Study Of Direct Electrochemistry On Carbon Fiber Ultramicroelectrode And Its Applications

Electrochemical biosensors combining the specific recognition of biomaterials with the magnification function of electrochemical determination have the advantages of high-sensitivity, nice-selectivity as well as easy miniaturization and automation. They can be applied to a wide range of analytical tasks, such as clinical diagnosis, bioassay, environmental monitoring and industrial analysis. The ultramicroelectrode possesses many advantages, such as rapid diffusing speed, high electrical current density, high signal-to-noise, accordingly, it can help to improve the detection sensitivity. So the ultramicroelectrode have become a powerful measurement tool to research the direct electron transfer of the big biological molecule (enzyme). This research is aimed to develop the direct electrochemistry behavior of redox proteins on the carbon fiber ultramicroelectrode (CFUME), to accelerate the direct electron transfer of the redox proteins by modifying a mediator layer on its surface, and to improve the selectivity of the electrochemical detection. The detailed materials are summarized as following:1. Considering the excellent electrochemical properties of ultramicroelectrode and the excellent film-forming ability and adhesion properties of chitosan, the plenty amounts of amino groups of chitosan film on the electrode surfaces facilitated the immobilization of horseradish peroxidase via glutaraldehyde covalent linkage. Employing Pt nanoparticles as an electron transfer accelerant, a mediatorless H2O2 miniaturized biosensor was fabricated. In the absence of mediator, a high sensitivity and selectivity of biosensor can be effectively obtained. The linear range of detection is 6.4×10-7 ~ 3.6×10-3 M. The results showed that the ultramicroelectrode is favorable to research the direct electron transfer of redox proteins (enzymes).2. Nano Au and chitoan nanocomposite was synthesized by intercalating nano Au into chitosan layers to obtain a stability nano Au layer on the electrode's surface. Its structure and electrochemical characteristics were studied, and the results showed that nano Au and chitoan nanocomposite possesses excellent ability of electron transfer. Hemoglobin was absorbed on the nanoAu and chitoan nanocomposite layer of the CFUME surface via the strong electrostatic interaction of nano Au, and a mediatorless biosensor was then otained. The result indicated that the nano Au monolayer is an appropriate interface for electron transfer. In the absence of mediator, the activity and...