Synthesis Of Nanomaterials And Their Application In Glucose Biosensor

Glucose detection is very important in many fields including food processing and fermentation, clinical, biological, and chemical. Developing a fast and reliable method for glucose determination is an urgent demand for these applications. Many techniques, such as fluorescence, Fehling reagent method, optical rotation method, surface plasmon resonance, and electrochemistry have been developed for this purpose. Among of these techniques, electrochemical method attracted more attention due to its good selectivity, high sensitivity, simplicity, reproducibility, low cost, and easy to carry on the on- line continuous monitoring in complex system. Using GOD as the electrochemical active center to design glucose sensor is the best choice. However, it is very difficult to achieve direct electrochemistry of most redox proteins due to the deeply buried redox centers in the proteins. Up to now, only very few redox proteins could realize direct electron transfer on the surface of bare or naked solid electrodes, and it is easily affected by surroundings. Further, the development of nanomaterials promote the advancement of electrochemical sensor. Nanomaterial play important role in fixing enzyme and conducting electron in enzymatic sensor. However, the instability of enzyme is still a big problem. In order to overcome the shortcoming of enzyme based biosensor, non-enzymatic sensor was put forwarded, which owns good stability and friendly environmental adaptability. But low anti- interference ability is limited its application in complex system. Designing specific catalyst is a way for improving sensor’s selectivity. So it is of significance for developing efficient glucose sensor to synthesize functional nanomaterials.This paper makes a comprehensive review and summary of the detection principles, development status, advantages and disadvantages of glucose oxidase-based biosensors and non-enzymatic glucose biosensors. In order to improve the overall performance of biosensor, we research the effect of nanomaterial’s type and immobilizing method on the performance of enzymatic sensor. Moreover, we discuss the feasibility of non-enzymatic detection of glucose based on cobalt phosphide modified electrode. The main contents of this paper is as follows:1. We synthesizes tungsten oxide with different morphologies including aerogel, nanorods and nanoparticles. Further, immobilize GOD on different nanostructures. The electrochemical results indicates that tungsten oxide aerogel exhibits best biosensing performance, which is contributed from the network structure consisted of crisscross nanowires. GO D realizes direct electron transfer and detecting glucose with the help of tungsten oxide aerogel. Its sensitivity is 2.69×10-4 m A/mmol cm2, response time is about 10 s, and the linear range is from 0.01 m M to 1.0 m M.2. Immobilizing enzyme by using nanomaterial usually prepare material first, then mix it with enzyme. This method take advantage of the adsorption properties of nanomaterials owing to its small size, which calls adsorption method. B ut glucose oxidase can dissolve in water easily, so the prepared electrode is not stable in the detection process. In order to solve the problem, we use an in situ-growth method to reduce silver onto enzyme so as to combine them firmly. In detail, a silver mirror reaction is conducted in the solution of glucose oxidase to obtain Ag-GOD composite, which is used for constructing working electrode. In comparison, traditional adsorption method is also conducted at the same condition. As a result, the former has a fast response time of less than 5 s, a linear range of 0.014-3 m M, while the later one’s response time is longer than 20 s, and linear range is within 1 m M. That is to say, in situ method is more advantageous than adsorption method.3. In order to overcome the shortcoming of enzyme based sensor, we also research the non-enzyme based glucose sensor. Cobalt phosphide owns good catalysis property, which is usually used for electrocatalytic hydrogen production. In this article, we synthesize cobalt phosphide na norod and use it for glucose detection. Electrochemical measurement indicates cobalt phosphide has a good detection performance for glucose even at a low applied potential. According to the analysis for the morphology, crystal structure and surface chemical station, combined with electrochemical data and theoretical calculation, we discuss the feasibility of detecting glucose by cobalt phosphide nanorod.