Application Of Carbon Nanotubes And Graphene In Electrochemical Biosensors

Carbon nanotubes（CNT）and graphene（Gr）are novel carbon nanomaterials,which are composed of sp² hybridized carbon atoms.They have the unique properties of nanomaterials,such as large surface area,high conductivity,high chemical stability,good biocompatibility and electric catalytic activity and so on,so they can be used in the field of electrochemical biosensors.In this paper,two kinds of electrode material were suitable for the electrochemical biosensor were prepared,Au/TiO₂/CNT and Au/Gr composites,respectively,and electrochemical biosensors for synchronous detection of five biological materials were constructed.Au/TiO₂/CNT composite was prepared by an ultraviolet photocatalytic method.The Au/TiO₂/CNT modified sensing electrode was prepared by modifying the nanocomposite onto the glassy carbon electrode by pulsed electro-deposition method.Because of gold nanoparticles,titanium dioxide nanoparticles and carbon nanotubes formed a three-dimensional network structures,ascorbic acid（AA）,dopamine（DA）,uric acid（UA）,tryptophan（Trp）and nitrite（NO₂-）were successfully detected by the co-electrocatalytic synergistic effect.The Au/TiO₂/CNT/GCE had linear response ranges for detecting AA,DA,UA,Trp and nitrite of 3-281 μM,0.3-15 μM,1-162 μM,1-162 μM and 4-225 μM,respectively.The detection limits were 1 μM,0.2 μM,0.6 μM,0.8 μM and 3 μM,respectively.The composite material is characterized by good selectivity,and is suitable for coating on a variety of conductive substrate preparation of low cost,practical without enzyme sensor test paper.A selfsupporting graphene tube was prepared by hot filament chemical vapor deposition method,then gold nanoparticles were deposited on self-supporting graphene tube by multi-potential step method,a Au/Gr composite electrode was prepared.AA,DA and UA,adenine（GUA）and guanine（ADE）can be detected simultaneousl because of the high biocompatibility and electronics of gold nanoparticles,and the larger electron mobility,and a large amount of electric catalytic active sitesof grapheney.The sensing electrode testing the above five biological species,for DA and AA,DA and UA,GUA and UA,ADE and GUA,the peak potential differences reached 208 m V,140 m V,264 m V,and 360 m V,respectively.The detection limits were 0.9 μM、0.38 μM、0.75 μM、12.75 μM,and 0.5 μM,respectively.The Au/Gr electrode had good selectivity,low detection limit,high stability,and long service life.