Electrochemical Biosensor Based On The Different Oxidase Covalently Immobilized On The Conductiving Polythiophene Derivatives

Content:Biosensors have been extensively applied in clinical medicine, environmental monitoring, biopharmaceuticals, food safety and biofermentation etc, owing to their portability, specificity, high sensitivity, low cost, real-time in-vivo electrochemical detection and analysis. Recently, the electrochemical preparation of high performance of conducting polymers have attracted considerable attention in the fabrication of high enzyme activity and good stability of electrochemical enzyme biosensors. The polythiophene derivatives substituted with carboxy or hydroxy groups usually have desirable electrochemical activity, environmental stability and easy processibility, which were beneficial for the covalent immobilization of enzyme and the fabrication of high stability of electrochemical enzyme biosensors. However, polythiophene derivatives substituted with carboxy or hydroxy groups were usually electrosynthesized in traditional organic solvents, which were not beneficial for saving enzyme activity in electrochemical enzyme biosensors. Compared with traditional organic solvents, ionic liquids are a class of novel environmentally benign "green solvents", which could not only improve the performance of conductive polymer, but also improve enzyme activity. This paper mainly studied that poly(thiophene-3-acetic acid)(PTAA)/ascorbate oxidase (AO) biosensor and PTAA/glutamate oxidase (GO) biosensor were successfully fabricated by covalent immobilization of AO and GO on PTAA films electrosynthesized in ionic liquid1-Butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), respectively. In addition, poly(3,4-ethylenedioxythiophene methanol)(PEDOTM)-Multi-walled carbon nanotubes (MWCNTs)/glucose oxidase (GOx) biosensor was successfully fabricated by covalent immobilization of GOx on PEDOTM-MWCNTs composite films electrosynthesized in BmimPF6/water. Finally, the electrochemical behavior and parametric characterization as well as the performance of the fabricated biosensor were studied in detail.1PTAA films were synthesized electrochemically in ionic liquid BmimPF6. Electrochemical synthesis of PTAA films in different solvent system (acetonitrile and ionic liquid BmimPF6) were compared. The results exhibited electrochemical synthesis of PTAA films in BmimPF6improved biological compatibility of enzyme and reduced onset oxidation potential of TAA.2PTAA/AO biosensor was fabricated by covalent immobilization of AO on PTAA films electrosynthesized in BmimPF6in comparison with that electrosynthesized in acetonitrile. The fabricated biosensor based on PTAA films electrosynthesized in BmimPF6exhibited shorter response time, wider linear range, lower detection limit, better enzyme activity and bioaffinity, and better operational and storage stability in comparison with that in acetonitrile. 3PTAA/GO biosensor was successfully fabricated by covalent immobilization of GO on PTAA films. The electrochemical characterization and parameter optimization were studied in detail. The results exhibited the biosensor has a short response time, wide linear range, low detection limit, good enzyme activity and bioaffinity, remarkable sensitivity and good operational and storage stability.4PEDOTM-MWCNTs composite films were synthesized electrochemically by direct oxidation of EDOTM and MWCNTs in BmimPF6/water. The results exhibited the introduce of MWCNTs not only improved the ability of electron transfer of conducting polymers, but also improved the mechanical properties of conducting polymers.5PEDOTM-MWCNTs/GOx biosensor was successfully fabricated by covalent immobilization of GOx on PEDOTM-MWCNTs composite films. The results exhibited the biosensor has a short response time, wide linear range, low detection limit, good enzyme activity and bioaffinity, remarkable sensitivity and good operational and storage stability.