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José M. Pingarrón - One of the best experts on this subject based on the ideXlab platform.

  • Determination of progesterone in saliva using an electrochemical Immunosensor and a COTS-based portable potentiostat.
    Analytica Chimica Acta, 2018
    Co-Authors: Verónica Serafín, G. Martínez-garcía, Juan Aznar-poveda, Jose Antonio Lopez-pastor, Antonio-javier Garcia-sanchez, Joan Garcia-haro, Susana Campuzano, P. Yáñez-sedeño, José M. Pingarrón
    Abstract:

    Abstract This paper describes the reliable determination of progesterone (P4) in undiluted saliva making use of a disposable amperometric Immunosensors implemented on low-cost and portable device/potentiostat constructed with commercial-off-the-shelf (COTS) components. The Immunosensor allows the fast (45 min), selective and sensitive determination (5 pg mL−1 LOD) of P4 using amperometry in stirred solutions. The Immunosensor was coupled to the COTS-based potentiostat and amperometry was made into drops of quiescent solutions. No significant differences were apparent between the analytical performance achieved with the Immunosensor for P4 using both a conventional and the COST-based potentiostats. The practical applicability of the Immunosensor coupled with the COTS-based potentiostat was demonstrated by determining the endogenous P4 content in different undiluted saliva samples with highly variable endogenous contents of the target hormone. The obtained results were in good agreement with those provided by the conventional ELISA methodology and with the contents reported in the literature for samples with similar characteristics. This validated the combined device for the reliable and minimally invasive determination of the target hormone involving a very simple protocol and taking only 45 min.

  • an electrochemical Immunosensor for brain natriuretic peptide prepared with screen printed carbon electrodes nanostructured with gold nanoparticles grafted through aryl diazonium salt chemistry
    Talanta, 2018
    Co-Authors: Verónica Serafín, Susana Campuzano, José M. Pingarrón, Rebeca M Torrenterodriguez, A Gonzalezcortes, Garcia P De Frutos, M Sabate, P Yanezsedeno
    Abstract:

    Abstract A sensitive amperometric Immunosensor has been prepared by immobilization of capture antibodies onto gold nanoparticles (AuNPs) grafted on a screen-printed carbon electrode (SPCE) through aryl diazonium salt chemistry using 4-aminothiophenol (AuNPs-S-Phe-SPCE). The Immunosensor was designed for the accurate determination of clinically relevant levels of B-type natriuretic peptide (BNP) in human serum samples. The nanostructured electrochemical platform resulted in an ordered layer of AuNPs onto SPCEs which combined the advantages of high conductivity and improved stability of immobilized biomolecules. The resulting disposable Immunosensor used a sandwich type immunoassay involving a peroxidase-labeled detector antibody. The amperometric transduction was carried out at −0.20 V (vs the Ag pseudo-reference electrode) upon the addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. The nanostructured Immunosensors show a storage stability of at least 25 days, a linear range between 0.014 and 15 ng mL−1, and a LOD of 4 pg mL−1, which is 100 times lower than the established cut-off value for heart failure (HF) diagnosis. The performance of the Immunosensor is advantageously compared with that provided with Immunosensors prepared by grafting SPCE with p-phenylendiamine (H2N-Phe-SPCE) and attaching AuNPs by immersion into an AuNPs suspension or by electrochemical deposition, as well as with Immunosensors constructed using commercial AuNPs-modified SPCEs. The developed Immunosensor was applied to the successful analysis of human serum from heart failure (HF) patients upon just a 10-times dilution as sample treatment.

  • Comparative evaluation of the performance of electrochemical Immunosensors using magnetic microparticles and nanoparticles. Application to the determination of tyrosine kinase receptor AXL
    Microchimica Acta, 2017
    Co-Authors: V. Serafín, P. Yáñez-sedeño, R. M. Torrente-rodríguez, M. Batlle, P. García De Frutos, S. Campuzano, José M. Pingarrón
    Abstract:

    Electrochemical sandwich immunoassay strategies involving the use of carboxyl-functionalized magnetic microbeads (cMBs) and magnetic nanoparticles (cMNPs) have been evaluated and compared. The proteolytically cleaved soluble tyrosine kinase receptor sAXL was used as the target analyte. Antibodies against AXL were covalently immobilized on cMBs or cMNPs. Immunobinding of AXL was detected by means of a secondary biotinylated antibody and a streptavidin-horseradish peroxidase conjugate. The electrochemical transduction was accomplished by capturing the cMBs or cMNPs bearing the immunoconjugates onto screen-printed carbon electrodes (SPCEs) by using a small magnet. The amperometric response was measured at −0.20 V (vs the silver pseudo-reference electrode of the SPCE) upon the addition of H_2O_2 in the presence of hydroquinone as the redox mediator. The calibration plots for AXL extended up to 7.5 ng mL^−1 when cMBs were used for the preparation of the Immunosensor and up to 40 ng mL^−1 in the case of using cMNPs. The respective slope values were 158 (cMBs) and 43 nA mL ng^−1 (cMNPs), while the achieved LODs were 74 (cMBs) and 75 pg mL^−1 (cMNPs). Although the Immunosensors prepared with cMBs provided a shorter range of linearity, they exhibited a 3.7-times larger sensitivity than those constructed with cMNPs. The successful application of the new strategies was demonstrated for the determination of the endogenous content of sAXL in real human serum samples (a cut-off value of 71 ng mL^−1 have been established for patients with risk of heart failure). The Immunosensors constructed using cMBs or cMNPs can be advanta geously compared, in terms of sensitivity and fabrication time, with the only Immunosensor for AXL previously reported. In addition, these new Immunosensors took approximately half time than ELISA to perform the assay. Graphical abstract Comparative evaluation of the performance of amperometric Immunosensors for tyrosine kinase receptor AXL determination using carboxyl-modified magnetic microparticles (cMBs) and nanoparticles (cMNPs) and application to the determination of the endogeneous concentration in real human serum samples.

  • A disposable electrochemical Immunosensor for prolactin involving affinity reaction on streptavidin-functionalized magnetic particles.
    Analytica Chimica Acta, 2011
    Co-Authors: María Moreno-guzmán, P. Yáñez-sedeño, Araceli González-cortés, José M. Pingarrón
    Abstract:

    Abstract A novel electrochemical Immunosensor was developed for the determination of the hormone prolactin. The design involved the use of screen-printed carbon electrodes and streptavidin-functionalized magnetic particles. Biotinylated anti-prolactin antibodies were immobilized onto the functionalized magnetic particles and a sandwich-type immunoassay involving prolactin and anti-prolactin antibody labelled with alkaline phosphatase was employed. The resulting bio-conjugate was trapped on the surface of the screen-printed electrode with a small magnet and prolactin quantification was accomplished by differential pulse voltammetry of 1-naphtol formed in the enzyme reaction using 1-naphtyl phosphate as alkaline phosphatase substrate. All variables involved in the preparation of the Immunosensor and in the electrochemical detection step were optimized. The calibration plot for prolactin exhibited a linear range between 10 and 2000 ng mL−1 with a slope value of 7.0 nA mL ng−1. The limit of detection was 3.74 ng mL−1. Furthermore, the modified magnetic beads–antiprolactin conjugates showed an excellent stability. The Immunosensor exhibited also a high selectivity with respect to other hormones. The analytical usefulness of the immnunosensor was demonstrated by analyzing human sera spiked with prolactin at three different concentration levels.

  • An electrochemical Immunosensor for testosterone using functionalized magnetic beads and screen-printed carbon electrodes
    Biosensors and Bioelectronics, 2010
    Co-Authors: Marcos Eguílaz, Susana Campuzano, P. Yáñez-sedeño, María Moreno-guzmán, Araceli González-cortés, José M. Pingarrón
    Abstract:

    Abstract A disposable electrochemical Immunosensor using screen-printed carbon electrodes (SPCEs) and protein A-functionalized magnetic beads (MBs) was developed for the determination of testosterone. Anti-testosterone was immobilized onto MBs and a direct competitive immunoassay involving testosterone labeled with peroxidase (HRP) was performed. The resulting conjugate was trapped on the SPCE with a small magnet. Testosterone determination was carried out by amperometry at −0.2 V upon H2O2 additions using hydroquinone (HQ) as the redox mediator. The experimental variables involved in the Immunosensor response to testosterone were evaluated. Under the optimized conditions, a calibration plot for testosterone was obtained with a linear range between 5.0 × 10−3 and 50 ng/mL (r = 0.995). The detection limit was 1.7 pg/mL and the EC50 was 0.25 ± 0.04 ng/mL. These characteristics are notably better than those achieved with other reported Immunosensors. Furthermore, anti-testosterone/MBs conjugates were shown to be stable for at least 25 days. A good selectivity was also found against other steroid hormones. The usefulness of the Immunosensor was demonstrated by analyzing human serum spiked with 1 and 10 ng/mL testosterone.

Danny K.y. Wong - One of the best experts on this subject based on the ideXlab platform.

  • Detection of estradiol at an electrochemical Immunosensor with a Cu UPD|DTBP-Protein G scaffold.
    Biosensors & bioelectronics, 2012
    Co-Authors: Xiaoqiang Liu, Heqing Feng, Xiuhua Liu, Xinhai Wang, Jiamei Zhang, Danny K.y. Wong
    Abstract:

    A copper monolayer was formed on a gold electrode surface via underpotential deposition (UPD) method to construct a Cu UPD|DTBP-Protein G Immunosensor for the sensitive detection of 17β-estradiol. Copper UPD monolayer can minimize the non-specific adsorption of biological molecules on the Immunosensor surface and enhance the binding efficiency between Immunosensor surface and thiolated Protein G. The crosslinker DTBP (Dimethyl 3,3'-dithiobispropionimidate · 2HCl) has strong ability to immobilize Protein G molecules on the electrode surface and the immobilized Protein G provides an orientation-controlled binding of antibodies. A monolayer of propanethiol was firstly self-assembled on the gold electrode surface, and a copper monolayer was deposited via UPD on the propanethiol modified electrode. Propanethiol monolayer helps to stabilize the copper monolayer by pushing the formation and stripping potentials of the copper UPD monolayer outside the potential range in which copper monolayer can be damaged easily by oxygen in air. A droplet DTBP-Protein G was then applied on the modified electrode surface followed by the immobilization of estradiol antibody. Finally, a competitive immunoassay was conducted between estradiol-BSA (bovine serum albumin) conjugate and free estradiol for the limited binding sites of estradiol antibody. Square wave voltammetry (SWV) was employed to monitor the electrochemical reduction current of ferrocenemethanol and the SWV current decreased with the increase of estradiol-BSA conjugate concentration at the Immunosensor surface. Calibration of Immunosensors in waste water samples spiked with 17β-estradiol yielded a linear response up to ≈ 2200 pg mL(-1), a sensitivity of 3.20 μA/pg mL(-1) and a detection limit of 12 pg mL(-1). The favorable characteristics of the Immunosensors such as high selectivity, sensitivity and low detection limit can be attributed to the Cu UPD|DTBP-Protein G scaffold.

  • Detection of cortisol at a gold nanoparticle|Protein G–DTBP-scaffold modified electrochemical Immunosensor
    The Analyst, 2011
    Co-Authors: Xiaoqiang Liu, Ruoxia Zhao, Wenling Mao, Heqing Feng, Xiuhua Liu, Danny K.y. Wong
    Abstract:

    An ultrasensitive electrochemical immmunosensor was demonstrated to be capable of detecting the hormone cortisol down to concentrations as low as 16 pg mL−1. In addition, the Immunosensor displayed a sensitivity of 1.6 μA pg−1 mL−1 and a linear range up to ∼2500 pg mL−1 of cortisol. This Immunosensor was constructed based on a Au nanoparticle|dimethyl 3,3′-dithiobispropionimidate·2HCl (DTBP)–Protein G scaffold-modified Au electrode. In this work, the Au nanoparticles were used to increase the electrochemically active surface area by 28% (with a standard deviation of 3%) to enhance the quantity of the Protein G scaffold on the electrode. Thiolation of Protein G by DTBP aided in avoiding the confirmation change of Protein G, while this Protein G–DTBP component offered an orientation-controlled immobilisation of the capture antibody on the Au electrode. In this Immunosensor, a monoclonal anti-cortisol capture antibody was optimally aligned by the scaffold before a competitive immunoassay between sample cortisol and a horseradish peroxidase-labelled cortisol conjugate was conducted. For quantitative analysis, square wave voltammetry was used to monitor the reduction current of benzoquinone produced from a horseradish peroxidase catalysed reaction. The improved analytical performance of our Immunosensor was attributed to the synergetic effect of Au nanoparticles and the Protein G–DTBP scaffold.

  • square wave voltammetry versus electrochemical impedance spectroscopy as a rapid detection technique at electrochemical Immunosensors
    Biosensors and Bioelectronics, 2010
    Co-Authors: Xiaoqiang Liu, Paul A Duckworth, Danny K.y. Wong
    Abstract:

    Abstract Square wave voltammetry (SWV) was compared to electrochemical impedance spectroscopy (EIS) in developing a label-free electrochemical Immunosensor for the hormone estradiol. The Immunosensor consists of a Au electrode anchored with a Au nanoparticle|thiolated Protein G-scaffold to facilitate immobilisation of an enhanced quantity of an almost uprightly aligned anti-estradiol capture antibody. Competitive immunoassays between an estradiol–bovine saline albumin complex and free estradiol in a sample were then promoted at the Immunosensor. Next, SWV and EIS of [Fe(CN) 6 ] 3−/4− were sequentially conducted at the Immunosensor. SWV yielded familiar peak-shaped voltammograms with the peak currents readily employable in establishing calibration. A dynamic range up to ∼1200 pg mL −1 and a detection limit of 18 pg mL −1 estradiol were achieved. In EIS, an electron transfer resistance estimated from the Nyquist plots was used in the calibration experiments. A comparable dynamic range up to ∼1000 pg mL −1 and a detection limit of 26 pg mL −1 estradiol were obtained. However, a significantly 10 times longer analysis time and substantial effort were required to complete the EIS determinations relative to SWV. Moreover, a large amount of EIS data involving phase angle was collected but ignored because they would not contribute any useful information to quantitative determination. Overall, SWV was determined to be a more rapid, efficient, effective and low cost detection technique than EIS at label-free electrochemical Immunosensors.

  • Picogram-detection of estradiol at an electrochemical Immunosensor with a gold nanoparticle|Protein G-(LC-SPDP)-scaffold.
    Talanta, 2008
    Co-Authors: Xiaoqiang Liu, Danny K.y. Wong
    Abstract:

    Abstract Low picograms of the hormone 17β-estradiol were detected at an electrochemical Immunosensor. This Immunosensor features a gold nanoparticle|Protein G-(LC-SPDP) 1 -scaffold, to which a monoclonal anti-estradiol capture antibody was immobilised to facilitate a competitive immunoassay between sample 17β-estradiol and a horseradish peroxidase-labelled 17β-estradiol conjugate. Upon constructing this molecular architecture on a disposable gold electrode in a flow cell, amperometry was conducted to monitor the reduction current of benzoquinone produced from a catalytic reaction of horseradish peroxidase. This current was then quantitatively related to 17β-estradiol present in a sample. Calibration of Immunosensors in blood serum samples spiked with 17β-estradiol yielded a linear response up to ∼1200 pg mL−1, a sensitivity of 0.61 μA/pg mL−1 and a detection limit of 6 pg mL−1. We attribute these favourable characteristics of the Immunosensors to the gold nanoparticle|Protein G-(LC-SPDP) scaffold, where the gold nanoparticles provided a large electrochemically active surface area that permits immobilisation of an enhanced quantity of all components of the molecular architecture, while the Protein G-(LC-SPDP) component aided in not only reducing steric hindrance when Protein G binds to the capture antibody, but also providing an orientation-controlled immobilisation of the capture antibody. Coupled with amperometric detection in a flow system, the Immunosensor exhibited excellent reproducibility.

  • An amperometric Immunosensor with a thiolated Protein G scaffold
    Electrochemistry Communications, 2008
    Co-Authors: Jeremy Fowler, Margaret C. Stuart, Danny K.y. Wong
    Abstract:

    The orientation of the analyte-specific capture antibody on the surface of electrochemical Immunosensors plays an important role on their overall performance. We have employed a self-assembled layer of Protein G that was thiolated with succinimidyl-6-[3′-(2-pyridyldithio)-propionamido] hexanoate for the orientation-controlled immobilisation of a capture antibody in a flow-type amperometric Immunosensor based on a two-site sandwich immunoassay. After establishing the formation of the thiolated Protein G layer on 1-mm screen printed electrodes, amperometric Immunosensors for the detection of the hormone, human chorionic gonadotrophin (hCG), were successfully constructed upon this scaffold. These sensors were characterised by a limit of detection (based on three times the standard deviation of the blank signal) of 175 IU l−1 and a linear response up to approximately 5000 IU l−1 of hCG.

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.

  • 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 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.

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

  • Enzyme modified peptide nanowire as label for the fabrication of electrochemical Immunosensor
    Sensors and Actuators B-chemical, 2014
    Co-Authors: Jianglin Zhang, Xiang Chen, Minghui Yang
    Abstract:

    Abstract Ferrocene (Fc) functionalized self-assembled peptide nanowire (Fc-PNW) was synthesized, functionalized and used as label for the fabrication of electrochemical Immunosensors to detect substance P (SP). To prepare the label, gold nanoparticles (AuNPs) were immobilized onto the Fc-PNW for the following adsorption of horseradish peroxidase (HRP) and secondary anti-SP antibody (Ab2, Fc-PNW-HRP-Ab2). The role of Fc-PNW in the electrochemical label was not only as supporting matrix for HRP and Ab2, but also as the mediator for HRP to enhance the sensitivity of HRP toward H2O2 detection. The Immunosensor was fabricated based on the traditional sandwich protocol with primary anti-SP antibody (Ab1) immobilized onto graphene surface. The catalytic current of HRP toward H2O2 in the presence of mediator Fc was used as signal of the Immunosensor. Different parameters, such as the weight ratio of HRP to Ab2 on the Fc-PNW and the antibody–antigen incubation time were optimized to improve the performance of the Immunosensor. The resulting Immunosensor has high sensitivity, wide linear range (0.01–50 ng/mL) and low detection limit (5 pg/mL).

  • Sensitive electrochemical Immunosensor for the detection of cancer biomarker using quantum dot functionalized graphene sheets as labels
    Sensors and Actuators B: Chemical, 2011
    Co-Authors: Minghui Yang, Alireza Javadi, Shaoqin Gong
    Abstract:

    Abstract Quantum dot (QD) functionalized graphene sheets (GS) were prepared and used as labels for the preparation of sandwich-type electrochemical Immunosensors for the detection of a cancer biomarker (i.e., prostate specific antigen (PSA)). The primary anti-PSA antibody was also immobilized onto the GS. The Immunosensor displayed a wide range of linear response (0.005–10 ng/mL), low detection limit (3 pg/mL), and good reproducibility, selectivity and stability. The Immunosensor was used to detect PSA in patient serum samples with satisfactory results. Thus, this unique Immunosensor may provide many applications in clinical diagnosis.

  • 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.

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

  • 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.

  • New amperometric and potentiometric Immunosensors based on gold nanoparticles/tris(2,2′-bipyridyl)cobalt(III) multilayer films for hepatitis B surface antigen determinations
    Biosensors and Bioelectronics, 2005
    Co-Authors: Dianping Tang, Jianyuan Dai, Ruo Yuan, Yaqin Chai, Xia Zhong
    Abstract:

    Abstract Two generic, fast, sensitive and novel electrochemical Immunosensors have been developed. Initially, a layer of plasma-polymerized Nafion film (PPF) was deposited on the platinum electrode surface, then positively charged tris(2,2′-bipyridyl)cobalt(III) (Co(bpy) 3 3+ ) and negatively charged gold nanoparticles were assembled on the PPF-modified Pt electrode by layer-by-layer technique. Finally, hepatitis B surface antibody (HBsAb) was electrostatically adsorbed on the gold nanoparticles surface. Electrochemical behavior of the {Au/Co(bpy) 3 3+ } n multilayer film-modified electrodes was studied. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS) were adopted to monitor the regular growth of the multilayer films. The performance and factors influencing the performance of the resulting Immunosensors were studied in detail. The multilayer film-modified Immunosensor was used for hepatitis B surface antigen (HBsAg) determination via the amperometric and potentiometric Immunosensor systems, and both systems provided the same linear ranges from 0.05 to 4.5 μg/mL with different detection limits for the amperometric system 0.005 μg/mL and for the potentiometric system 0.015 μg/mL. The Immunosensors were used to analyse HBsAg in human serum samples. Analytical results of clinical samples show that the developed immunoassay is comparable with the enzyme-linked immunosorbent assays (ELISAs) method, implying a promising alternative approach for detecting HBsAg in the clinical diagnosis. In addition, the multilayer films also showed better stability for 1 month at least.

  • Potentiometric Immunosensor Based on Immobilization of Hepatitis B Surface Antibody on Platinum Electrode Modified Silver Colloids and Polyvinyl Butyral as Matrixes
    Electroanalysis, 2005
    Co-Authors: Dianping Tang, Jianyuan Dai, Ruo Yuan, Yaqin Chai, Linyan Zhang, Yan Liu, Xia Zhong
    Abstract:

    A highly sensitive Immunosensor based on immobilization of hepatitis B surface antibody (HBsAb) on platinum electrode (Pt) modified silver colloids and polyvinyl butyral (PVB) as matrixes has been developed for potentiometric immunoanalysis to detect hepatitis B surface antigen (HBsAg) in this study. HBsAb molecules were immobilized successfully on nanometer-sized silver colloid particles associated with polyvinyl butyral on a platinum electrode surface. The modification procedure was electrochemically monitored by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The HBsAb-silver-PVB-modified electrode exhibited direct electrochemical behavior toward HBsAg. The factors influencing the performance of the resulting Immunosensor were studied in detail. More than 94.7% of the results of human serum samples obtained by this method were in agreement with those obtained by enzyme-linked immunosorbent assays (ELISAs). The resulting Immunosensor exhibited a sigmoid curve with log HBsAg concentration, high sensitivity (39.8 mV/decade), wide linear range from 16.0 to 800 ng mL−1 with a detection limit of 3.6 ng mL−1, fast potentiometric response ( 4 months). The response mechanism of the Immunosensors was also studied with AC impedance techniques.