Micro Wave Plasma Treated Carbon Nanotubes And Their Application In Glucose Biosensor Construction

Carbon nanotube (CNTs), as a kind of nano material, can produce special catalytic action to some materials because of its small particle diameter and large surface area. So they are often been used to construct enzymatic biosensors. Electrochemical enzymatic biosensors based on the recognition of specific substrates have the advantages of high sensitivity and nice selectivity as well as easy miniaturization and automation. In the design and fabrication of the electrochemical biosensors the crucial step is how to develop a simple and effective strategy for the construction of sensitive membrane on the electrodes. This research is aimed to develop new immobilization strategies of enzyme for the purpose of improving the performance and long-term stability of biosensor. The details are summarized as follows:1. A micro wave plasma treatment method was proposed to enhance the solubility of carbon nanotubes (CNTs). The CNTs were treated by micro wave plasma with ammonia as a precursor, and the resultant ammonia plasma-treated CNTs (ammonia PT-CNTs) were conveniently obtained. The FTIR and XRD spectra well demonstrated that the carbon skeleton structure was not destroyed as well as amine groups of different forms were successfully coupled to CNTs in the MWP treatment process. Meanwhile, the excellent solubility of the ammonia PT-CNTs in aqueous solution was also observed by photographs. By choosing glucose oxidase as a model enzyme, the application of the ammonia PT-CNTs in construction of biosensors was further investigated. Due to the biocompatibility and electron transfer capability of ammonia PT-CNTs, the glucose oxidase (GOD) biosensor displayed a good sensing performance. The biosensor had a fast response of less than 10 s, and the response current linearly increases with the glucose concentration in the range of 1.2×10-4 to 7.5×10-3 M with a detection limit of 1.0×10-5 M.2. To improve the electron transfer capability of carbon nanotubes, a ferrocene- carbon nanotubes were prepared, where carboxyl ferrocene were covalently coupled to ammonia PT-CNTs through carbondiimide reagent. Cyclic voltammetric curves well demonstrated the better electrochemical behavior of the ferrocene-carbon nanotubes as well as the presence of ferrocene groups. A glucose biosensor was constructed by mixing the carboxyl ferrocene, glucose oxidase, chitosan to form a...