Construction of biosensor based on glassy carbon electrode modified by composite film of multi-walled carbon nanotubes and poly(ethylenimine)

Multi-walled carbon nanotubes (MWCNTs) were dispersed in an aqueous solution containing water-soluble poly(ethylenimine), and used to prepare MWCNTs modified glassy carbon electrode (GC/MWCNTs). A scanning electron microscopy was employed for characterizing the surface morphology of the modified electrode. The electrochemical behaviors of coenzyme (reduced nicotinamide adenine dinucleotide, NADH) on GC/MWCNTs were studied by both cyclic voltammetry and amperometry, and it is found clearly that the high overpotential for the direct oxidation of NADH on bare GC electrode was largely decreased in the presence of MWCNTs. The GC/MWCNTs electrode exhibited excellent properties as a platform for the construction of electrochemical biosensors based on NAD-dependent dehydrogenases, and an alcohol biosensor was successfully developed by immobilizing alcohol dehydrogenase on GC/MWCNTs.