Studies Of Electrochemical Biosensing Techniques Based On Tyramide Oxidation Deposition

Biosensors play a significant role in clinical diagnosis, food and environment monitoring as well as biochemical attack warning. It is one of the frontier areas in analytical chemistry. The primary subject of biosensing studies is the immobilization of biomolecules at sensing interface and the signaling of specific events of biological interaction. Seeking for novel materials and techniques to develop biosensors with imrpoved selectivity and enhanced sensitivity has been a subject of keen interest in analytical chemistry. Tthe present thesis focuses on the following three aspects:1. The development of electrochemical biosensors, especially immunosensors was reviewed, which introduced the concepts and fundamental principles of biosensors. According to the difference of transducers, immunosensors were classified into several types, and the working principles and the characteristics of electrochemical immunosensors of different types were exposited. We also deals in details with recent progresses and applications of enzyme-linked electrochemical immunosensors in analytical chemistry.2. An amperometric glucose biosensor was developed based on immobilization of glucose oxidase (GOD) on the electrochemically polymerized polytyramine (PTY) film and the overoxidised polypyrrole (OPPY) film on carbon paste electrode (CPE). The platinum-electrodeposited CPE provides a large apparent surface area for sensitive detection of H2O2. A polytyramine film was electrochemically obtained for the immomilization of GOD and an overoxidised polypyrrole film was used for eliminating the interferences from other electroactive materials. The sensor show a linear response toβ-D-glucose over a concentration range of 1×10^-5～1.8×10-2 mol/L,and the detection limit was 5×10^-6mol/L. The response time of the sensor was less than 10 s and the lifetime was over 2 months. Due to the permselective characteristics of the OPPY film , the effects of electroactive interferents such as ascorbic acid and uric acid and fructose could be significantly reduced.3. It was shown that gold nano-particles (colloid Au) could be used as a platform to immobilize antibodies by adsorption. Via a sandwich immunossary format with goat-anti-humanIgG labled Horseradish peroxidase(HRP) as the second antibody, a...