The Design,Synthesis And Bioelectrochemical Application Of Novel Carbon Nanotube-graphene Nanocomposite

Being novel carbonous nanomaterial,graphene and nanotube have caused increasing interests in various fields.In the field of bioelectrochemistry,it has been found that graphene and carbon nanotube can play important roles in improving the performance of biosensors due to their large specific surface area and excellent electrical conductivity.Recently,it also has been found that graphene and nanotube have the ability to promote electron transfer reactions when utilized as electrode material.Based on this,various redox proteins or enzymes have been coupled with graphene and carbon nanotube to construct modified elec-trodes applicable in direct electrochemistry or in the production of third generation electrochemical biosensors.However,due to some inherent disadvantages,such as hydrophobicity and easy aggregation in aqueous solution,the applications of graphene and nanotube for the construction of electrochemical biosensors have been seriously limited.The recent research work demostrated that the suitable modification of graphene and carbon nanotube can not only improve the hydrophilicity of the carbonous nanomaterial,but also endowed them with better biocompability,thus greatly enhancing the performance of the as prepared electrochemical biosensors.Based on the above mentioned,the content of the thesis was summarized as follow:(1)The interaction between Bovine serum albumin(BSA)and various carbonous nanomaterial,such as graphene and carbon nanotube was investigated.Utilized BSA as a good reductant,BSA-RGO conjugates was firstly synthesized.BSA-MWNTs nanocomposite can also be prepared based on ?-? stacking interaction.Then,BSA was served as as a bridging biopolymer for the connection of carbon nanotubes and graphene,Based on that,a novel water-solube carbon nanotubes-BSA-graphene modified nanocomposites were fabricated successfully via a multi-step multi-walled self-assembly method.UV-vis spectroscopy,FT-IR spectroscopy,transmission and electron microscopy,scanning electron microscopy,Zeta potential,X-ray photoelectron spectroscopy were used to characterizitic the as prepared MWNTs-BSA-RGO nanocomposites.(2)Based on the electrostatic interaction and crosslinking method,two MWNTs-BSA-RGO based enzyme electrodes were fabricated.The direct electron transfer behaviour and the eletrocatalytic properties of the immoblized HRP on the modified electrodes were investigated respectively.It has been found that the immobilized HRP at the modified electrode well metained their native structure.Moreover,because of the biocompatibility and unique one dimensional-two dimension structure of MWNTs-BSA-RGO nanocomposites,the electron transfer between the redox center of enzymes and the electrode surface can be efficiently promoted,thus making the as-prepared HRP/MWNTs-BSA-RGO/GC electrode exhibited good catalytic electrochemical performance toward O2,H2O2 and NaNO2.Althrough the physicial adsorption immoblized method is simple,the interaction between the enzyme and the nanocomposite is weak,resulting the enzyme easily fall off from the modified electrode.By comparision,HRP can be firmly immobilized MWNTs-BSA-RGO surface via crosslinking immoblized method,thus leading to the better stability and reproducibility of the modified electrode.(3)The catalytic activity of MWNTs-BSA-RGO modified electrode toward the selective determination of DA was investigated in presence of excess amount of AA and UA.Because of the unique structure and excellent electrochemical properties of MWNTs-BSA-RGO,the modified electrode exhibit better electrocatalytic performance toward DA,such as wide linear range,high sensitivity and low detection limit.