The fabrication of a colloidal gold-carbon nanotubes composite film on a gold electrode and its application for the determination of cytochrome c.

Colloid Au (Au(nano)) with a diameter of about 20 nm was prepared and used in combination with the multi-wall carbon nanotubes (MWNTs) to modify a gold electrode. Dihexadecylphosphate (DHP) dispersed in Au(nano) aqueous solution was used to solubilize MWNTs. Deposition of Au(nano) on MWNTs was realized as illustrated by TEM micrographs. The DHP formed a network that connected Au(nano) and MWNTs to the gold electrode surface. The Au(nano)-MWNTs-DHP composite film on the gold electrode surface was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammmetry (CV). The composite film modified gold electrode was used to detect cytochrome c and a pair of well-defined redox waves was obtained. It was found that the composite film promoted the redox of horse heart cytochrome c and its effect was developed for the determination of cytochrome c.