Optimal Preparation Condition And Performance Of Optical Complex Biosensing Materials

The detection of biomass in human body (such as glucose) is of great significance for the early diagnosis of diseases and health monitoring. Fiber optic biosensor has many advantages, such as small diameter probe, huge information transmission capacity, low energy consumption, fast response time, low cost, easy to use, strong anti-interference ability and possibility of real-time and online monitoring, which provide an effective way for glucose detection. In recent years, the research of fiber optic biosensors based on enzyme catalysis has been a hot topic for the researchers all over the world.The research on high-performance optical biosensing materials is one of the key steps to develop high-performance fiber optic biosensor. In this thesis, two optical complex sensing materials, CA optical complex biosensing film and sol-gel optical complex biosensing film, were prepared. The fiber optical glucose sensor based on GOD catalysis and fluorescence quenching was fabricated and studied. The two optical complex biosensing films contain both photosensitizer and enzyme. After these two parts are combined into one using an appropriate method to form the optical complex sensing materials, the response rate and detecting precision of the sensor can be improved greatly, and it will also be beneficial to the sensor micromation.The main contents and results are in the following:(1) The optical complex biosensing film containing both glucose oxidase and fluorescence indicator has been prepared, using cellulose acetate as the carrier and ruthenium bipyridyl as the indicator. The cross-linking method was used to immobilize the enzyme and the embedding method was used to immobilize the indicator. The optimal enzyme immobilized conditions of the sensing film have been investigated and the results are as follows:the concentration of sodium periodate as 0.5 M and the reaction time as 0.5 h, those for ethanediamine as 0.04 M and 2.5 hours, those for GA as 1.5%(v/v) and 2 hours, those for GOD as 35 mg/mL and 21h, the pH of immobilized enzyme solution as 6.5.(2) The performances of CA optical complex biosensing film and the free enzyme such as optimal catalytic temperature, the optimal catalytic pH, thermal stability and storage stability, have been studied and compared. The optimal temperature and pH value for the catalytic properties of the sensing film are 40℃and 6.5, respectively. The fiber optical biosensor based on the biosensing film was fabricated. By using lock-in amplifier technology, the concentration of glucose was detected. The response time, standard curve, stability and repeatability of the sensor were studied. The results showed that the fiber optic glucose sensor has the linear detection range of 20～600 mg/dL, response time of less than 20s, and better long-term stability and repeatability. The lower and upper detection limits of sensors are 10 mg/dL and 600 mg/dL, repectively.(3) CoFe2CO4 nanoparticles were prepared by co-precipitation method. A good morphology and single size CoFe2O4/SiO2 magnetic complex nanoparticles were prepared by sol-gel method. The complex nanoparticles were characterized by TEM and Model 4HF VSM. The enzyme was immobilized on the particles by using nanoparticles composite as the carrier and glutaraldehyde as crosslinker.(4) The sol-gel optical complex biosensing film containing both immobilized GOD and fluorescence indicator was prepared with sol-gel method and using DDS, TEOS, hydrochloric acid, co-solvent as raw materials, Ru(bpy)3Cl2 as a fluorescent indicator. The effect of the DDS/TEOS ratios, reaction pH, drying conditions, co-solvent on the performance of the biosensing film have been investigated. The fiber optic glucose sensor based on this biosensing film has been constructed, and the characteristics of sensors such as response time, standard curve, repeatability and long-term stability were also investigated. The results showed that the fiber optic glucose sensor had the linear detection range of 50～600 mg/dL, response time of less than 20s, and better long-term stability and repeatability. The lower and upper detection limits of sensors are 10 mg/dL and 650 mg/dL, respectively.