Studies On Electrochemical Biosensors Based On Plasma Polymerized Film And Opto-chemical PH Sensor Based On Covalent Immobilization Of Porphyrin

Immobilization methods of biomolecules are of the most importance for improving the performances of biosensors. The aim of the immobilization is to preserve inherent biological activity of biomolecules and firmly combine them with base electrode. Plasma polymerization technique is a useful tool for immobilizing biomolecules. Various kinds of organic monomer could be polymerized even if the monomer has no double bond in its structure. Moreover, plasma polymerized film could be formed on the surface of any substrates and are chemically and mechanically stable and having good biocompatibility. In this paper, a potentiometric acetylcholinesterase biosensor and two kinds of ampermetric hydrogen peroxide biosensors have been developed based on plasma polymerized film. Additionally, two kinds of porphyrins were synthesized and one has been used for fabricating opto-chemical sensor. Details are presented in this thesis as follows: (1) Plasma polymerized ethylenediamine films deposited on the pH-sensitive PVC membrane electrode by plasma discharge technique immobilized acetylcholinesterase by glutaraldehyde cross-linked. The potentiometric acetylcholinesterase biosensor prepared shows linear response over the concentration range of 5 10-6~1 10-2 mol/dm3 and the detection limit is 0.002 mmol/dm3. (2) A biosensor for hydrogen peroxide assay based on glassy-carbon electrode with plasma polymerized ethylenediamine films has been proposed. The biosensor provides a linear response to hydrogen peroxide over a concentration range of 5 10-7~1.1 10-3 mol/dm3 and a detection limit of 0.3 mol/dm3. (3) A procedure for fabrication a biosensor for hydrogen peroxide assay has been proposed based on the immobilization of horseradish peroxidase to a nano-scaled particulate gold which modified on glassy carbon electrode with plasma polymerized ethylenediamine films. The sensor exhibited a linear response to hydrogen peroxide in the range of 3.5 10-7~1.1 10-3 mol/dm3 with the detection limit of 0.2 mol/dm3 and longer lifetime than that of covalentty linked sensor. (4) A new porphyrin with methacrylate moiety was synthesized and was used for fabricating the opto-chemical pH sensor. The sensor could be used for pH determination in the pH range of 2.00-6.00 and the analytical results of water samples are in agreement with those determined by the conventional glass electrode. (5) A new porphyrin compound with carbazole moiety was synthesized. The fluorescence characteristics of the new compound have been studied.