以乙型肝炎表面抗原和乙型肝炎表面抗体为模型免疫蛋白，对传染病的诊断技术进行了研究。利用吸附在铂电极表面Nafion膜中负电性的磺酸基与乙型肝炎表面抗体（HBsAb）分子中的氨基阳离子之间的静电作用实现抗体的结合，同时通过纳米金（Au）增加抗体的固定量，以及聚乙烯醇缩丁醛（PVB）薄膜的笼效应把乙型肝炎表面抗体和纳米金固定在铂电极上，从而制得高灵敏、高稳定电位型免疫传感器（PVB/Au/HBsAb/Nafion/Pt）通过循环伏安法和交流阻抗技术考察了电极表面的电学特性，并对该免疫传感器的性能进行了详细的研究。该免疫传感器具有制备简单、灵敏度高、线性范围宽、响应时间快（<3min）、稳定性好、寿命长（>4个月）、选择性等特点，将其用于病人的血清样品分析，其结果令人满意。

A novel glucose biosensor fabricated by self-assembling of double-layer 2d-network of (3-mercaptopropyl)-trimethoxysilane (MPS), gold nanoparticles and glucose oxidase (GOD) has been studied on gold substrate. A clean gold electrode was first immersed in solution of MPS in ethanol to produce a self-assembled monolayer, and then the silane units were polymerized into a 2d-network by dipping into aqueous NaOH. The second silane layer was then formed by immersion back into the MPS solution overnight, and then the gold nanoparticles were chemisorbed onto the thiol groups of the second silane layer. Finally, GODx was adsorbed onto the surface of the gold nanoparticles. The modified process was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Analytical parameters, such as pH and temperature, were also studied.With the aid of Co (byp) 33+ as a mediator in the solution, the electrode displayed excellent electrocatalytical response to the glucose. The peak currents were proportional to the glucose concentration in the range of 4.00×10−10 to 5.28×10−8M with a correlation coefficient of 0.99. Moreover, such a modified electrode exhibits a good stability and sensitivity. 0925-4005/$ -see front matter.

In this paper, two technologies named as the self-assembled technique and the opposite-charged adsorption are combined for a novel immobilization of diphtheria antibody (anti-Diph) molecules applied to an immunosensor for detecting diphtheria antigen (Diph). Anti-Diph was immobilized successfully on nanometer-sized Au colloid particles associated with polyvinyl butyral on a platinum electrode surface, and was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized anti-diphtheria was shown to keep its biological activity well and exhibited direct electrochemical behavior toward Diph. The factors influencing the performance of the resulting immunosensor were studied in detail. The resulting immunosensor exhibited fast potentiometric response (<3min) and the linear range was from 24 to 1280ngmL−1 with a detection limit of 7.8ngmL−1. Moreover, the studied immunosensor exhibited high sensitivity and long-term stability. The response mechanism of immuosensors was also preliminarily studied using AC impedance.

A novel potentiometric immunosensor for detection of hepatitis B surface antigen (HBsAg) has been developed by means of self-assembly (SA) and opposite-charged adsorption (OCA) techniques to immobilize hepatitis B surface antibody (HBsAb) on a platinum electrode. A cleaned platinum electrode was first pretreated in the presence of 10% HNO3 and 2.5% K2CrO4 solution and held at-1.5V (vs SCE) for 1 min to make it negatively charged and then immersed in a mixing solution containing hepatitis B surface antibody, colloidal gold (Au), and polyvinyl butyral (PVB). Finally, HBsAb was successfully immobilized onto the surface of the negatively charged platinum electrode modified nanosized gold and PVB sol-gel matrixes. The modified procedure was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized hepatitis B surface antibody exhibited direct electrochemical behavior toward hepatitis B surface antigen (HBsAg). The performance and factors influencing the performance of the resulting immunosensor were studied in detail. More than 95.7% of the results of the human serum samples obtained by this method were in agreement with those obtained by enzyme-linked immunosorbent assays (ELISAs). The resulting immunosensor exhibited fast potentiometric response (<3min) to HBsAg. The detection limit of the immunosensor was 2.3 ng‚mL-1, and the linear range was from 8 to 1280ng‚mL-1. Moreover, the studied immunosensor exhibited high sensitivity, good reproducibility, and long-term stability (>6months).

A conventional three-electrode system is fabricated to prepare a novel modified amperometric immunosensor for rapid determination of a-1-fetoprotein (AFP) in human serum. The immunosensor was prepared by entrapping thionine (Thi) into Nafion (Nf) to form a composite Thi/Nf membrane, which yield an interface containing amine groups to assemble gold nanoparticles (nano-Au) layer for immobilization of a-1-fetoprotein antibody (anti-AFP). The stepwise self-assemble procedure of the immunosensor was further characterized by means of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The factors influencing the performance of the resulting immunosensor were studied in detail. After the immunosensor was incubated with AFP at 37C for 10min, the CVs current decreased linearly in concentration ranges of AFP from 5.0 to 200.0ng/mL with a detection limit of 2.4ng/mL. Moreover, the studied immunosensor exhibited good accuracy, high sensitivity and long-term stability (>3months). The proposed method is economical and ecient, making it potentially attractive for clinical immunoassays.

In this paper, electrochemical behavior of a diphtheria immunosensor modified with nano-size conductor and semiconductor, as a mode of silica/gold/silver nanoparticles, has been investigated. Potentiometric immunosensor, cyclic voltammetry, and electrochemical impedance techniques were used to investigate the immobilization of diphtheria antibody on silica/gold/silver colloids. In the impedance spectroscopic study, an obvious difference of the electron transfer resistance between the silica-colloid modified electrode and the gold/silver-colloid modified electrodes was observed. The cyclic voltammogram tends to be more irreversible on silica colloids. Subsequently, using the silica colloid-modified immunosensor by potentiometry as a mode, it is found that the resulting immunosensor exhibited fast potentiometric response (<3min), high sensitivity and good reproducibility. Moreover, analytical results of several specimens obtained using the silica colloid-modified immunosensor are in satisfactory agreement with those given by the ELISA method, implying a promising alternative approach for detecting diphtheria antigen in the clinical diagnosis.

A novel potentiometric immunosensor for detection of Japanese B encephalitis vaccine was developed by immobilizing antiserum of Japanese B encephalitis on nano-Au/polymerized o-phenylenediamine (o-PDA) film on the platinum (Pt) electrode. The performance and factors influencing the performance of the resulting immunosensor were studied. The immunosensor showed a specific response to Japanese B encephalitis vaccine in the range 1.1×10 8 to 2.0×10-6lgpfu/ml (plaque forming unit) with a detection limit of 6×10 9 lgpfu/ml. The correlation coeffcient is 0.9986. The incubation time, incubation temperature, pH, reproducibility and stability of the immunosensor were also studied. The present work supplied a promising test method for biological products.

A novel selective thiocyanate PVC membrane electrode based on bis-bebzoin-semitriethylenetetraamine binuclear copper (II)[Cu(II)2-BBSTA] as neutral carrier is reported, which displays an anti-Hofmeister selectivity sequence in following order: SCN>ClO4>I>Sal>SO23>NO.3>H2PO4>Cl>NO.2>SO24. The electrode exhibits Nernstian potential linear range to thiocyanate from 1.0 10 1 to 9.0 10 7mol/l with a detection limit 7.0 10 7mol/l and a slope of) 57.0mV/decade in pH 5.0 of phosphorate buer solution at 25C. The response mechanism is discussed in view of the AC impedance technique and the UV spectroscopy technique. From comparison of potentiometric response characteristics between the binuclear metallic complex copper (II) [Cu (II) 2-BBSTA] and mononuclear copper (II) metallic complex [Cu (II)-BBSDA], an enhanced response towards thiocyanate from the electrode based on binuclear metallic complex copper (II) [Cu (II) 2-BBSTA] was observed. The electrode based on binuclear copper (II) compound was used to determine the thiocyanate content in waste water with satisfactory results.

Hepatitis B surface antibody (HBsAb) was immobilized to the surface of platinum electrode modified with colloidal gold and polyvinyl butyral (PVB) as matrices to detect hepatitis B surface antigen (HBsAg) via electrochemical impedance spectroscopy (EIS). The electrochemical measurements of cyclic voltammetry and impedance spectroscopy showed that K4 [Fe (CN) 6]/K3 [Fe (CN) 6] reactions on the platinum electrode surface were blocked due to the procedures of self-assembly of HBsAb-Au-PVB. The binding of a specific HBsAb to HBsAg recognition layer could be detected by measurements of the impedance change. A new strategy was introduced for improving the sensitivity of impedance measurements via the large specific surface area and high surface free energy of Au nanoparticles and the encapsulated effect of polyvinyl butyral. The results showed that this strategy caused dramatic improvement of the detection sensitivity of HBsAg and had good linear response to detect HBsAg in the range of 20-160 ngml 1 with a detection limit of 7.8ngml 1. Moreover, the studied immunosensor exhibited high sensitivity and long-term stability.

A novel indicator free DNA biosensors fabricated by self-assembling of bilayer two-dimensional 3-mercaptopropyltrimethoxysilane (B2dMPTS), gold nanoparticles and oligonucleotide has been studied on gold substrate. The thiol groups of 3-mercaptopropyltrimethoxysilane (MPTS) serve as binding sites for the covalent attachment of MPTS to gold electrode surface. After hydrolysation and condensation, the polymerized monolayer, one-dimensional network of MPTS (1dMPTS) was combined together into a two-dimensional sol-gel network (2dMPTS). The second silane layer (B2dMPTS) was formed by immersing electrodes back into the MPTS solution overnight, and then the gold nanoparticles were chemisorbed onto the thiol groups of the second silane layer. Finally, the mercapto oligonucleotide was self-assembled onto the surface via the gold nanoparticles. Electrochemical impedance spectroscopy (EIS) was used to characterize the modified process. And we used the impedance spectroscopy as a platform for reagentless DNA sensing assay. The performance and factors influencing the performance of the resulting biosensor were studied in detail. The linear range of the biosensor was from 1.0×10−8 to 1.0×10−6M with a detection limit of 5.0 10−9M at 30. In addition, the experiment results indicate that oligonucleotide immobilized on this way exhibits a good sensitivity, selectivity, stability and a long-term maintenance of bioactivity.