Immobilization Of Glucose Oxidase On Fe₃O₄-SiO₂ Nano-Composite And Its Application

Biosensing material is an important part of fiber optic biosensor. The research on optical biosensing materials is the key technology to develop the fiber optic biosensors with good properties. The reported sensing materials for fiber optic biosensor based on enzyme catalysis usually consist of two parts, optical sensing part and catalysis part. If these two parts are combined into one using an appropriate method to form the opitcal complex sensing materials, the response rate and detecting precision of the sensor can be improved greatly, and the sensor micromation will probably be realized. This kind of work is very important to the application of fiber optic sensor based on enzyme catalysis. The detection of glucose concentration in blood is of great significance for human health monitoring and early diagnosis of diseases. Among the various detecting methods, fiber optic biosensor based on enzyme catalysis is an effective means. Therefore, the research on this kind of fiber optic biosensor is of great theory and application importance.In this thesis, the magnetic Fe3O4-SiO2 nanoparticle composite (FSNPs) was successfully prepared and used as the carrier for glucose oxidase immobilization, and the immobilized glucose oxidase with good properties has been obtained. The optical complex biosensing materials containing both immobilized enzyme and fluorescent indicator were prepared. The fiber optic glucose sensor based on catalytic enzyme was designed and constructed, and the preliminary study on its properties has been performed.The work of this paper includes mainly three parts as followed:(1) Fe3O4 nanoparticle was prepared by co-precipitation method with size of 15nm. A good morphology and single size FSNPs was prepared by sol-gel method. The composite were characterized by TEM and Model 4HF VSM. The nanoparticle composite with an average size of 60-80nm is almost superparamagnetic and has promising biocompatibility.(2) The glucose oxidase was immobilized on the surface of the FSNPs by crosslinking method. The effects of silane reagent APTS, glutaraldehyde concentration, the pH on crosslinking process and the amount of glucose oxidase on the activity of immobilized enzyme were investigated. After immobilization, the optimum pH, temperature and Km of immobilized enzyme catalyse glucose were 7,50℃and 34.9 respectively. The immobilized glucose oxidase has a better stabilities in thermal, storage and operation.(3) The optical complex biosensing materials containing both immobilized enzyme and fluorescent indicator were prepared. The fiber optic glucose sensor test system was designed and fabricated, the preliminary research results show that its detecting range is 100～600 mg/dl and its response time is about 15s.