| Hepatitis B, an epidemic disease with greatest harms for human health caused by hepatitis B virus, is highly prevalent in our country. Hepatitis B virus, originated from sufferers and infectors, can be spread by blood, sex-contact and closely contact. Diphtheria is an acute bacterial disease that usually affects the tonsils, throat, nose and/or skin, which can lead to breathing problems, heart failure, paralysis and sometimes death. Until now, some diagnostic procedures have been adapted to clinical analyses for hepatitis B and diphtheria. Most methods, unfortunately, require highly qualified personnel, tedious assay time, or sophisticated instrumentation. Therefore, exploring new, simple, and sensitive diagnostic methods with real-time output and a low cost is of considerable interest.The detection of the potentiometric immunoassay is based on the change in the potentiometric response before and after antigen-antibody reaction. Either antibodies or antigens in aqueous solution have a net electrical charge polarity, which is correlated to the isoelectric points of the species and the ionic composition of the solution. If antibodies combine with antigens, the electrical charge of the resulting complex will be different from that of antibody or antigen. If antibody is immobilized on the electrode, the surface charge of the electrode will depend on the net charge of the immobilized antibody. When antigen is present in the solution, the immunochemical reaction will take place at the interface with a resulting change of the surface charge. This change can be measured potentiometrically against the reference electrode immersed in the same solution. The shift of potentiometric response exhibits a linear dependence on the logarithm of the concentration of analytes. In this article, we have constructed several potentiometric immunosensors immobilized antigen/antibody onto substrate electrode based on nanoparticles/compound nanoparticles,polyvinyl butyral, sol-gel as matrixes. Analytical results of clinical samples show that the developed immunoassays are comparable with ELISAs and RIAs, implying a promising alternative approach in the clinical diagnosis. The detailed materials are shown as follows:The first part: Prediction-electrochemical immunosensor.The second part: Highly sensitive, long-term, renewable potentiometric immunosensors based on polyvinyl butyral and nanoparticles as matrixes have been developed. The biocomposite, which needs no additional curing, is directly used to construct the immunosensor at room temperature. The incorporation of BSA into the biocomposite reduces non-specific adsorption of immunosensors to a lower level. (1) In chapter 1, a highly sensitive potentiometric immunosensor for the diagnoses of epidemic diseases has been developed by means of self-assembly to immobilize hepatitis B surface antibody for the detection of hepatitis B surface antigen as a model. The modified procedure was further characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The influence and factors influencing the performance of resulting immunosensor were studied in detail. The resulting immunosensor exhibited high sensitivity, wide linear range, rapid potentiometric response (< 3 min) and long-term stability (> 4 months). 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 hepatitis B in the clinical diagnosis. (2) In chapter 2, a novel potentiometric immunosensor for the detection of diphtheria antigen has been developed by means of self-assembly to covalently immobilized diphtheria antibody on a glassy carbon electrode. The modification procedure was electrochemically monitored by characterization of the electrode surface. The performance and factors influencing the performance of the resulting immunosensor were studied in detail. The resulting immunosensor exhibited fast potentiometric response to Diph and the detection limit of the immunosensor was from 24 ng mL~-1 to 600 ngmL~-1 with correlation coefficient of 0.9979 and a detection limit of 5.2 ngmL~-1The third part: A novel potentiometric immunosensor for the detection of hepatitis B surface antigen has been developed by self-assembling gold nanoparticles to a thiol-containing sol-gel network. The self-assembling procedure was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Tests relating... |
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