Research On Novel Metal Nano Structure Based Electrochemical Glucose Biosensor

Glucose is one of the main energy sources in human body especially in the blood system. It is of great significance for diabetes to manage their conditions by continuously monitoring the blood glucose. Therefore, to develop a rapid and high efficient method to detect glucose is extremely important. So far, a variety of methods have been reported, and among them, the electrochemical biosensor has attracted increasing interests and has become a promising technology for glucose detection due to its rapid response, good sensitivity, excellent selectivity, high reliability, low cost, portability and easy to carry and the like. There are two kinds of electrochemical biosensors:the enzyme based electrochemical biosensor and the nonenzymatic biosensor, and both of them have their own advantages and disadvantages. To some extent, the addition of inorganic nanomaterials can greatly improve the sensing properties of the biosensors. Owing to the large specific surface area, superior conductivity, excellent catalytic properties and good biocompatibility and the like, noble metal nanomaterials have some incomparable advantages, which can effectively improve the detection sensitivity and selectivity of the biosensor. Inspired by the previous research, this paper developed some novel metal nanomaterials based electrochemical enzyme and nonenzymatic glucose biosensors. The work mainly includes the following two parts:In the first part, a porous gold cluster film based electrochemical nonenzymatic glucose biosensor is developed. At first, the Au@BSA microspheres are synthesized by using bovine serum albumin (BSA) as the template. Then the Au@BSA microspheres are coated on the fluorine-doped tin oxide conducting glass (FTO). For the preparation of gold film with high surface area and low density, a’bottom up’ synthesis strategy by calcining Au@BSA microspheres is adopted in this work. The ’bottom up’method is cost-effective, environmentally friendly and simple. The resultant gold-cluster film is composed of the network structure interconnected with gold particles and the disordered 3D hierarchical pores. The constructed electrochemical nonenzymatic glucose sensor (Au-clusters/FTO) can catalyze glucose oxidation at a low potential. The detection linear range is from 10 μM to 10 mM glucose, and the detection limit is about 2 μM glucose. The nonenzymatic glucose biosensor also shows high sensitivity, excellent stability and good anti-interference ability. This work provides a useful idea of the once shaping preparation of noble metal or metal oxide film electrode for nonenzymatic direct electrochemical sensing interface by protein-templated micromaterials. Meanwhile, the preparation method is simple, low cost and easy for large-scale production, so it has various potential applications in many fields.In the second part, a novel electrochemical enzymatic glucose biosensor is constructed using the Au@Ag heterogeneous nanorods (Au@Ag heterogeneous NRs). First the Au@Ag heterogeneous NRs are synthesized by a one-pot poly (diallyldimethylammonium) chloride (PDDA)-mediated polyol process in ethylene glycol. The synthesis approach is simple, controllable and suitable for mass production. The main composition of Au@Ag heterogeneous NRs is silver (>90%), and gold nanoparticles are fully embedded in the silver and the clear boundaries of Ag and Au can be seen, leading to a typical Au@Ag heterogeneous structure. Then the electrocatalytic activity of the Au@Ag heterogeneous NRs for H2O2 reduction is investigated by building a nonenzymatic hydrogen peroxide sensor. The results show that the Au@Ag heterogeneous NRs exhibit favorable electrocatalytic ability to reduce H2O2 at negative potential and under neutral condition. The nonenzymatic hydrogen peroxide sensor also has good reproducibility and stability. Further, the glucose oxidase (GOx)/Au@Ag heterogeneous NRs modified electrode is constructed as a hydrogen peroxide reduction based electrochemical enzymatic glucose sensor. The direct electrochemistry of GOx is reached at the enzyme glucose sensor. The sensor exhibits wide glucose detection linear range of 0.02-10 mM glucose in 02-saturated phosphate buffered solution (PBS) at an applied potential of -0.4 V. Additionally, the glucose sensor shows good reproducibility and stability. Further, the proposed sensor exhibits good selectivity to common interferents (ascorbic acid, uric acid and dopamine). other saccharides, and 0.15 M chloride ions, which could be applicable for real human serum sample analysis.