Synthesis And Properties Of Redox Copolymer With Ferrocene Groups

The development of biosensor haven experienced 3 generation roughly along with the advance of science and technology and constantly endeavour of researcher in the field of biosensor. Above changes will contribute to obtain modified electrode with excellent stability, high electron transfer efficiency and to enlarge the application domain of modified electrode in the field of biomedical, environment monitoring, agricultural products detection and so on. Development of redox copolymers are almost copolymer of vinylferrocene on count of the excellent electronic properties and low redox potential approximately 0.4V(vs. Ag/Ag Cl) of ferrocene. However, the hydrophilicity of above copolymers is poor due to these copolymers contain large hydrophobic chain segments. Electrode modified with hydrophobic polymeric mediator cannot contribute to increase the amount of analyses partitioned into the electrode. Along with above changes, the amount of analyses oxidized by enzyme in enzyme electrode and catalytic current were also decreased. Therefore, enzyme electrode modified with hydrophobic polymeric mediator has a low detection limit.The properties of free radical polymerization of vinylferrocene and the main influence factors of electrode modified with vinylferrocene copolymer are described in this paper. Starting from the structure of polymeric mediator and the defect of the third generation enzyme biosensor, three kinds of water-soluble and redox-active copolymer of vinylferrocene with ferrocene group, water-soluble acrylamide and glycidyl methacrylate or dimethylaminoethyl methacrylate or dimethyl aminopropyl methacrylamide contained special group that can reacted with enzyme forming chemical band were synthesized by free radical polymerization. The introduction of aforementioned special group will contribute to increase the electron transfer efficiency and reduce the loss of enzyme of modified electrode. Vinylferrocene will endow polymer chain segments with ferrocene groups that can realize electron transfer between enzyme’s active centre and electrode surface by collide with each other. Water-soluble and flexible copolymer will be obtained by introduce the acrylamide constitutional unit. The above properties of copolymer will contribute to increase the detection limit, electron transfer efficiency, electron transfer rate of modified electrode and realize direct electron transfer between enzyme’s active centre and electrode surface. Glass-transition temperature, chemical composition, protonation and magnetic and electrochemical properties of copolymer were investigated by Differential Scanning Calorimeter, Fourier Infrared Spectrometer, Nuclear Magnetic Resonance Spectrometer, Physical Property Measurement System, Ultraviolet and Visible Spectrophotometer and Electrochemical Work Station. Protonation of copolymer bearing tertiary amino groups will give the copolymer positive charge at p H around neutral. Therefore, copolymer could have electrostatic interaction with glucose enzymes and hence, this change makes the distance between active centre of enzyme and electrode surface shorter. Electrochemical properties of copolymer present excellent oxidation-reduction reversibility and realize the reversible electron transfer between copolymer and electrode. In addition, lower diffusion coefficient of copolymer in solution can help to obtain modified electrode with excellent stability. The low diffusion coefficient of copolymer implies that direct electron transfer between enzyme’s active centre and electrode relayed on the electron hopping of neighboring ferrocenyl groups and the electron transfer between polymeric mediator and electrode rather than the diffusion of copolymer.