Immunosensors

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Yaqin Chai - One of the best experts on this subject based on the ideXlab platform.

  • luminescence functionalized metal organic frameworks based on a ruthenium ii complex a signal amplification strategy for electrogenerated chemiluminescence Immunosensors
    Chemistry: A European Journal, 2015
    Co-Authors: Chengyi Xiong, Ruo Yuan, Haijun Wang, Wenbin Liang, Yali Yuan, Yaqin Chai
    Abstract:

    Novel luminescence-functionalized metal–organic frameworks (MOFs) with superior electrogenerated chemiluminescence (ECL) properties were synthesized based on zinc ions as the central ions and tris(4,4′-dicarboxylicacid-2,2′-bipyridyl)ruthenium(II) dichloride ([Ru(dcbpy)3]2+) as the ligands. For potential applications, the synthesized MOFs were used to fabricate a “signal-on” ECL immunosensor for the detection of N-terminal pro-B-type natriuretic peptide (NT-proBNP). As expected, enhanced ECL signals were obtained through a simple fabrication strategy because luminescence-functionalized MOFs not only effectively increased the loading of [Ru(dcbpy)3]2+, but also served as a loading platform in the ECL immunosensor. Furthermore, the proposed ECL immunosensor had a wide linear range from 5 pg mL−1 to 25 ng mL−1 and a relatively low detection limit of 1.67 pg mL−1 (signal/noise=3). The results indicated that luminescence-functionalized MOFs provided a novel amplification strategy in the construction of ECL Immunosensors and might have great prospects for application in bioanalysis.

  • ultrasensitive simultaneous detection of four biomarkers based on hybridization chain reaction and biotin streptavidin signal amplification strategy
    Biosensors and Bioelectronics, 2015
    Co-Authors: Ying Zhuo, Yaqin Chai, Qiang Zhu, Ruo Yuan
    Abstract:

    A sandwich-type electrochemical immunosensor based on redox probe tags identification technology for ultrasensitive simultaneous detection of four antigens was proposed. In this project, well-distributed graphene/gold (GR-Au) hybrid film was acquired through one-step codeposition in an electrode surface and served as the base substrate for immobilizing capture antibodies (Ab1). Hybridization chain reaction (HCR) and biotin/streptavidin (B/SA), combining with gold magnetic nanoparticles were applied to increase the immobilization amount of signal tags in detection antibody (Ab2) bioconjugates. To verify this strategy, four representative biomarkers, a-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA)125 and prostate special antigen (PSA), were used as model analytes. The resulting immunosensor could simultaneously detect four antigens in single-pass differential pulse voltammetry (DPV) scan, and exhibited obviously improved senstivity compared to previous similar Immunosensors, displayed good linear relationships in the ranges from 0.2 to 800 pg/mL for AFP, 0.2 to 600 pg/mL for CEA, 0.2 to 1000 pg/mL for CA125, 0.2 to 800 pg/mL for PSA and with detection limits of 62, 48, 77 and 60 fg/mL, respectively.

  • a sensitive amperometric immunosensor for alpha fetoprotein based on carbon nanotube dna thi nano au modified glassy carbon electrode
    Colloids and Surfaces B: Biointerfaces, 2010
    Co-Authors: Ruo Yuan, Yaqin Chai, Chenglin Hong, Xiaoqing Qian
    Abstract:

    Abstract A novel amperometric immunosensor for the determination of alpha-fetoprotein (AFP) was constructed using films of multi-wall carbon nanotubes/DNA/thionine/gold nanoparticles (nano-Au). Firstly, multi-wall carbon nanotubes (MWCNT) dispersed in poly(diallydimethlammonium chloride) (PDDA) were immobilized on the nano-Au film which was electrochemically deposited on the surface of glassy carbon electrode. Then a negatively charged DNA film was absorbed on the positively charged PDDA. Subsequently, thionine was attached to the electrode via the electrostatic interaction between thionine and the DNA. Finally, the nano-Au was retained on the thionine film for immobilization of AFP antibody (anti-AFP). The modification process was characterized by cyclic voltammetry (CV) and scanning electron microscope (SEM). The factors possibly influenced the performance of the proposed Immunosensors were studied in detail. Under optimal conditions, the proposed immunosensor exhibited good electrochemical behavior to AFP in a two concentration ranges: 0.01–10.0 and 10.0–200.0 ng/mL with a relatively low detection limit of 0.04 ng/mL at three times the background noise. Moreover, the selectivity, repeatability and stability of the proposed immunosensor were acceptable.

  • magnetic core shell fe3o4 ag nanoparticles coated carbon paste interface for studies of carcinoembryonic antigen in clinical immunoassay
    Journal of Physical Chemistry B, 2006
    Co-Authors: Dianping Tang, Ruo Yuan, Yaqin Chai
    Abstract:

    This study demonstrates a novel approach toward development of advanced Immunosensors based on chemically functionalized core−shell Fe3O4@Ag magnetic nanoparticles, and the preparation, characterization, and measurement of relevant properties of the immunosensor useful for the detection of carcinoembryonic antigen (CEA) in clinical immunoassay. The immunosensor based on the combination of a magnetic nanocore and an Ag metallic shell shows good adsorption properties for the attachment of the CEA antibody selective to CEA. The core−shell nanostructure presents good magnetic properties to facilitate and modulate the way it was integrated into a carbon paste. Under optimal conditions, the resulting composite presents good electrochemical response for the detection of CEA, and allows detection of CEA at a concentration as low as 0.5 ng·mL-1. Importantly, the proposed methodology could be extended to the detection of other antigens or biocompounds.

  • amperometric enzyme Immunosensors based on layer by layer assembly of gold nanoparticles and thionine on nafion modified electrode surface for α 1 fetoprotein determinations
    Sensors and Actuators B-chemical, 2006
    Co-Authors: Ying Zhuo, Ruo Yuan, Yaqin Chai, Ying Zhang, Na Wang, Qiang Zhu
    Abstract:

    Abstract A novel amperometric enzyme immunosensor with amplified sensitivity has been developed for the detection of α-1-fetoprotein (AFP) based on layer-by-layer (LBL) assembly of gold nanoparticles (nano-Au) and thionine (Thi) on Nafion (Nf) modified electrode surface by electrostatic adsorption. The stepwise layer-by-layer adsorption interface morphology was further characterized by means of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The enzyme, horseradish peroxidase (HRP), was employed to block the possible remaining active sites of the nano-Au monolayer, avoid the non-specific adsorption instead of bovine serum albumin (BSA) and amplify the response of the antigen–antibody reaction. The performance and factors influencing the performance of the resulting Immunosensors were studied in detail. Tests performed with this immunosensor showed good linearity and specificity when it was evaluated on several standard serum samples and the working range for the system was 1 to 250 ng/ml with a detection limit of 0.56 ng/ml. In addition, the prepared immunosensor could be regenerated 8 times with 4 M urea solution. When the immunosensor was stored at 4 °C and measured intermittently (every 3–5 days), no apparent change was found over 3 months, it yielded a 6.5% R.S.D.

Qin Wei - One of the best experts on this subject based on the ideXlab platform.

  • ultrasensitive electrochemical immunosensor for carbohydrate antigen 72 4 based on dual signal amplification strategy of nanoporous gold and polyaniline au asymmetric multicomponent nanoparticles
    Biosensors and Bioelectronics, 2015
    Co-Authors: Haixia Fan, Zhankui Guo, Liang Gao, Yong Zhang, Dawei Fan, Qin Wei
    Abstract:

    A sandwich electrochemical immunosensor is described for carbohydrate antigen 72-4 (CA72-4) based on a dual amplification strategy with nanoporous gold (NPG) film as the sensor platform and polyaniline-Au asymmetric multicomponent nanoparticles (PANi-Au AMNPs) as labels. In this study, the second anti-CA72-4 antibody (Ab2) adsorbed onto the Au of the PANi-Au AMNPs, which could be simply synthesized by interfacial reaction and have many characteristics of polyaniline and Au nanoparticle, such as well-controlled size, high conductivity, biocompatibility and catalysis. NPG film was used as electrode substrate material to fix a large number of antibodies, due to its unique properties: good biocompatibility, high conductivity, large surface area, and stability. The synergetic of NPG film and PANi-Au AMNPs could increase signal response, and significantly improve sensitivity of the immunosensor. The proposed immunosensor exhibited a wide linear range from 2 to 200 U/mL, with a detection limit of 0.10 U/mL CA72-4, good reproducibility, selectivity and stability. This new type of labels for Immunosensors may provide many potential applications in the detection of carbohydrate antigen in immunoassays.

  • a label free electrochemiluminescence immunosensor based on silver nanoparticle hybridized mesoporous carbon for the detection of aflatoxin b1
    Sensors and Actuators B-chemical, 2014
    Co-Authors: Wei Cao, Tao Yan, Qin Wei
    Abstract:

    Abstract A novel electrochemiluminescence (ECL) immunosensor was fabricated for the detection of Aflatoxin B 1 (AFB 1 ) by luminol functionalized with silver nanoparticles which were loaded on mesoporous carbon (luminol-AgNPs@MC) as antibody carriers and sensing platform. The immunosensor was prepared by modifying luminol-AgNPs@MC which conjugated AFB 1 antibody (anti-AFB 1 ) on glassy carbon electrode. The use of single-step cycle pulse can limit the consecutive reaction between luminol and H 2 O 2 and can be efficient to keep luminol ECL intensity. This proposed method is simple, fast, sensitive, specific, stable and reliable. The results show that the ECL immunosensor has high sensitivity for AFB 1 with a linear range from 0.1 pg/mL to 50 ng/mL and a low detection limit of 50 fg/mL. This work reveals that the luminol-AgNPs@MC is excellent sensing platform for the fabrication of simple and sensitive Immunosensors. Our study provided a promising technique for the quality inspection of agricultural products.

  • copper doped titanium dioxide nanoparticles as dual functional labels for fabrication of electrochemical Immunosensors
    Biosensors and Bioelectronics, 2014
    Co-Authors: Sen Zhang, Tao Yan, Wei Cao, Liangguo Yan, Qin Wei
    Abstract:

    Constructions of versatile electroactive labels are key issues in the development of electrochemical Immunosensors. In this study, copper-doped titanium dioxide nanoparticle (Cu@TiO2) was synthesized and used as labels for fabrication of sandwich-type electrochemical Immunosensors on glassy carbon electrode (GCE). Due to the presence of copper ions, Cu@TiO2 shows a strong response current when coupled to an electrode. The prepared nanocomposite also shows high electrocatalytic activity towards reduction of hydrogen peroxide (H2O2). The dual functionality of Cu@TiO2 enables the fabrication of immunosensor using different detection modes, that is, square wave voltammetry (SWV) or chronoamperometry (CA). While Cu@TiO2 was used as labels of secondary antibodies (Ab2), carboxyl functionalized graphene oxide (CFGO) was used as electrode materials to immobilize primary antibodies (Ab1). Using human immunoglobulin G (IgG) as a model analyte, the immunosensor shows high sensitivity, acceptable stability and good reproducibility for both detection modes. Under optimal conditions, a linear range from 0.1 pg/mL to 100 ng/mL with a detection limit of 0.052 pg/mL was obtained for SWV analysis. For CA analysis, a wider linear range from 0.01 pg/mL to 100 ng/mL and a lower detection limit of 0.0043 pg/mL were obtained. The proposed metal ion-based enzyme-free and noble metal-free immunosensor may have promising applications in clinical diagnoses and many other fields.

  • an ultrasensitive electrochemical immunosensor for the detection of salbutamol based on pd sba 15 and ionic liquid
    Electrochimica Acta, 2012
    Co-Authors: Zhentao Cui, Yanyan Cai, Haixia Fan, Kexia Mao, Huan Wang, Qin Wei
    Abstract:

    Abstract A sandwich-type electrochemical immunosensor for the ultrasensitive detection of the salbutamol (SAL) antigen based on sodium dodecylbenzene sulfonate-functionalized graphene sheets (SDBS-GS), Pd nanoparticles in functionalized SBA-15 (Pd@SBA-15) and ionic liquid (IL) is described. The primary SAL antibody (Ab1) can be covalently attached to the sulfonic groups of SDBS-GS through the amines of Ab1 with an acyl chloride cross-linking reaction. Pd@SBA-15 was prepared by adsorption of H2PdCl4 onto the SBA-15 surface; the adsorbed H2PdCl4 was then reduced to Pd nanoparticles with sodium borohydride. Pd@SBA-15 was conjugated to the secondary SAL antibody (Ab2) through glutaraldehyde. IL was added to the mixture of Pd@SBA-15 and Ab2 to promote electron transport. The synergistic effect between IL and Pd@SBA-15 retained the bioactivity of Ab2. The sensitivity of the sandwich-type immunosensor using Pd@SBA-15/Ab2/IL for the detection of SAL was much higher than those that used either SBA-15/Ab2 or Pd@SBA-15/Ab2. Under optimal conditions, the electrochemical immunosensor exhibited a wide working range from 0.02 to 15.0 ng/mL with a detection limit of 7 pg/mL. The precision, reproducibility and stability of the immunosensor were acceptable. The proposed strategy could be easily extended to fabricate Immunosensors for other tumor markers.

  • electrochemical Immunosensors for cancer biomarker with signal amplification based on ferrocene functionalized iron oxide nanoparticles
    Biosensors and Bioelectronics, 2011
    Co-Authors: Qin Wei, Yanfang Zhao, Yanyan Cai, Zhiyong Qian, Minghui Yang
    Abstract:

    Abstract Ultrasensitive sandwich type electrochemical Immunosensors for the detection of cancer biomarker prostate specific antigen (PSA) is described which uses graphene sheet (GS) sensor platform and ferrocene functionalized iron oxide (Fe 3 O 4 ) as label. To fabricate the labels, dopamine (DA) was first anchored onto Fe 3 O 4 surface followed by conjugating ferrocene monocarboxylic acid (FC) and secondary-antibody (Ab 2 ) onto Fe 3 O 4 through the amino groups of DA (DA-Fe 3 O 4 -FC-Ab 2 ). The great amount of DA molecules anchored onto Fe 3 O 4 surface increased the immobilization of FC and Ab 2 onto the Fe 3 O 4 nanoparticle, which in turn increased the sensitivity of the immunosensor. GS used as biosensor platform increased the surface area to capture a great amount of primary antibodies (Ab 1 ) and the good conductivity of GS enhanced the detection sensitivity to FC. Using the redox current of FC as signal, the immunosensor displays high sensitivity, wide linear range (0.01–40 ng/mL), low detection limit (2 pg/mL), good reproducibility and stability. In addition, this method could be extended to the immobilization of other interesting materials (fluorescence dyes) onto Fe 3 O 4 for preparing various kinds of labels to meet the different requirements in immunoassays.

Ruo Yuan - One of the best experts on this subject based on the ideXlab platform.

  • luminescence functionalized metal organic frameworks based on a ruthenium ii complex a signal amplification strategy for electrogenerated chemiluminescence Immunosensors
    Chemistry: A European Journal, 2015
    Co-Authors: Chengyi Xiong, Ruo Yuan, Haijun Wang, Wenbin Liang, Yali Yuan, Yaqin Chai
    Abstract:

    Novel luminescence-functionalized metal–organic frameworks (MOFs) with superior electrogenerated chemiluminescence (ECL) properties were synthesized based on zinc ions as the central ions and tris(4,4′-dicarboxylicacid-2,2′-bipyridyl)ruthenium(II) dichloride ([Ru(dcbpy)3]2+) as the ligands. For potential applications, the synthesized MOFs were used to fabricate a “signal-on” ECL immunosensor for the detection of N-terminal pro-B-type natriuretic peptide (NT-proBNP). As expected, enhanced ECL signals were obtained through a simple fabrication strategy because luminescence-functionalized MOFs not only effectively increased the loading of [Ru(dcbpy)3]2+, but also served as a loading platform in the ECL immunosensor. Furthermore, the proposed ECL immunosensor had a wide linear range from 5 pg mL−1 to 25 ng mL−1 and a relatively low detection limit of 1.67 pg mL−1 (signal/noise=3). The results indicated that luminescence-functionalized MOFs provided a novel amplification strategy in the construction of ECL Immunosensors and might have great prospects for application in bioanalysis.

  • ultrasensitive simultaneous detection of four biomarkers based on hybridization chain reaction and biotin streptavidin signal amplification strategy
    Biosensors and Bioelectronics, 2015
    Co-Authors: Ying Zhuo, Yaqin Chai, Qiang Zhu, Ruo Yuan
    Abstract:

    A sandwich-type electrochemical immunosensor based on redox probe tags identification technology for ultrasensitive simultaneous detection of four antigens was proposed. In this project, well-distributed graphene/gold (GR-Au) hybrid film was acquired through one-step codeposition in an electrode surface and served as the base substrate for immobilizing capture antibodies (Ab1). Hybridization chain reaction (HCR) and biotin/streptavidin (B/SA), combining with gold magnetic nanoparticles were applied to increase the immobilization amount of signal tags in detection antibody (Ab2) bioconjugates. To verify this strategy, four representative biomarkers, a-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA)125 and prostate special antigen (PSA), were used as model analytes. The resulting immunosensor could simultaneously detect four antigens in single-pass differential pulse voltammetry (DPV) scan, and exhibited obviously improved senstivity compared to previous similar Immunosensors, displayed good linear relationships in the ranges from 0.2 to 800 pg/mL for AFP, 0.2 to 600 pg/mL for CEA, 0.2 to 1000 pg/mL for CA125, 0.2 to 800 pg/mL for PSA and with detection limits of 62, 48, 77 and 60 fg/mL, respectively.

  • a sensitive amperometric immunosensor for alpha fetoprotein based on carbon nanotube dna thi nano au modified glassy carbon electrode
    Colloids and Surfaces B: Biointerfaces, 2010
    Co-Authors: Ruo Yuan, Yaqin Chai, Chenglin Hong, Xiaoqing Qian
    Abstract:

    Abstract A novel amperometric immunosensor for the determination of alpha-fetoprotein (AFP) was constructed using films of multi-wall carbon nanotubes/DNA/thionine/gold nanoparticles (nano-Au). Firstly, multi-wall carbon nanotubes (MWCNT) dispersed in poly(diallydimethlammonium chloride) (PDDA) were immobilized on the nano-Au film which was electrochemically deposited on the surface of glassy carbon electrode. Then a negatively charged DNA film was absorbed on the positively charged PDDA. Subsequently, thionine was attached to the electrode via the electrostatic interaction between thionine and the DNA. Finally, the nano-Au was retained on the thionine film for immobilization of AFP antibody (anti-AFP). The modification process was characterized by cyclic voltammetry (CV) and scanning electron microscope (SEM). The factors possibly influenced the performance of the proposed Immunosensors were studied in detail. Under optimal conditions, the proposed immunosensor exhibited good electrochemical behavior to AFP in a two concentration ranges: 0.01–10.0 and 10.0–200.0 ng/mL with a relatively low detection limit of 0.04 ng/mL at three times the background noise. Moreover, the selectivity, repeatability and stability of the proposed immunosensor were acceptable.

  • magnetic core shell fe3o4 ag nanoparticles coated carbon paste interface for studies of carcinoembryonic antigen in clinical immunoassay
    Journal of Physical Chemistry B, 2006
    Co-Authors: Dianping Tang, Ruo Yuan, Yaqin Chai
    Abstract:

    This study demonstrates a novel approach toward development of advanced Immunosensors based on chemically functionalized core−shell Fe3O4@Ag magnetic nanoparticles, and the preparation, characterization, and measurement of relevant properties of the immunosensor useful for the detection of carcinoembryonic antigen (CEA) in clinical immunoassay. The immunosensor based on the combination of a magnetic nanocore and an Ag metallic shell shows good adsorption properties for the attachment of the CEA antibody selective to CEA. The core−shell nanostructure presents good magnetic properties to facilitate and modulate the way it was integrated into a carbon paste. Under optimal conditions, the resulting composite presents good electrochemical response for the detection of CEA, and allows detection of CEA at a concentration as low as 0.5 ng·mL-1. Importantly, the proposed methodology could be extended to the detection of other antigens or biocompounds.

  • amperometric enzyme Immunosensors based on layer by layer assembly of gold nanoparticles and thionine on nafion modified electrode surface for α 1 fetoprotein determinations
    Sensors and Actuators B-chemical, 2006
    Co-Authors: Ying Zhuo, Ruo Yuan, Yaqin Chai, Ying Zhang, Na Wang, Qiang Zhu
    Abstract:

    Abstract A novel amperometric enzyme immunosensor with amplified sensitivity has been developed for the detection of α-1-fetoprotein (AFP) based on layer-by-layer (LBL) assembly of gold nanoparticles (nano-Au) and thionine (Thi) on Nafion (Nf) modified electrode surface by electrostatic adsorption. The stepwise layer-by-layer adsorption interface morphology was further characterized by means of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The enzyme, horseradish peroxidase (HRP), was employed to block the possible remaining active sites of the nano-Au monolayer, avoid the non-specific adsorption instead of bovine serum albumin (BSA) and amplify the response of the antigen–antibody reaction. The performance and factors influencing the performance of the resulting Immunosensors were studied in detail. Tests performed with this immunosensor showed good linearity and specificity when it was evaluated on several standard serum samples and the working range for the system was 1 to 250 ng/ml with a detection limit of 0.56 ng/ml. In addition, the prepared immunosensor could be regenerated 8 times with 4 M urea solution. When the immunosensor was stored at 4 °C and measured intermittently (every 3–5 days), no apparent change was found over 3 months, it yielded a 6.5% R.S.D.

Minghui Yang - One of the best experts on this subject based on the ideXlab platform.

  • graphene oxide quantum dots silver core shell nanocrystals as turn on fluorescent nanoprobe for ultrasensitive detection of prostate specific antigen
    Biosensors and Bioelectronics, 2015
    Co-Authors: Haimeng Pei, Minghui Yang, Shuyun Zhu, Rongmei Kong, Yiqun Zheng
    Abstract:

    We report a fluorescent turn-on nanoprobe for ultrasensitive detection of prostate specific antigen (PSA) based on graphene oxide quantum dots@silver (GQDs@Ag) core-shell nanocrystals. The success of this work relies on the assembly of quantities of GQDs in one GQDs@Ag probe, which makes the ratio of probe to target significantly increased and thus enables the fluorescent signal enhancement. When the silver shell was removed via oxidative etching using hydrogen peroxide (H2O2), the incorporated GQDs could be readily released and the whole process caused little change to their fluorescence performance. We tested the probe for the ultrasensitive detection of PSA based on the sandwich protocol of Immunosensors. In particular, magnetic beads (MBs) were employed to immobilize anti-PSA antibody (Ab1) and acted as a separable capture probe, while GQDs@Ag was used as detection probe by linking antibody (Ab2). The developed immunosensor showed a good linear relationship between the fluorescence intensity and the concentration of PSA in the range from 1 pg/mL to 20 ng/mL with a detection limit of 0.3 pg/mL. The immunosensor used for the analysis of clinical serum samples exhibited satisfactory results, which demonstrated its potential for practical diagnostic applications. This method provides a possible solution to the application of GQDs in immunosensing and could be potentially extended to other similar systems.

  • electrochemical Immunosensors for cancer biomarker with signal amplification based on ferrocene functionalized iron oxide nanoparticles
    Biosensors and Bioelectronics, 2011
    Co-Authors: Qin Wei, Yanfang Zhao, Yanyan Cai, Zhiyong Qian, Minghui Yang
    Abstract:

    Abstract Ultrasensitive sandwich type electrochemical Immunosensors for the detection of cancer biomarker prostate specific antigen (PSA) is described which uses graphene sheet (GS) sensor platform and ferrocene functionalized iron oxide (Fe 3 O 4 ) as label. To fabricate the labels, dopamine (DA) was first anchored onto Fe 3 O 4 surface followed by conjugating ferrocene monocarboxylic acid (FC) and secondary-antibody (Ab 2 ) onto Fe 3 O 4 through the amino groups of DA (DA-Fe 3 O 4 -FC-Ab 2 ). The great amount of DA molecules anchored onto Fe 3 O 4 surface increased the immobilization of FC and Ab 2 onto the Fe 3 O 4 nanoparticle, which in turn increased the sensitivity of the immunosensor. GS used as biosensor platform increased the surface area to capture a great amount of primary antibodies (Ab 1 ) and the good conductivity of GS enhanced the detection sensitivity to FC. Using the redox current of FC as signal, the immunosensor displays high sensitivity, wide linear range (0.01–40 ng/mL), low detection limit (2 pg/mL), good reproducibility and stability. In addition, this method could be extended to the immobilization of other interesting materials (fluorescence dyes) onto Fe 3 O 4 for preparing various kinds of labels to meet the different requirements in immunoassays.

  • electrochemical immunosensor for norethisterone based on signal amplification strategy of graphene sheets and multienzyme functionalized mesoporous silica nanoparticles
    Biosensors and Bioelectronics, 2010
    Co-Authors: Qin Wei, Xiaodong Xin, Yanyan Han, Yanfang Zhao, Yanyan Cai, Minghui Yang
    Abstract:

    Abstract Norethisterone is one kind of widely used anabolic steroid hormones which can help to promote livestock growth and sometime has been illegally used for livestock breeding. The residues of norethisterone in animal food will harm people's health, therefore, it has been banned to use for the growth promotion purposes in livestock. In this study, amino-group functionalized mesoporous silica nanoparticles (MSN) were prepared and used to immobilize Au nanoparticles, which was further utilized for the adsorption of horseradish peroxidase (HRP) and the secondary antibody (Ab 2 ). The resulting nanoparticles, Au-MSN-HRP-Ab 2 were used as labels for Immunosensors to detect norethisterone antigen. A sandwich-type protocol was used to prepare the immunosensor with the primary antibody (Ab 1 ) immobilized onto thionine (TH) and graphene sheet (GS) modified glassy carbon electrode surface. The sensitivity of the sandwich-type immunosensor using Au-MSN-HRP-Ab 2 as labels for norethisterone antigen detection was much higher than that using either Au-MSN-Ab 2 or MSN-HRP-Ab 2 as labels. Within norethisterone concentration range (0.01–10 ng/mL), a linear calibration plot ( Y  = 0.55671 + 8.27101 X , r  = 0.9993) was obtained with a detection limit of 3.58 pg/mL under optimal conditions. The proposed immunosensor shows good reproducibility, selectivity, and acceptable stability. This new type of labels for Immunosensors may provide many potential applications for the detection of growth hormone in animal derived food.

  • dumbbell like au fe3o4 nanoparticles as label for the preparation of electrochemical Immunosensors
    Biosensors and Bioelectronics, 2010
    Co-Authors: Qin Wei, Zhi Xiang, Gaolei Wang, Zhiyong Qian, Minghui Yang
    Abstract:

    Abstract In this work, we developed a novel kind of label based on dumbbell-like Au-Fe 3 O 4 nanoparticles (NPs) for the preparation of electrochemical immunosensor for the detection of cancer biomarker prostate specific antigen (PSA). The signal amplification strategy, using the synergetic effect present in Au-Fe 3 O 4 to increase the reduction ability of the NPs toward H 2 O 2 , improves the sensitivity and detection limit of the immunosensor. With primary anti-PSA antibody (Ab 1 ) immobilized onto graphene surface and secondary anti-PSA antibody (Ab 2 ) adsorbed onto the Au of the Au-Fe 3 O 4 NPs, the immunosensor prepared through a sandwich structure displays a wide linear range (0.01–10 ng/mL), low detection limit (5 pg/mL), good reproducibility and stability. These labels for Immunosensors may provide many potential applications for the detection of different biomolecules.

  • fe3o4 nanoparticles loaded peg pla polymeric vesicles as labels for ultrasensitive Immunosensors
    Biomaterials, 2010
    Co-Authors: Qin Wei, Gaolei Wang, Zhiyong Qian, Minghui Yang
    Abstract:

    Abstract A class of immuno-labels based on poly(ethylene glycol)–poly(lactic acid) (PEG–PLA) polymeric vesicles was developed in this study. To fabricate these immune-labels, the uniform Fe 3 O 4 nanoparticles (NPs) were loaded into the vesicles followed by conjugating secondary antibody (Ab 2 ) onto the vesicles surface, named Ab 2 –PEG–PLA–Fe 3 O 4 . The resulting Ab 2 –PEG–PLA–Fe 3 O 4 demonstrated high catalytic activity towards H 2 O 2 , and the sensitivity of the sandwich-type immunosensor using this label for prostate specific antigen (PSA) detection increased greatly. The immunosensor based on this label exhibited high sensitivity, wide linear range (0.005–10 ng/mL), low detection limit (2 pg/mL), good reproducibility, selectivity and stability. These labels for Immunosensors may provide many potential applications for the ultrasensitive detection of different cancer biomarkers. In addition, this technique also has the potential to be extended to the loading of other interesting material for preparing various kinds of labels to meet the different requirements in immunoassays.

Dianping Tang - One of the best experts on this subject based on the ideXlab platform.

  • graphene oxide labeled sandwich type impedimetric immunoassay with sensitive enhancement based on enzymatic 4 chloro 1 naphthol oxidation
    Biosensors and Bioelectronics, 2013
    Co-Authors: Li Hou, Yuling Cui, Zhuangqiang Gao, Jianxin Huang, Dianping Tang
    Abstract:

    Abstract A new sandwich-type impedimetric immunosensor based on functionalized graphene oxide nanosheets with a high ratio of horseradish peroxidase (HRP) and detection antibody was developed for the detection of carcinoembryonic antigen (CEA) by coupling with enzymatic biocatalytic precipitation of 4-chloro-1-naphthol (4-CN) on the captured antibody-modified glassy carbon electrode. Two molecular tags (with and without the graphene oxide nanosheets) were investigated for the detection of CEA and improved analytical features were acquired with the graphene-based labeling. With the labeling method, the performance and factors influencing the properties of the impedimetric Immunosensors were also studied and evaluated. Under the optimal conditions, the dynamic concentration range of the impedimetric Immunosensors spanned from 1.0 pg mL −1 to 80 ng mL −1 CEA with a detection limit (LOD) of 0.64 pg mL −1 . Intra- and inter-assay coefficients of variation were less than 7.5% and 11%, respectively. Additionally, the methodology was evaluated for CEA analysis of 10 clinical serum samples and 5 diluted serum samples, receiving in a good accordance with the results obtained by the impedimetric immunoassay and the commercialized electrochemiluminescent method.

  • one step electrochemical immunosensing for simultaneous detection of two biomarkers using thionine and ferrocene as distinguishable signal tags
    Mikrochimica Acta, 2012
    Co-Authors: Wenqiang Lai, Junyang Zhuang, Juan Tang, Guonan Chen, Dianping Tang
    Abstract:

    We report on a new kind of electrochemical Immunosensors for simultaneous determination of the biomarkers carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). Thionine and ferrocene were applied as distinguishable electrochemical tags (and mediators) which were covalently conjugated on anti-AFP and anti-CEA antibodies, respectively, via carboxy groups. The resulting conjugates were co-immobilized on a glassy carbon electrode functionalized with gold nanoparticles. Finally, horseradish peroxidase (HRP) was immobilized onto the modified electrode. Labeled thionine and ferrocene, respectively, act as distinguishable tags for simultaneous determination of AFP and CEA due to the difference in the location of their voltammetric peaks. With a one-step immunoassay format, the analytes in the sample produced transparent immunoaffinity reaction with the corresponding antibodies on the electrode. Once the immunocomplex is formed, it partially inhibits the active center of the immobilized HRP, and this decreased the activity of HRP in terms of reduction of hydrogen peroxide. This immunosensor enables the simultaneous determination of AFP and CEA in a single run and within the same dynamic range (0.01–50 ng mL−1) and the same lower detection limit (0.01 ng mL−1). The reproducibility and stability of the Immunosensors are acceptable. The dual immunosensor was applied to evaluate several specimens, and the assay results are in acceptable agreement with clinical data.

  • magnetic mesoporous organic inorganic nico2o4 hybrid nanomaterials for electrochemical Immunosensors
    ACS Applied Materials & Interfaces, 2011
    Co-Authors: Lingxing Zeng, Dianping Tang, Guonan Chen, Jinchao Wang, Bingqian Liu, Mingdeng Wei
    Abstract:

    This study demonstrates a facile and feasible strategy toward the development of advanced electrochemical Immunosensors based on chemically functionalized magnetic mesoporous organic−inorganic hybrid nanomaterials, and the preparation, characterization, and measurement of relevant properties of the immunosensor for detection of carcinoembryonic antigen (CEA, as a model analyte) in clinical immunoassays. The as-prepared nanomaterials composed of a magnetic mesoporous NiCo2O4 nanosheet, an interlayer of Nafion/thionine organic molecules and a nanogold layer show good adsorption properties for the attachment of horseradish peroxidase-labeled secondary anti-CEA antibody (HRP-anti-CEA). With a sandwich-type immunoassay format, the functional bionanomaterials present good analytical properties to facilitate and modulate the way it was integrated onto the electrochemical Immunosensors, and allows the detection of CEA at a concentration as low as 0.5 pg/mL. Significantly, the immunosensor could be easily regenera...

  • magnetic core shell fe3o4 ag nanoparticles coated carbon paste interface for studies of carcinoembryonic antigen in clinical immunoassay
    Journal of Physical Chemistry B, 2006
    Co-Authors: Dianping Tang, Ruo Yuan, Yaqin Chai
    Abstract:

    This study demonstrates a novel approach toward development of advanced Immunosensors based on chemically functionalized core−shell Fe3O4@Ag magnetic nanoparticles, and the preparation, characterization, and measurement of relevant properties of the immunosensor useful for the detection of carcinoembryonic antigen (CEA) in clinical immunoassay. The immunosensor based on the combination of a magnetic nanocore and an Ag metallic shell shows good adsorption properties for the attachment of the CEA antibody selective to CEA. The core−shell nanostructure presents good magnetic properties to facilitate and modulate the way it was integrated into a carbon paste. Under optimal conditions, the resulting composite presents good electrochemical response for the detection of CEA, and allows detection of CEA at a concentration as low as 0.5 ng·mL-1. Importantly, the proposed methodology could be extended to the detection of other antigens or biocompounds.

  • electrochemical immuno bioanalysis for carcinoma antigen 125 based on thionine and gold nanoparticles modified carbon paste interface
    Analytica Chimica Acta, 2006
    Co-Authors: Dianping Tang, Ruo Yuan, Yaqin Chai
    Abstract:

    Abstract A novel electrochemical immunosensor for the determination of carcinoma antigen 125 (CA125) was developed by means of immobilizing CA125 antibody (anti-CA125) on gold nanoparticles (Au) and thionine (Thi)-modified carbon paste interface. To avoid the leak of hydrophilic gold nanoparticles and thionine from carbon paste interface, the Au–Thi-modified carbon paste electrodes (CPEs) were first treated in the mixture solution containing 10% HNO3 and 2.5% K2Cr2O7 for 1.5 min at +1.5 V to make the carbon surface with –COOH groups, which can react with –NH2 groups on the thionine molecule, in the meantime, gold nanoparticles were absorbed on the thionine surface. Subsequently, CA125 antibodies were assembled onto the surface of gold nanoparticles. The fabrication process of the immunosensor was characterized by fourier transform infrared spectroscopy (FTIR) and UV–vis absorption spectroscopy. The performance and factors influencing the performance of the immunosensor were studied in detail. A direct electrochemical immunoassay format was employed to detect CA125 antigen based on the current change before and after the antigen–antibody reaction. The current change was proportional to CA125 concentration ranging from 10 to 30 U/ml with a detection limit of 1.8 U/ml (at 3δ). The Immunosensors were used to analyze CA125 in human serum specimens. Analytical results of clinical samples show that the developed immunoassay has a promising alternative approach for detecting CA125 in the clinical diagnosis.