Study On Fiber Optic Biosensors Based On The Catalysis Of Immobilized Enzyme And Mimic Enzyme

The detection of biomass in the human body and the pollutants in the environment is of great significance. Diabetes mellitus is the most common endocrine disorder of carbohydrate metabolism, and the detection of glucose concentration in the blood is very important to the diagnosis of pre-diabetes or diabetes.2-chlorophenol (2-CP) is a kind of very toxic substance among the pollutants in the environment, and it is widespread and difficult to degrade. Therefore, the detection of2-CP concentration is of crucial importance to environmental protection and human health.Fiber optic biosensors have many advantages, such as small diameter probe, huge information transmission capacity, low energy consumption, fast response, low-cost, strong anti-interference ability and possibility of real-time and online monitoring, which provide an effective way for the detection of glucose and2-CP. In recent years, the research of fiber optic biosensors based on enzyme catalysis has been studied all over the world.Immobilized enzyme can improve the stability of enzyme greatly. Compared with nature enzyme, mimic enzyme have the advantages of higher stability, easy preparation and lower cost, which provides the bases for the application of fiber optic biosensors. In this thesis, two kinds of fiber optic biosensors based on the enzymatic catalysis were studied. We prepared a kind of sol-gel optical complex biosensing film which embedded both immobilized GOD on SiO2nanoparticle and fluorescence indicator Ru(byp)3Cl2. And we studied the performance of the fiber optic glucose sensor based on the biosensing film. The fiber optic2-CP sensor was constructed based on the TNFe(II)Pc catalyzed aerobic reaction. The lock-in amplifier technique was used to evaluate the performance of this sensor.In this thesis, the investigations have been performed in the following aspects.(1) The glucose oxidase was immobilized on the SiO2nanoparticles. The sol-gel optical complex biosensing film containing both immobilized GOD and fluorescence indicator Ru(bpy)3Cl2was prepared by sol-gel method and using DDS, TEOS, hydrochloric acid, PEG400as raw materials, Ru(bpy)3Cl2as the fluorescent indicator. The effects of the DDS/TEOS ratios, reaction pH, PEG400dosage and drying conditions on the performance of the biosensing film were investigated. The biosensing film was also characterized by SEM, AMF and FTIR.(2) The fiber optic glucose sensor based on the sol-gel optical complex biosensing film was constructed. The characteristics of the sensor such as response time, standard curve, repeatability and long-term stability were studied. The results showed a good linear relationship between the relative phase delay (△(?)) and glucose concentration in its detection range of100to700mg/dL. The lower and upper detection limits of sensors were50mg/dL and700mg/dL, respectively. The response time of the sensor was15s, and the fiber optic glucose sensor showed good repeatability and long-term stability.(3) The fiber optic2-CP sensor was constructed based on the TNFe(II)Pc catalyzed2-CP oxidation. The fluorescence indicator Ru(byp)3Cl2was used as oxygen-sensitive material and immobilized into a cellulose acetate (CA) membrane. The characteristics of the sensor such as response time, standard curve, repeatability and long-term stability were investigated. The results show the good linear relationship between the relative phase delay (△(?)) of sensing membrane and2-CP concentration in its detection range of lxl0-6to7xl0-6mol/L and7xl0-6to lxl0-4mol/L. The detection limit of this sensor was1x10-6mol/L, and the response time of this sensor was five minutes. The fiber optic2-CP sensor showed good repeatability and long-term stability.