Research On Glucose Biosensors Based On Au Nanomaterials

In recent years, Au nanomaterials are wildly being used in the field of biosensor and expected to enhance the performances of biosensors because of their special physical and chemical properties. In this thesis, Au nanoparticles and nanorods were used in the fabrication of optical and amperometric glucose biosensors respectively. In the preparation of the glucose sensors, we have tried different enzyme immobilization methods and investigated their influences on the performances of the biosensors.The optical glucose biosensor was based on monitoring the light absorption of Au nanoparticles produced via reaction of AuCl4- with H2O2 generated from glucose oxidation. In this sensing system, Au nanoparticles with diameter of around 5 nm were used as "seeds", where Au ions were reduced and, as a result, the seeds grew in number, resulting in the changes of the absorbance of Au nanoparticle plasmon. As the concentration of glucose increased, the absorbance was intensified. This fact could be used for detection of glucose.Three different enzyme immobilization methods were applied in the preparation of amperometric glucose biosensors and the performances of the biosensors were investigated. From the experiment results, a few conclusions could be drawn. Firstly, physical adsorption method was suitable for investigating new materials applied in biosensors because of its easy preparation and low cost. However, the dynamical range was narrow and the selectivity was not good. Secondly, electrostatic self-assembly route, used in immobilization of glucose oxidase on the Au electrode, was a better methode for fabrication of glucose biosensor with a large linear range, small apparent Michaelis-Menten constant and high sensitivity, which could be confirmed by investing performance of biosensor in the presence of artificial redox mediator, potassium ferricyanide. But the response time and selectivity were not good enough. Thirdly, chemical adsorption self-assembly, used for fabrication of Au nanoparticle enhancing glucose biosensors, could result in a biosensor with advantages of suppressing the interference from ascorbic acid, being fast response and high stability. But the process of preparation was very complicated.Au nanorods were prepared by a seeding growth approach and were used in fabricating the nanorod-enhancing glucose biosensor. Comparison of the performances among the glucose biosensors showed that Au nanoparticle enhancing biosensor via electrostatic self-assembly method had a wider linear dynamical range.