Double Wall Carbon Nanotubes as Electrochemical Biosensors of NADH and Glucose

Electrochemical properties of double wall carbon nanotubes (DWCNT) were assessed. The biosensing utility of f-DWCNT film electrodes was probed by using cyclic voltammetry and amperometry of NADH and glucose. Enzyme glucose oxidase (GOx) was used as non-covalent modifier of surface of f-double wall carbon nanotubes and such assembly was used for construction of electrochemical binder-less glucose biosensor. Redox protein glucose oxidase performs as biorecognition element and double wall carbon nanotubes act both as immobilization platform for redox enzyme and as signal transducer. Significant oxidation currents, starting around +0.6 V, are observed for glucose at f-DWCNT/GOx film electrode. Data obtained showed that GOx redox enzyme successfully modified f-DWCNT. The results reveal that outer wall of oxidized double wall carbon nanotube can provide active sites for effective oxidation of biomolecules while inner wall of nanotube acts as 1D nanowire.