a hairpin DNA probe to construct a duplex DNA probe as recognition element. Upon sensing of target DNA, the recognition of target DNA and the duplex DNA probe triggers the Exo III cleavage process, accompanied by releasing target DNA and generating a new secondary target DNA fragment. The released target DNA and the secondary target DNA are recycled. Simultaneously, numerous quadruplex-forming sequences are liberated and bind hemin to yield G-quadruplex–hemin DNAzyme, which subsequently catalyze the luminol–H2O2 reaction to produce strong CL emission. This method exhibited a high sensitivity toward target DNA with a detection limit of 8 fM, which was about 100 times lower than that of the reported DNAzyme-based colorimetric system for DNA detection with Exo III-assisted cascade signal amplification. This method provides a simple, isothermal, and low-cost approach for sensitive detection of DNA and holds a great potential for early diagnosis in gene-related diseases.
Co-reporter:Lin Zhang, Chunli Xu, Cunwei Liu, Baoxin Li
Analytica Chimica Acta 2014 Volume 809() pp:123-127
Publication Date(Web):27 January 2014
DOI:10.1016/j.aca.2013.11.043
•A low-cost, facile, sensitive method is proposed for visual chiral recognition of enantimers.•The unmodified AuNPs are firstly used as chiral selector for d- and l-Tryptophan.•This work provides a new experimental evidence for intrinsic chirality of AuNPs.A simple protocol to distinguish enantiomers is extremely intriguing and useful. In this study, we propose a low-cost, facile, sensitive method for visual chiral recognition of enantimers. It is based on the inherent chirality of gold nanoparticles (AuNPs), and the unmodified AuNPs are used as chiral selector for d- and l-Tryptophan (Trp). In the presence of d-Trp, an appreciable red-to-blue color change of AuNPs solution can be observed, whereas no color change is found in the presence of l-Trp. The method can be used to detect d-Trp in the range of 0.2–10 μM, and the limit of detection is 0.1 μM. The chiral assay described in this work is easily readout with the naked eye or using a UV-vis spectrometer. Furthermore, the AuNPs can selectively adsorb d-Trp, and simple centrifugation can allow the precipitation of d-Trp with AuNPs and leave a net excess of the other enantiomer in solution, thus resulting in enantioseparation. In this method, AuNPs do not need any labeling or modifying with chiral molecules. The method is more attractive because of its high sensitivity, low cost, ready availability and simple manipulation.Based on the inherent chirality of gold nanoparticles (AuNPs), a low-cost, facile and sensitive method for visual chiral recognition of tryptophan was suggested.
Co-reporter:Yingying Qi, Fu-Rong Xiu, Baoxin Li
Analytical Biochemistry 2014 Volume 449() pp:1-8
Publication Date(Web):15 March 2014
DOI:10.1016/j.ab.2013.12.007
Abstract
The catalytic activity of gold nanoparticles (AuNPs) on a luminol–H2O2 chemiluminescence (CL) system is found to be greatly enhanced after its crosslinking aggregation induced by immunoreaction. Based on this observation, a one-step homogeneous non-stripping CL metalloimmunoassay was designed. In the presence of corresponding antigen (Ag), the immunoreaction caused the aggregation of antibody (Ab)-modified AuNPs, and these crosslinking aggregated AuNPs could catalyze luminol–H2O2 CL reaction to produce a much stronger CL signal than dispersed Ab-modified AuNPs. The assay, including immunoreaction and detection, can be accomplished in homogeneous solution. In the assay, no tedious and strict stripping of metal nanoparticles, difficult synthesis of labels, multiple steps of immunoreactions and washings, and complicated magnetic separation process were required. The detection limit of human immunoglobulin G (IgG, 3σ) was estimated to be as low as 3.2 × 10−11 g ml−1. The sensitivity was increased by two orders of magnitude over that of other AuNP-based CL immunoassay. The current CL metalloimmunoassay offers the advantages of being simple, cheap, rapid, and sensitive.
Co-reporter:Yingying Qi, Baoxin Li, Furong Xiu
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 Volume 128() pp:76-81
Publication Date(Web):15 July 2014
DOI:10.1016/j.saa.2014.02.139
•For AgNPs’s catalysis on luminol CL system, aggregation was an important factor.•The aggregated AgNPs’s effect characteristic was closely related to AgNPs’s sizes.•Aggregation led to CL increase for 7 nm, decline for 15 nm and no change for 55 nm.•Aggregated AgNPs’s effect is due to electron density’s change in conduction band.We found that after silver nanoparticles (AgNPs) aggregated, its catalytic activity on luminol CL reaction obviously changed, and the change characteristic was closely related to the sizes of AgNPs. UV–visible spectra, X-ray photoelectron spectra, zeta potential and transmission electron microscopy studies were carried out to investigate the CL effect mechanism. The different CL responses of aggregated AgNPs with different size were suggested to be due to the two effects of quantum size and electron density in nanoparticle’s conduction bands, and which one played a major role. The poisonous organic contaminants such as anilines, could induce the aggregation of AgNPs, were observed to affect effectively the luminol–H2O2–7 nm and 15 nm AgNPs CL systems and were detectable by use of a flow injection method with the enhanced or inhibited CL detection.
Co-reporter:Jing Luo, Xiang Cui, Wei Liu, Baoxin Li
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 Volume 131() pp:243-248
Publication Date(Web):15 October 2014
DOI:10.1016/j.saa.2014.04.076
•A universal platform for homogeneous immunoassay was proposed using gold nanoparticles (AuNPs) as label.•This simple protocol consisted of just a one-step incubation followed by injection and reading.•The assay exhibited excellent sensitivity with a detection limit as low as 3 pg/mL.Homogeneous immunoassay is becoming more and more attractive for modern medical diagnosis because it is superior to heterogeneous immunoassay in sample and reagent consumption, analysis time, portability and disposability. Herein, a universal platform for homogeneous immunoassay, using human immunoglobulin G (IgG) as a model analyte, has been developed. This assay relies upon the catalytic activity of gold nanoparticles (AuNPs) on luminol–AgNO3 chemiluminescence (CL) reaction. The immunoreaction of antigen and antibody can induce the aggregation of antibody-functionalized AuNPs, and after aggregation the catalytic activity of AuNPs on luminol–AgNO3 CL reaction is greatly enhanced. Without any separation steps, a CL signal is generated upon addition of a trigger solution, and the CL intensity is directly correlated to the quantity of IgG. The detection limit of IgG was estimated to be as low as 3 pg/mL, and the sensitivity was better than that of the reported AuNPs-based CL immunoassay for IgG.Graphical abstractA novel and sensitive strategy to convert the antibody–antigen recognition event into chemiluminescence signal by employing AuNPs as signaling probes is proposed.
Co-reporter:Junli Zhang, Baoxin Li
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 Volume 125() pp:228-233
Publication Date(Web):5 May 2014
DOI:10.1016/j.saa.2014.01.111
•Fist time study of enhancement of HRP-mimicking DNAzyme on CL emission of CdTe QDs–H2O2 system.•The CL enhancement mechanism was investigated.•The CL system was used to detect sensitively CdTe QDs and HRP-mimicking DNAzyme.In this study, it was found that horseradish peroxidase (HRP)-mimicking DNAzyme could effectively enhance the CL emission of CdTe quantum dots (QDs)–H2O2 system, whereas HRP could not enhance the CL intensity. The CL enhancement mechanism was investigated, and the CL enhancement was supposed to originate from the catalysis of HRP-mimicking DNAzyme on the CL reaction between CdTe QDs and H2O2. Meantime, compared with CdTe QDs–H2O2 CL system, H2O2 concentration was markedly decreased in QDs–H2O2–HRP-mimicking DNAzyme CL system, improving the stability of QDs–H2O2 CL system. The QDs-based CL system was used to detect sensitively CdTe QDs and HRP-mimicking DNAzyme (as biologic labels). This work gives a path for enhancing CL efficiency of QDs system, and will be helpful to promote the step of QDs application in various fields such as bioassay and trace detection of analyte.Horseradish peroxidase (HRP)-mimicking DNAzyme could effectively enhance the CL emission of CdTe quantum dots (QDs)–H2O2 system.
Co-reporter:Chun Chen, Baoxin Li
Biosensors and Bioelectronics 2014 Volume 54() pp:48-54
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.10.050
•We develop a simple chemiluminescence (CL) biosensing platform for site-specific determination of DNA methylation.•The biosensing platform can ever distinguish as low as 0.002% methylation level from the mixture.•The proposed method can also be used to sensitively assay MTase activity with determination limit of 0.007 U/mL.•This assay is homogenous and occurs in the liquid phase, and avoids separation and wash steps.Site-specific determination of DNA methylation and assay of MTase activity can be used for determining specific cancer types, providing insights into the mechanism of gene repression, and developing novel drugs to treat methylation-related diseases. Herein, we develop a simple and highly sensitive chemiluminescence (CL) biosensing platform for site-specific determination of DNA methylation using Exonuclease III (Exo III)-assisted target recycling signal amplification. After bisulfite treatment of mixture of methylated DNA and unmethylated DNA, methylated DNA can hybridize with fluorescein (FAM)-labeled probe DNA to form double-stranded DNA (dsDNA), removing the FAM-labeled probe DNA from the surface of grapheme oxide, and the chemiluminescence resonance energy transfer (CRET) sensing signal can be observed and then amplified using Exo III-based recycling strategy.The biosensing platform exhibits excellent high sensitivity, and it can ever distinguish as low as 0.002% methylation level from the mixture, which is superior to most currently reported methods used for DNA methylation assay. In addition, the proposed method can also be used to sensitively assay MTase activity with determination limit of 0.007 U/mL. This CL biosensing offers the advantages of being facile, sensitive, rapid and cost-effective. These features make the system promising for future use for early cancer diagnosis and discover of new anticancer drugs.
Co-reporter:Chun Chen and Baoxin Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 19) pp:2476-2481
Publication Date(Web):20 Mar 2013
DOI:10.1039/C3TB20270D
We report an amplified chemiluminescence (CL) biosensing platform for ultrasensitive DNA detection. It is based on exonuclease III-assisted target recycling amplification and the super quenching efficiency of graphene oxide (GO). In the presence of target DNA, the target–probe hybrid forms a double-stranded structure, and exonuclease III catalyzes the stepwise removal of mononucleotides from the fluorescein-labeled probe DNA, resulting in the recycling of the target DNA and CL signal amplification of the luminol–H2O2–HRP–fluorescein chemiluminescence resonance energy transfer (CRET) system. The detection limit of target DNA was estimated to be as low as 9 fM, and the sensitivity was about 3 orders of magnitude better than that of GO-based fluorescence resonance energy transfer (FRET) sensors for DNA with exonuclease III-assisted amplification. This CL biosensor offers the advantages of being facile, sensitive, rapid and cost-effective.
Co-reporter:Yuan Gao and Baoxin Li
Analytical Chemistry 2013 Volume 85(Issue 23) pp:11494
Publication Date(Web):November 5, 2013
DOI:10.1021/ac402728d
Detection of ultralow concentration of specific nucleic acid sequences is important in early diagnosis of gene-related diseases and biodefense application. Herein, we report an amplified chemiluminescence (CL) biosensing platform for ultrasensitive DNA detection. It is based on the exonuclease III-assisted target recycling amplification and catalytic effect of G-quadruplex–hemin DNAzyme to stimulate the generation of CL in the presence of H2O2 and luminol. Moreover, the typical problem of high background induced by excess hemin itself can be effectively addressed through the absorbing of superfluous hemin on the surface of single-walled carbon nanotubes and then removing though centrifugation. Therefore, our proposed biosensing exhibited a high sensitivity toward target DNA with a detection limit of 12 fM, which was about 100-fold lower than that of the DNAzyme-based CL sensor for DNA detection without Exo III-assisted amplification. This sensing platform provides a label-free and cost-effective approach for sensitive detection of DNA.
Co-reporter:Shan Ren, Baoxin Li and Lin Zhang
Analyst 2013 vol. 138(Issue 11) pp:3142-3145
Publication Date(Web):28 Mar 2013
DOI:10.1039/C3AN36528J
Positively charged gold nanoparticles can effectively differentiate ATP and ADP, thus providing a simple and visual approach to colorimetric detection of hexokinase activity and inhibition.
Co-reporter:Yuanfu Zhang, Chunli Xu and Baoxin Li
RSC Advances 2013 vol. 3(Issue 17) pp:6044-6050
Publication Date(Web):19 Feb 2013
DOI:10.1039/C3RA22525A
Hemin was assembled on the surface of single-walled carbon nanotubes (SWCNT) through non-covalent functionalization by π–π stacking. The resulting nanohybrid of hemin–SWCNT possessed an intrinsic peroxidase-like activity, and could effectively catalyze oxidation of the substrate 3,3,5,5-tetramethylbenzidine by H2O2 to develop a blue color in aqueous solution. The activity of hemin–SWCNT hybrid material was much higher than the activity of hemin alone. Combination of the catalytic reaction of glucose with glucose oxidase and the hemin–SWCNT hybrid catalytic reaction, a colorimetric method for glucose detection was also developed. The hemin–SWCNT nanohybrid also exhibited high stability and excellent reusability.
Co-reporter:Mei Liu, Baoxin Li, Xiang Cui
Biosensors and Bioelectronics 2013 Volume 47() pp:26-31
Publication Date(Web):15 September 2013
DOI:10.1016/j.bios.2013.02.047
Highlights► It was found that conjugated polyelectrolytes (CPEs) would initiate the strong chemiluminescence (CL) emission of luminol–H2O2 in weak basic media.►The catalytic mechanism of CPEs on luminol–H2O2 CL was discussed in detail.►It was found that the catalytic activity of PMNT (a kind of cationic CPEs) on the luminol–H2O2 CL system was closely relevant to the conformation of PMNT.►The CL intensity of luminol–H2O2–PMNT system in the presence of single-stranded DNA was much larger than that in the presence of double-stranded DNA.►A label-free and homogeneous CL method for DNA hybridization detection was developed.In this study, it was found that conjugated polyelectrolytes (CPEs) would initiate the strong chemiluminescence (CL) emission of luminol–H2O2 in weak basic media. Using CL spectra, ultraviolet visible light spectra, fluorescence spectra and electron spin resonance (ESR) spectra, the catalytic mechanism of CPEs on luminol–H2O2 CL was discussed in detail. Furthermore, it was found that the catalytic activity of poly [3-(3′-N,N,N-triethylamino-1′-propyloxy)-4-methyl-2,5-thiophene hydro chloride] (PMNT) (a kind of cationic CPEs) on the luminol–H2O2 CL system was closely relevant to the conformation of PMNT. The CL intensity of luminol–H2O2–PMNT system in the presence of single-stranded DNA was much larger than that in the presence of double-stranded DNA. By taking advantage of this phenomenon, a label-free and homogeneous CL detection of DNA hybridization is proposed. The detection limit of target DNA (3σ) was estimated to be as low as 3.7×10−13 M. The present CL method for DNA hybridization detection offers the advantages of being simple, cheap, rapid and sensitive.
Co-reporter:Yinping Li;Junli Zhang
Luminescence 2013 Volume 28( Issue 5) pp:667-672
Publication Date(Web):
DOI:10.1002/bio.2413
ABSTRACT
A novel fluorescence assay system for glucose was developed with thioglycollic acid (TGA)-capped CdTe quantum dots (QDs) as probes. The luminescence quantum yield of the TGA-capped CdTe QDs was highly sensitive to H2O2 and pH. In the presence of glucose oxidase, glucose is oxidized to yield, gluconic acid and H2O2. H2O2 and H+ (dissociated from gluconic acid) intensively quenched the fluorescence of QDs. The experimental results showed that the quenched fluorescence was proportional to the glucose concentration within the range of 0.01–5.0 mm under optimized experimental conditions. Compared with most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, high flexibility, and good sensitivity. Furthermore, no complicated chemical modification of QDs and enzyme immobilization was needed in this system. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Yingying Qi, Baoxin Li
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 111() pp:1-6
Publication Date(Web):July 2013
DOI:10.1016/j.saa.2013.03.006
•For AuNPs’s catalysis on luminol CL system, aggregation was an important factor.•The enhanced effect of aggregated AuNPs was closely related to the sizes of AuNPs.•More than one factor influence CL system when reducing group organics exist.•Aggregation induced enhancement was the most key effect in 2.6 nm AuNPs CL system.•Aggregated AuNPs’s enhancement for CL system is due to electronegativity decrease.Some organic compounds containing groups of OH, NH2, or SH, which could induce the aggregation of gold nanoparticles (AuNPs), were observed to enhance effectively the luminol–H2O2–2.6 nm AuNPs CL system. It was found that the aggregation of AuNPs was an important effect factor for the catalytic activity of AuNPs on luminol CL system. The aggregated AuNPs could effectively enhance luminol CL signal compared with the dispersed one. The enhanced effect was closely related to the sizes of AuNPs. Among the studied AuNPs with seven sizes, 2.6 nm AuNPs had the greatest enhancement effect on luminol CL system after its aggregation. The CL enhancement mechanism was investigated, and the marked enhancement of aggregated 2.6 nm AuNPs for luminol CL system was supposed to originate from the decrease of AuNPs’ surface negative charge density compared to its dispersed state. For the luminol–H2O2–2.6 nm AuNPs CL system in the presence of organic compounds containing groups of OH, NH2, or SH, more than one factor played the role in influencing the CL intensity. It was found that the enhanced effect of aggregated 2.6 nm AuNPs induced by such organic compounds was much more significant than the inhibition effect of reducing groups of OH, NH2, or SH, which made it applicable for the determination of this kind of compounds.Graphical abstract
Co-reporter:Xiang Cui, Mei Liu and Baoxin Li
Analyst 2012 vol. 137(Issue 14) pp:3293-3299
Publication Date(Web):01 May 2012
DOI:10.1039/C2AN35328H
Homogeneous immunoassays are becoming more and more attractive for modern medical diagnosis because they are superior to heterogeneous immunoassays in sample and reagent consumption, analysis time, portability and disposability. Herein, a universal platform for homogeneous immunoassay, using human immunoglobulin (IgG) as a model analyte, has been developed. This assay relies upon the inner filter effect (IFE) of gold nanoparticles (AuNPs) on CdTe QDs fluorescence. The immunoreaction of antigen and antibody can induce the aggregation of antibody-functionalized AuNPs, and after aggregation the IFE of AuNPs on CdTe QDs fluorescence is greatly enhanced, resulting in a decrease of fluorescence intensity in the system. Based on this phenomenon, a wide dynamic range of 1–100 pg mL−1 for determination of IgG can be obtained. The proposed method shows a detection limit of 0.3 pg mL−1 for human IgG, which is much lower than the corresponding absorbance-based approach and compares favorably with other reported fluorescent methods. This immunoassay method is simple, rapid, cheap, and sensitive. The proposed method has been successfully applied to measuring IgG in serum samples, and the obtained results agreed well with those of the enzyme-linked immunosorbent assay (ELISA).
Co-reporter:Lihui Fu, Baoxin Li, Yuanfu Zhang
Analytical Biochemistry 2012 Volume 421(Issue 1) pp:198-202
Publication Date(Web):1 February 2012
DOI:10.1016/j.ab.2011.10.021
G-quadruplex ligands can interfere with the telomere structure, telomere elongation/replication, and proliferation of cancer cells. A key element in the development of potent G-quadruplex ligands is the screening of large chemical libraries of potential candidates. Here, we describe a simple fluorescence method for screening of G-quadruplex ligands. The method is based on the ability of G-quadruplex ligands to displace hemin from G-quadruplex-based DNAzyme, resulting in a decrease of its catalytic activity on the fluorescence-developing reaction between p-hydroxyphenylacetic acid and H2O2. The method eliminates the requirement for expensive and time-consuming preparation of labeled DNA. Our method provides a simple, cheap, and sensitive approach to screen G-quadruplex ligands (potential antitumor drugs).
Co-reporter:Rui Cao, Baoxin Li, Yuanfu Zhang and Zhining Zhang
Chemical Communications 2011 vol. 47(Issue 45) pp:12301-12303
Publication Date(Web):17 Oct 2011
DOI:10.1039/C1CC15994A
Positively-charged gold nanoparticles can effectively differentiate long DNA and fragmented DNA, thus providing a simple and visual approach to colorimetric detection of nuclease activity.
Co-reporter:Rui Cao and Baoxin Li
Chemical Communications 2011 vol. 47(Issue 10) pp:2865-2867
Publication Date(Web):19 Jan 2011
DOI:10.1039/C0CC05094F
The electrostatic interaction between the negatively-charged heparin and the positively-charged gold nanoparticles leads to aggregation of gold nanoparticles and a color change from red to blue in solution, thus providing a simple and visual approach to colorimetric detection of heparin.
Co-reporter:Yuanfu Zhang, Baoxin Li and Yan Jin
Analyst 2011 vol. 136(Issue 16) pp:3268-3273
Publication Date(Web):04 Jul 2011
DOI:10.1039/C1AN00002K
We report herein a label-free and sensitive fluorescent method for detection of thrombin using a G-quadruplex-based DNAzyme as the sensing platform. The thrombin-binding aptamer (TBA) is able to bind hemin to form the G-quadruplex-based DNAzyme, and thrombin can significantly enhance the activity of the G-quadruplex-based DNAzyme. The G-quadruplex-based DNAzyme is found to effectively catalyze the H2O2-mediated oxidation of thiamine, giving rise to fluorescence emission. This allows us to utilize the H2O2–thiamine fluorescent system for the quantitative analysis of thrombin. The assay shows a linear toward thrombin concentration in the range of 0.01–0.12 nM. The present limit of detection for thrombin is 1 pM, and the sensitivity for analyzing thrombin is improved by about 10000-fold as compared with the reported colorimetric counterpart. The work also demonstrates that thiamine is an excellent substrate for the fluorescence assay using the G-quadruplex-based DNAzyme as the sensing platform.
Co-reporter:Yanyan Liu, Baoxin Li, Dongmei Cheng, Xiaoyan Duan
Microchemical Journal 2011 Volume 99(Issue 2) pp:503-507
Publication Date(Web):November 2011
DOI:10.1016/j.microc.2011.07.001
In this work, a novel potassium ion (K+) sensor is presented using berberine–G-quadruplex complex as a fluorescent probe. This sensor is based on the K+that can induce the G-rich DNA to form G-quadruplex conformation. The G-quadruplex can bind berberine to form berberine–G-quadruplex complex, resulting in remarkable enhancement of fluorescence emission of the berberine–G-quadruplex system. In the presence of 800 mM sodium ion (Na+), the fluorescence of the berberine–G-quadruplex complex increased linearly with increasing K+ concentration in the range of 0.005–1.0 mM. The turn-on fluorescent assay is simple, inexpensive, and highly sensitive. We observed that Na+ in 10,000-fold molar excess does not interfere. The molecular mechanisms which produce enhanced fluorescence of berberine were discussed.
Co-reporter:Dr. Yingying Qi ;Dr. Baoxin Li
Chemistry - A European Journal 2011 Volume 17( Issue 5) pp:1642-1648
Publication Date(Web):
DOI:10.1002/chem.201001856
Abstract
We report a label-free, aptamer-based chemiluminescent biosensor. The biosensor relies upon the catalytic activity of unmodified gold nanoparticles (AuNPs) on the luminol–H2O2 chemiluminescence (CL) reaction, and the interaction of unmodified AuNPs with the aptamer. The unmodified AuNPs can effectively differentiate unstructured and folded aptamer. The binding of the aptamer with the target can induce the AuNP aggregation in the presence of 0.5 M NaCl, and after aggregation the catalytic activity of the AuNPs on the luminol–H2O2 CL reaction is greatly enhanced. During the assay, no covalent functionalization of the AuNPs or aptamer is required. The detection limit of thrombin was estimated to be as low as 26 fM, and the sensitivity was more than 4 orders of magnitude better than that of known AuNP-based colorimetric methods for the detection of thrombin. This aptamer-based biosensor offers the advantages of being simple, cheap, rapid, and sensitive
Co-reporter:Le Xu, Baoxin Li, Yan Jin
Talanta 2011 Volume 84(Issue 2) pp:558-564
Publication Date(Web):15 April 2011
DOI:10.1016/j.talanta.2011.01.061
We have demonstrated the design of a new type fluorescence assay based on the inner filter effect (IFE) of gold nanoparticles (AuNPs) on the fluorescence of quantum dots (QDs). With a high extinction coefficient, AuNPs are expected to be capable of functioning as powerful absorbers. QDs with tunable emission wavelength are ideal fluorophores because the emission spectra of the rationally synthesized QDs can perfectly overlap with the absorption band of the absorber. Aminothiols are chosen as the model analytes, and the IFE-based fluorescent method for detection of aminothiols was suggested. Under the optimum conditions, the response is linearly proportional to the concentration of cysteine in the range of 0.05–0.9 μg mL−1. The present IFE-based fluorescent strategy could be also used to detect glutathione and homocysteine. The linear concentration ranges were 0.05–1.0 μg mL−1 for glutathione and 0.01–1.0 μg mL−1 for homocysteine.
Co-reporter:Yuanfu Zhang, Baoxin Li
Biosensors and Bioelectronics 2011 Volume 27(Issue 1) pp:137-140
Publication Date(Web):15 September 2011
DOI:10.1016/j.bios.2011.06.030
The G-quadruplex–hemin DNAzyme has shown potential as a new catalytic label for the development of various biosensors. But the typical problem of high background induced by excess hemin itself limits the application of the method. In this work, we found that single-walled carbon nanotubes (SWNTs) can effectively decrease the background of G-quadruplex–hemin DNAzyme sensing platform. The method relies upon the strong affinity of SWNTs with hemin. In the presence of SWNTs, superfluous hemin is arrested the surface of SWNTs, and then is removed though centrifugation It was proved that SWNTs reduce the background of G-quadruplex–hemin DNAzyme sensing platform by ABTS–H2O2 colorimetric. Moreover, we detected K+ with the AGRO100 as the sensing element. The present limit of detection for K+ is 2 nM, and the sensitivity for analyzing K+ is improved by about 10-fold as compared with the reported colorimetric counterpart in the absence of SWNTs.
Co-reporter:Yun Jv, Baoxin Li and Rui Cao
Chemical Communications 2010 vol. 46(Issue 42) pp:8017-8019
Publication Date(Web):27 Sep 2010
DOI:10.1039/C0CC02698K
Positively-charged gold nanoparticles possess intrinsic peroxidase-like activity, and can catalyze oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to develop a blue color in aqueous solution, thus providing a simple approach to colorimetric detection of H2O2 and glucose.
Co-reporter:Li Li, Baoxin Li, Di Cheng, Lihui Mao
Food Chemistry 2010 Volume 122(Issue 3) pp:895-900
Publication Date(Web):1 October 2010
DOI:10.1016/j.foodchem.2010.03.032
We report the development of a simple and rapid colorimetric detection method for melamine in raw milk using gold nanoparticles as probe. This assay relies upon the distance-dependent optical properties of gold nanoparticles. In neutral media, melamine could rapidly induce the aggregation of gold nanoparticles, thereby resulting in red-to-blue (or purple) colour change. The concentration of melamine in raw milk can be determined by monitoring with the naked eye or a UV–vis spectrometer. The present limit of detection for melamine is 0.4 mg/L. The method is rather simple, and the whole process including sample pretreatment takes only 12 min at room temperature. The merits (such as simplicity, rapidity, low cost and visual colorimetry) make the proposed method specially useful for on-site screening melamine levels well below the current safety limit in raw milk.
Co-reporter:Yuanfu Zhang, Baoxin Li and Chunli Xu
Analyst 2010 vol. 135(Issue 7) pp:1579-1584
Publication Date(Web):30 Apr 2010
DOI:10.1039/C0AN00056F
An approach for visual sensing of ascorbic acid is presented. This method is based on the distance-dependent optical property of gold nanoparticles and the Cu+-catalyzed alkyne–azide click reaction. We prepared the terminal azide- and alkyne-functionalized gold nanoparticle probes. In the presence of Cu2+, ascorbic acid could rapidly induce the aggregation of the functionalized gold nanoparticles, thereby resulting in a red-to-purple (or pink) color change. Ascorbic acid can be quantified visually or using a UV-vis spectrometer. The present limit of detection for ascorbic acid is 3 nM. This method exhibits excellent selectivity over other common organic reducing compounds (such as glucose, cysteine, dopamine, thiamine and uric acid). Without the aid of any advanced instruments, the assay of ascorbic acid could be performed with one step at room temperature. This method provides a potentially useful tool for the on-site detection of ascorbic acid.
Co-reporter:Lijuan Zhang, Chunli Xu, Baoxin Li
Microchemical Journal 2010 Volume 95(Issue 2) pp:186-191
Publication Date(Web):July 2010
DOI:10.1016/j.microc.2009.11.011
Water-soluble CdTe quantum dots (QDs) capped with three different thioalkyl acids (mercaptoacetic acid, cysteine and glutathione) were synthesized in aqueous solution. In basic media, K3Fe(CN)6 could directly oxidize the water-soluble CdTe QDs to produce strong CL emission. It was found that the CL intensity depended on the capping ligand and size of CdTe QDs. CL spectra and fluorescence spectra of the system were measured to investigate the CL reaction mechanism. Moreover, the effects of 17 metal ions on the CL system were carefully investigated. Ca2+, Co2+, Mn2+, Hg2+, Mg2+, Cu2+, Ni2+, Cr3+ and Fe3+ could markedly inhibit the CL signal of the K3Fe(CN)6–CdTe QDs system, which makes it applicable for the detection of such ions. This work is of importance for gaining a better understanding of the unique optical and physical chemistry properties of QDs, and it is also helpful to find more practical applications of QDs.
Co-reporter:Yuanfu Zhang;Xingling Chen
Microchimica Acta 2010 Volume 168( Issue 1-2) pp:107-113
Publication Date(Web):2010 February
DOI:10.1007/s00604-009-0269-5
A highly sensitive and selective method is presented for colorimetric determination of dopamine using gold nanoparticles (AuNPs). Dopamine induces the aggregation of AuNPs, this resulting in a color change from red to blue or purple. Aggregation is accelerated by the presence of Cu(II), especially at low concentrations of dopamine. The concentration of dopamine can be quantified visually or using a UV-vis spectrometer. The detection limit is as low as 30 nM. The assay is simple, inexpensive, and highly sensitive. Ascorbic acid in even 100-fold molar excess does not interfere. The mechanism of the aggregation of the AuNPs is discussed.
Co-reporter:Li Li and Baoxin Li
Analyst 2009 vol. 134(Issue 7) pp:1361-1365
Publication Date(Web):02 Apr 2009
DOI:10.1039/B819842J
We report herein the development of a highly sensitive and selective colorimetric detection method for cysteine using gold nanoparticles probes. This assay relies upon the distance-dependent optical properties of gold nanoparticles, the self-assembly of cysteine on gold nanoparticles, and the interaction of a 2:1 cysteine/Cu2+ complex. In the presence of Cu2+, cysteine could rapidly induce the aggregation of gold nanoparticles, thereby resulting in red-to-blue (or purple) color change. The concentration of cysteine can be determined by monitoring with the naked eye or a UV-vis spectrometer. The present limit of detection for cysteine is 10 nM. This method exhibits excellent selectivity for cysteine over other α-amino acids, glutathione, thioglycolic acid and mercaptoethyl alcohol.
Co-reporter:Dongmei Cheng, Baoxin Li
Talanta 2009 Volume 78(Issue 3) pp:949-953
Publication Date(Web):15 May 2009
DOI:10.1016/j.talanta.2009.01.010
A novel fluorometric sensing of malachite green is proposed in this paper. The native double-stranded calf thymus DNA was used as sensing material. In the presence of native double-stranded calf thymus DNA, malachite green could interact with the DNA, which resulted in a strong fluorescence emission. The fluorescent intensity was linear with malachite green concentration in the range of 4.0 × 10−10 − 1.8 × 10−7 g ml−1 and the limit of detection was 2.0 × 10−10 g ml−1. Before fluorescence measurement, the only required operation is the mixing of two solutions. So, this method is rather simple and rapid. The method is very safe for the analyst. Furthermore, the mechanism for fluorescence enhancing of native double-stranded calf thymus DNA on MG was proposed based on a series of experiments. The results suggest that the interaction between MG and calf thymus DNA is intercalation in nature.
Co-reporter:Yingying Qi, Baoxin Li, Zhujun Zhang
Biosensors and Bioelectronics 2009 Volume 24(Issue 12) pp:3581-3586
Publication Date(Web):15 August 2009
DOI:10.1016/j.bios.2009.05.021
We find that the catalytic activity of gold nanoparticles (GNPs) on luminol-H2O2 chemiluminescence (CL) system is greatly enhanced after it is aggregated by 0.5 M NaCl. We use this observation to design a CL detection of DNA hybridization. It is based on that the single- and double-stranded oligonucleotides have different propensities to adsorb on GNPs in colloidal solution, and the hybridization occurred between the probe DNA and target DNA can result in aggregation of the GNPs, producing strong CL emission. In the assay, no covalent functionalization of the GNPs, the probe, or the target DNA is required. The assay, including hybridization and detection, occurs in homogenous solution. The detection limit of target DNA (3σ) was estimated to be as low as 1.1 fM. The sensitivity was increased more than 6 orders of magnitude over that of GNPs-based colorimetric method. The present CL method for DNA hybridization detection offers the advantages of being simple, cheap, rapid and sensitive.
Co-reporter:Yuezhen He
Luminescence 2007 Volume 22(Issue 4) pp:317-325
Publication Date(Web):30 APR 2007
DOI:10.1002/bio.965
In this study, a simple continuous-flow chemiluminescence (CL) system was developed for simultaneous determination of glucose, fructose and lactose in ternary mixtures of reducing sugars without previous separation. This method was based on the different kinetics of the individual sugars in the oxidation reaction with potassium ferricyanide. The known luminol–K3Fe(CN)6 CL system was used to measure the kinetic data of the system. The CL intensity was measured and recorded every second from 1 to 300 s. The data obtained were processed chemometrically using an artificial neural network. The relative standard errors of prediction for three analytes were <5%. The proposed method was successfully applied to the simultaneous determination of the three sugars in some food samples. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:Chun Chen and Baoxin Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 19) pp:NaN2481-2481
Publication Date(Web):2013/03/20
DOI:10.1039/C3TB20270D
We report an amplified chemiluminescence (CL) biosensing platform for ultrasensitive DNA detection. It is based on exonuclease III-assisted target recycling amplification and the super quenching efficiency of graphene oxide (GO). In the presence of target DNA, the target–probe hybrid forms a double-stranded structure, and exonuclease III catalyzes the stepwise removal of mononucleotides from the fluorescein-labeled probe DNA, resulting in the recycling of the target DNA and CL signal amplification of the luminol–H2O2–HRP–fluorescein chemiluminescence resonance energy transfer (CRET) system. The detection limit of target DNA was estimated to be as low as 9 fM, and the sensitivity was about 3 orders of magnitude better than that of GO-based fluorescence resonance energy transfer (FRET) sensors for DNA with exonuclease III-assisted amplification. This CL biosensor offers the advantages of being facile, sensitive, rapid and cost-effective.
Co-reporter:Rui Cao, Baoxin Li, Yuanfu Zhang and Zhining Zhang
Chemical Communications 2011 - vol. 47(Issue 45) pp:NaN12303-12303
Publication Date(Web):2011/10/17
DOI:10.1039/C1CC15994A
Positively-charged gold nanoparticles can effectively differentiate long DNA and fragmented DNA, thus providing a simple and visual approach to colorimetric detection of nuclease activity.
Co-reporter:Rui Cao and Baoxin Li
Chemical Communications 2011 - vol. 47(Issue 10) pp:NaN2867-2867
Publication Date(Web):2011/01/19
DOI:10.1039/C0CC05094F
The electrostatic interaction between the negatively-charged heparin and the positively-charged gold nanoparticles leads to aggregation of gold nanoparticles and a color change from red to blue in solution, thus providing a simple and visual approach to colorimetric detection of heparin.
Co-reporter:Yun Jv, Baoxin Li and Rui Cao
Chemical Communications 2010 - vol. 46(Issue 42) pp:NaN8019-8019
Publication Date(Web):2010/09/27
DOI:10.1039/C0CC02698K
Positively-charged gold nanoparticles possess intrinsic peroxidase-like activity, and can catalyze oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to develop a blue color in aqueous solution, thus providing a simple approach to colorimetric detection of H2O2 and glucose.
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