Study On The Electrochemistry Biosensor Based On Ferrocene As Electron Transfer Mediator

The biosensor is a novel analytical measurement, which has been a most burgeoning and one of the most flourish research realms in the electrochemistry and electronanlytic chemistry since it was develop in the middle of 70'. The advantages of the biosensor including their inexpensive instrumentation, simple-design, high-sensitivity, low-cost and fair selectivity attract substantial research efforts directed to the developments of some new electrochemical biosensors and have been used in clinical, environmental control, and food quality control, etc. In thesis, the second genetation amperometric glucose biosensor and hydrogen peroxide biosensor is prepatation by conducting electron mediator. The main works are included as follows:1. A novel amperometric biosensor for glucose was developed by entrapping glucose oxidase (GOD) in a chitosan composite doped with ferrocene monocarboxylic acid-aminated silica nanoparticles conjugate (FMC-ASNPs) and multiwall carbon nanotubes (MWNTs). The entrapped FMC-ASNPs conjugate performed excellent redox electrochemistry and the presence of MWNTs improved the conductivity of the composite film. This matrix showed a biocompatible microenvironment for retaining the native activity of the entrapped GOD and was in favor of the accessibility of substrate to the active site of GOD, thus the affinity to substrates is improved greatly. Under optimal conditions this biosensor was able to detect glucose with a detection limit of 10μM (S/N = 3) in the linear range of 0.04 to 6.5mM. The proximity of these three components FMC-ASNPs, MWNTs and GOD enhanced the electron transfer between the film and electrode. This composite film can be extended to immobilize other enzymes and biomolecules, which will greatly facilitate the development of biosensors and other bioelectrochemical devices.2. The Au@S(CH₂)₆Fc modified electrode was prepared by self-assembly with HS(CH₂)₆Fc which is synthesized by ourselves. The preparation and the electrochemical characteristics of Au@S(CH₂)₆Fc modified electrode have been investigated. The experimental results show that the Au@S(CH₂)₆Fc modified electrode has strong catalytic effect towards the electrochemical oxidation of dopamine (DA). The linearity of DA in the range of 1.0×10^-6-2.6×10^-3 mol/L with detection limit of 3.0×10^-7 mol/L and the correlation coefficient of 0.9997 are obtained from the current responses of DA. The resulting modified electrode under optimal conditions shows high sensitivity, long-term operational stability, and fast response time and wide-range detection. And this method can be used for the determination of dopamine in real sample.3. A kind of nanocomposites with good dispersion in water was prepared through Schiff base reaction of ferrocenecarboxaldehyde(Fc-CHO) and functional multiwalled carbon nanotubes (MWNTs) for electric communication between glucose oxidase and electrode. The nanocomposites(MWNTs-Fc) is characterized by using FT-IR spectroscopy. With the aid of chitosan, glucose oxidase and MWNTs-Fc was t immobilized on the electrode to form a reagentless amperometric sensor for glucose. The presence of both Fc-CHO and MWNTs as conductor enhanced greatly the enzymatic response to the oxidation of glucose. The novel biosensor exhibited fast response towards glucose with a detection limit of 3. 0×10^-6 mol/L (S/N = 3) and the linear range is 1. 2×10^-5～3.8×10^-3mol/L (r=0.9995).