Preparation Of Enzyme And DNA Electrochemical Sensors And The Immobilization Methodology Of Related Bio-materials

Electrochemical biosensors based on the specific recognition of biomaterials present some outstanding advantages including high sensitivity, nice selectivity, low cost, and the possibility of continuous monitoring of biological and synthetic processes. Typical applications include environmental monitoring and control, clinical diagnosis, chemical measurements in the agriculture, food and drug industries. In the design and fabrication of electrochemical biosensors, the development of a simple and effective strategy for the construction of sensitive membrane on the electrode is a crucial step. Aiming at the problems existed in immobilization technique of biosensors, this research developed a series of new immobilization matrixes to improve the perfomance and long-term stability of biosensors. The details are summarized as follows:1. In chapter 2, a urease sensor based on PVC-NH2 matrix pH-sensitive membrane has been proposed. A new method of urease immobilization based on the strong lection-glycoprotein was developed, Con A and urease were assembled layer by layer. The effects of experimental conditions and the response characteristics of sensor have been investigated in detail. The sensor showed a linear response to urea from 6.9×10-5 to 1.0×10-3 mol L-1 with a detection limit of 4.5×10-5mol L-1. The sensor was applied to the determination of urea in milk samples with satisfactory results.2. It was shown that the inhibition of urease by heavy-metal ions was irreversible. The activity of urease is hard to recover entirely with regeneration solution after contacting inhibitors for many times. For this reason, a renewable urease biosensor is highly desired. In chapter 3,a renewable potentiometric urease inhibition biosensor based on self-assembled gold nanoparticles has been developed for the determination of mercury ions. Gold nanoparticles were chemically adsorbed on the PVC-NH2 matrix membrane pH electrode surface containing N, N-Didecylaminomethylbenzene (DAMAB) as a neutral carrier and urease was then immobilized on the gold nanoparticles. The linear range of determination of Hg2+ was 0.09 to 1.99μmo L-1 with a detection limit of 0.05μmol L-1. The advantages of self-assembled immobilization are low detection limit, fast response and easy regeneration.3. In chapter 4,a new strategy to construct amperometric enzyme-linked immunosensor for human IgG assay based on ZnO/Chitosan composite as sensing platform has been described. This material, which combined the advantages of...