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ABSTRACT: Interests in using nanoporous metals for biosensing applications have been increasing. Herein, nanotubular mesoporous PdCu (NM-PdCu) alloy is used to fabricate a novel label-free electrochemical immunosensor for cancer biomarker carcinoembryonic antigen (CEA). It operates through physisorption of anti-CEA on NM-PdCu and the mixture of sulfonated graphene sheets (HSO(3)-GS) and thionine (TH) functionalized glassy carbon electrode interface as the detection platform. In this study, chitosan (CS)-PdCu is bound very strongly to carcinoembryonic antibody (anti-CEA), because of the good electron conductivity, high surface area, and good biocompatibility. CS-PdCu is immobilized on electrodes by electrostatic interactions between the negatively charged sulfo group of HSO(3)-GS and the abundant positively charged amino groups of chitosan. TH acts as the redox probe. Under the optimized conditions, the electrochemical immunosensor exhibits a wide working range from 0.01 to 12 ng/mL with a low detection limit of 4.86 pg/mL. The accuracy, reproducibility, and stability of the immunosensor are acceptable. The assay is evaluated for real serum samples, receiving satisfactory results. The nanoporous metal materials-based immunoassay provides a promising approach in clinical application and thus represents a versatile detection method.
Biosensors & bioelectronics 04/2012; 36(1):6-11. · 5.43 Impact Factor
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ABSTRACT: A sandwich electrochemical immunosensor for the sensitive determination of alpha fetoprotein (AFP) has been fabricated. Prussian blue modified hydroxyapatite (PB@HAP) was firstly prepared and used as electrochemical label due to the wonderful conductivity and good biocompatibility of HAP. The results proved that the immunosensor fabricated using the label based on PB@HAP loaded with horse radish peroxidase (HRP) and secondary anti-AFP antibody (Ab(2)) (PB@HAP-HRP-Ab(2)) had high sensitivity, and the sensitivity of the label PB@HAP-HRP-Ab(2) was much higher than labels of PB@HAP-Ab(2), PB-HRP-Ab(2) and HAP-HRP-Ab(2). The mixture of graphene sheet (GS) and thionine (TH) was not only used to immobilize anti-AFP antibody (Ab(1)) but also took part in the signal amplification. The amperometric signal increased linearly with AFP concentration in the range of 0.02-8 ng/mL with a low detection limit of 9 pg/mL. The immunosensor had the advantages of high sensitivity, good selectivity and good stability, and was applied to the analysis of AFP in serum sample with satisfactory results. Due to the low-cost and easy synthesis of PB@HAP, the screen-printed electrodes could be used instead of the bare glass carbon electrode in order to achieve mass production. In addition, it had potential application in the detection of other tumor markers.
Biosensors & bioelectronics 07/2011; 28(1):112-6. · 5.43 Impact Factor
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ABSTRACT: Based on the inhibition effect of transferrin (Tf) on the reaction of the luminol-hydrogen peroxide (H(2)O(2)) chemiluminescence (CL) system, catalysed by meso-tetra-(3-methoxyl-4-hydroxyl) phenyl manganese porphyrin (MnP) as a mimetic enzyme of peroxides, a sensitive flow-injection CL method has been developed for the determination of Tf in an alkaline medium. The CL reaction was carefully investigated by examining the variations of reaction conditions. Under optimum conditions, the linear range for the determination of transferrin was 0.04-20.0 μg/mL and the detection limit was 1.62 ng/mL. This proposed method was sensitive, convenient and simple, and has been successfully applied to the determination of transferrin in a serum sample.
Luminescence 04/2011; 26(6):629-33. · 1.73 Impact Factor
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ABSTRACT: BRCAl is an anti-oncogene in women, who are genetically predisposed to breast and ovary cancer. The detection of BRCA1 can offer an opportunity to characterize the function of genetic features in breast and ovarian cancer and to screen breast or ovarian cancer patients. In this study, we designed a new label and fabricated a novel sandwich-type electrochemical immunoassay for the ultrasensitive detection of BRCAl. Horseradish peroxidase (HRP) was entrapped in the pores of amino-group functionalized SBA-15 and the secondary antibody (Ab₂) combined with SBA-15 by covalent bond. Ionic liquid (IL) was added into the mixed solution of SBA-15/HRP/Ab₂ and application of IL increased the electrochemical activity of HRP and promoted electron transport. The synergistic effect between IL, SBA-15, Ab₂ and HRP could retain the bioactivity of HRP and Ab₂. The sensitivity of the sandwich-type immunosensor using SBA-15/HRP/Ab₂/BMIM·BF₄ as labels for BRCA1 detection was much higher than that using either SBA-15/HRP/Ab₂ or SBA-15/Ab₂ as labels. Under optimal conditions, the electrochemical immunoassay exhibited a wide working range from 0.01 to 15 ng/mL with a detection limit of 4.86 pg/mL BRCA1. The precision, reproducibility, and stability of the immunoassay were acceptable.
Biomaterials 03/2011; 32(8):2117-23. · 7.40 Impact Factor
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ABSTRACT: A label-free amperometric immunosensor for fast and sensitive assay of human serum chorionic gonadotropin (hCG) is presented. hCG was immobilized on nanoporous gold (NPG) foils and using hydroquinone (HQ) redox species as indicator. The variation of amperometric response to the concentration of hCG, the target antigen, was evaluated by cyclic voltammetry in phosphate-buffered solution. Taking advantage of dual-amplification effects of the NPG foils and graphene sheets (GSs), the immunosensor exhibited a specific response to hCG in the range of 0.5-40.00 ng ml(-1) with a detection limit of 0.034 ng ml(-1) under optimal conditions. It was demonstrated that our proposed method possesses good accuracy, acceptable precision, and reproducibility. The NPG showed a better sensitizing effect and stability as immobilization matrices.
Analytical Biochemistry 03/2011; 414(2):196-201. · 3.00 Impact Factor
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ABSTRACT: Nanoporous gold (NPG) film modified electrode for the construction of novel label-free electrochemical immunosensor for ultrasensitive detection of cancer biomarker prostate specific antigen (PSA) is described. Due to its high conductivity, large surface area, and good biocompatibility, NPG film modified electrode was used for the adsorption of anti-PSA antibody (Ab). The sensing signal is based on the monitoring of the electrode's current response towards K(3)Fe(CN)(6), which is extremely sensitive to the formation of immunocomplex within the nanoporous film. Under optimum conditions, the amperometric signal decreases linearly with PSA concentration (0.05-26 ng/mL), resulting in a low limit of detection (3 pg/mL). We demonstrated the application of the novel immunosensor for the detection of PSA in real sample with satisfactory results.
Biosensors & bioelectronics 02/2011; 26(8):3714-8. · 5.43 Impact Factor
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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.
Biosensors & bioelectronics 02/2011; 26(8):3590-5. · 5.43 Impact Factor
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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 (Ab2). The resulting nanoparticles, Au-MSN-HRP-Ab2 were used as labels for immunosensors to detect norethisterone antigen. A sandwich-type protocol was used to prepare the immunosensor with the primary antibody (Ab1) immobilized onto thionine (TH) and graphene sheet (GS) modified glassy carbon electrode surface. The sensitivity of the sandwich-type immunosensor using Au-MSN-HRP-Ab2 as labels for norethisterone antigen detection was much higher than that using either Au-MSN-Ab2 or MSN-HRP-Ab2 as labels. Within norethisterone concentration range (0.01-10 ng/mL), a linear calibration plot (Y=0.55671+8.27101X, 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.
Biosensors & bioelectronics 10/2010; 26(2):723-9. · 5.43 Impact Factor
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ABSTRACT: Experiments indicated that protein can enhance the fluorescence of the 4-chlorosulfo-(2'-hydroxylophenylazo)-rhodanine-Ti(IV) complex [ClSARP-Ti(IV)] in the presence of bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) microemulsion. Based on this, a sensitive and reproducible fluorometric method for the determination of micro amount protein was developed. The calibration curves of four proteins were given. Under the optimum experimental conditions, the enhanced fluorescence intensity of the system was in proportional to the concentration of protein in the range of 0.1-11 microg mL(-1) for bovine serum albumin (BSA), 1.0-10 microg mL(-1) for human serum albumin (HSA), 1.0-50 microg mL(-1) for ovalbumin (Ova) and 2.5-18 microg mL(-1) for gamma-globulins (gamma-G). Their detection limits were 0.070, 0.071, 0.33 and 0.22 microg mL(-1), respectively. The ClSARP-Ti(IV) complex as a spectral probe can be used to the determination of protein in milk powder and oatmeal yielding with satisfactory results. Therefore, the proposed method is one of the most sensitive methods available. In addition, the interaction mechanism of this system is studied by multi-techniques.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2009; 72(5):1047-53. · 2.10 Impact Factor
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ABSTRACT: In this study, amino group modified mesoporous silica nanoparticles (MSN) were prepared and used to immobilize both platinum nanoparticles (PtNP) and glucose oxidase (GOx). The prepared MSN–PtNP demonstrated high stability and reactivity for catalyzing H2O2 electro-reduction, mainly due to the large amount of PtNP immobilized, the high surface area of these catalysts and the unique nanostructures formed through the synthetic route. Working at −0.2 V, the linear range in response to H2O2 by the prepared MSN–PtNP can be 5 × 10−7 to 6 × 10−2 mol L−1. After immobilizing GOx onto MSN–PtNP, the resulting MSN–PtNP–GOx was capable of interference-free determination of glucose with the linear range as wide as 1 × 10−6 to 2.6 × 10−2 mol L−1. Furthermore, the fabricated glucose biosensor can offer significant advantages compared with its conventional counterparts, typically like the high sensitivity, good reproducibility and stability, and rapid response ability as well. The fabricated glucose biosensor demonstrated its potential in clinical applications, so as to enable the determination of glucose in real serum samples.
Electrochimica Acta. 56(7):2960-2965.
