The Application Of Carbon Nanotubes In Glucose Biosensors

Carbon nanotubes have become one of the quite popular problem in research area on each subject, owing to their significant mechanical strength, high surface area, excellent electron transmission and good chemical stability. Recently carbon nanotubes have been extensively used in electrochemical biosensor because of their subtle electron properties. Carbon nanotubes not only have the ability to promote electron transfer reaction when used as electrode modification material, but also is promising as catalyst carrier due to their high surface area.In order to develop a new potential application of MWNTs in the field of electrochemical biosensors, we have studied applications of the MWNTs in this thesis. The content consists of following three parts. In part one, covalent immobilization of MWNTs on gold electrode and the electrochemical behavior of glucose biosensor, which is using MWNTs were discussed: the electrode was first immersed in a 1mm solution of cysteamine in ethanol for 10 h to give a assembled monolayer (SAM). The electrode was then further modified with oxidatively shortened MWNTs to form a Au/MWNTs modified electrode. A new type of composite nano-material modified electrode was constructed by electrochemical deposition of platinum nanoparticles onto MWNTs modified electrode. And the morphologies were characterized by scanning electron microscopy (SEM). Experimental results indicate that high dispersed platinum nanoparticles on MWNTs (MWNTs /Pt), which has large surface area, exhibited a good electrocatalytical activity toward hydrogen peroxide. The glucose biosensor which was base on adsorption of glucose oxidase at MWNTs/ Pt substance by using gold nanoparticles results in excellent sensitivity, large linear range(0.5mM to 17.5mM), and good stability. In part two, amino group modified carbon nanotubes was discussed: With glutaraldehyde acting ascross linker, glucose oxidase has been immobilized on polylysine modified carbon nanotubes. This method of immobilization of glucose oxidase can increase the enzyme loading and therefore can increase current response. Nafion is a perfluorosulfonated polymerilfilm which have the ability to solubilize multiwall CNT. Then the glucdse biosensor1 has been developed by laying polymer Nafion and carbon nanotubes, which has been cross linked with GOx, on platinum nanoparticles1 modified gold electrode. The experimental results showed that the designed biosensor exhibited high sensitivity, rapid respond and long-term stability. In part three, the ability of polylysine to solubilize multiwall CNT and for the construction of glucose biosensor were discussed. Polylysine can adsorbe protein strongly and keep the structure of protein. In this article, the composite of CNT and glucose oxidase were laying on the platinum modified electrode to prepare glucose biosensor. Experimental results show that CNT can enhance the activity of enzyme and increase the current response. The resulting biosensor were used to detect glucose with low detection limit and fast amperometric response. Moreover, the fabrication of this biosensor is simple and it is a feasible method to detect glucose.