Preparation And Performance Of Nanoscale Complex Optical Biosensing Materials

The fiber optical sensing technology is multidisciplinary cross research fields including material science, information, life science, chemistry and physics. The preparation of fiber optic biosensing materials is one of the key technologies for the development of fiber optic biosensors with high performance. The fiber optic biosensing materials must have high sensitivity, high selectivity, fast response and long lifetime. The detection of glucose is very important in many fields including clinic diagnoses (especially for diabetes), basic medicine research and food industry. The current detection methods for glucose concentration are mainly instrument analysis and electrochemistry sensors, which have the disadvantages such as complex analysis process, low response and high cost. Fiber optic glucose sensor is an effective means for the glucose detection because of its advantages including high precision, fast response, simple operation process and low cost. Therefore, the study of fiber optic glucose sensor is of great importance.In this thesis, silica (SiO2) nanoparticles have been prepared. After the modification, the (SiO2) nanoparticles with amino groups on their surface have been obtained, which were used as the carriers for the immobilization of glucose oxidase (GOD). The optical complex biosensing material containing the immobilization GOD and fluorescent indicator was prepared, which has both the biological catalysis and optical sensitive properties. The fiber optic glucose sensor based on enzyme catalysis and fluorescence quenching was designed and fabricated and its properties have been studied.The main work in this thesis includes:(1) Using Stober method, SiO2 nanoparticles with an average diameter of 100nm were prepared and characterized by SEM. The surface of SiO2 nanoparticle was modified using APTES and GA to produce amino groups, which were used for GOD immobilization. The influence factors on immobilized enzyme activity such as APTES concentration, GA concentration, optimal enzyme concentration, pH value were studied.(2) The stability of immobilized GOD were studied and compared with free enzyme, which indicate that the immobilized GOD is more stable than free enzyme.(3) Using sol-gel method, a new kind of complex optical biosensing membrane was prepared which contains both immobilized GOD and Ru(bpy)3Cl2 indicator. With this biosensing membrane, the fiber optic glucose sensor based on enzymatic catalysis and fluorescence quenching was designed and fabricated. The detection was performed with lock-in technology. The properties of the sensor were studied, showing a good performance with the response time of 35s, glucose concentration detecting range of 100-500mg/dl and good linear relationship between the glucose concentration and phase delay.(4) The complex fluorescent sinica nanoparticles containing both GOD and fluorescent indicator have been prepared and their performance was studied, which will be a contribution to the development of new nanoscale complex optical biosensing materials.