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Study On Amperometric Biosensors Based On New Organic-inorganic Hybrid Material

Posted on:2006-10-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:B YanFull Text:PDF
GTID:1118360212989357Subject:Environmental Science
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Biosensors are new analytical tools with the merits of selectivity, fast responding, low operation expense et al, and they have been applied into environment monitoring, clinical diagnosis, food quality control and military medicine. Sol-gel derived hybrid material have become one of the most appropriated enzymes immobilized matrix. In this thesis, a new sol-gel derived material has been composed and several glucose oxidase biosensors and a nitrate reductase biosensor have been fabricated. The electrochemistry characters of the biosensors have been studied, and lots of work has been done to enhance the performance of the glucose biosensors. The detailed work of this thesis has been set out as follows:A new graft polymer was composed by esterification reaction between Poly (vinyl alcohol) and mercaptoethylamine. Based on this graft polymer and sol-gel, a new organic-inorganic hybrid material had been obtained. The characters of the new graft polymer and hybrid material have been studied, and the parameters of hybrid material preparation have also been optimized.Based on this hybrid material, glucose oxidase was embedded and immobilized on surface of gold electrode to fabricate a new type of glucose biosensor. The enzymes embedded in the hybrid material showed high activity due to the great deal of hydroxide radical and hydrogen bonds of the hybrid material, The great deal mercapto group of the graft polymer can help the hybrid material membrane to be adsorbed onto gold surface tightly, so the biosensors based on this hybrid material have excellent stability. At the same time, the biosensor has many merits such as fast response, great response current and low detect limit.Based on this hybrid material and platinum electrode, a new type of glucose biosensor had been fabricated. This biosensor can work at a low potential (0.05V) so its antidisturbance performance was excellent.We have also fabricated a biosensor with the hybrid material and electrodeposited Prussian blue, this biosensor can work under–0.05V by reduction of the H2O2 produced by enzymes reaction. The low working potential can help to enhance the biosensor's interference immunity, so the biosensors have good practical value. After 21 days interval use, the response current dropped to 92% of its initial value. The response time of the biosensor was about 4s.To enhance the performance of the biosensors, silver nanoparticles and carbonnanotubes were added into the hybrid material. The result showed that the silver nanoparticles can extend the linearity range by 4 times and the carbon nanotubes can reduce the operating potential from 0.65V to 0.18V (vs SCE). The response time of the two biosensor were about 3.4s and 3s.Nitrate is a very important contamination of water, so the detection of nitrate by a fast and accurate method is of great value. In this thesis, the first amperometric nitrate reductases biosensor based on sol-gel derived hybrid material was fabricated. The nitrate biosensor showed good stability by 85.7% response current retained after 21 days. To our knowledge, this is the first amperometric nitrate reductase biosensor based on sol-gel materials.
Keywords/Search Tags:Mercapto-Poly(vinyl alcohol), Sol-gel, Organic/inorganic hybrid material, Biosensor, Glucose oxidase, Nitrate reductase
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