An effective and fast method for assay of micro-amounts of glucose was set up. A new technique for preparation of enzyme columns based on enzyme immobilization by sol-gel was investigated. Glucose oxidase(GOD) and horseradish peroxidase(HRP) mixed with SiO 2 nanoparticles and polyvinyl butyral(PVB) medium were immobilized on the surface of capillary tube, respectively. The experimental results show that nanoparticles can significantly enhance the catalytic activity of immobilized enzyme. Based on GOD column and HRP column, a liquid droplet sensor was developed for the determination of glucose solution. The effect of separated columns and mixed columns on the response of glucose sensor was investigated. The sensor showed a linear response in a range of 2-400 ng/mL with a detection limit of 0.3 ng/mL under the optimum conditions. The characteristics of the sensor including effect of flow-rate, pH and temperature were discussed.
A piezoelectric immunosensor has been developed for the detection of Hepatitis B surface antigen(HBsAg). Treatment of a Au electrode with cystamine solution results in cysteamine self assemble monolayers(SAMs). Using a bifunctional cross linker, glutaraldehyde, the antibody was immobilized on the electrode surface. The influence factors such as the reaction time of immunoreaction and the concentration of antibody etc. were investigated. Under the optimized experimental conditions, a series standard concentration of HBsAg solutions were analyzed in solution. The frequency shift was linear with the antigen mass concentration in the range of 0 2-12 0 μg/mL. The analysis results of two serum specimens showed that the positive serum and the negative serum could be distinguished easily. Glycine HCl solution(0 2 mol/L) was used for desorption of the bound antigen. The crystal could be regenerated nearly 8 times without detectable loss of activity.
