Abstract
A composite was prepared from copper and graphene oxide (Cu-GO) by in-situ chemical reduction of a mixture containing GO and Cu(II) ions with potassium borohydride. The morphology and structure of the composite were confirmed by various physicochemical techniques. The materials were used in a tyrosinase-based microbiosensor where the enzyme is immobilized in a biocompatible matrix consisting of poly(ortho-phenylene diamine) and Cu-GO. The composite was deposited on the surface of an 8-mu m thick carbon fiber microelectrode. The role of each component in the sensing layer was systematically investigated with respect to the analytical performance of the system. In its optimal configuration, the biosensor demonstrated (a) a sensitivity of 6.1 +/- 3 nA mM(-1) dopamine (DA), (b) a linear response to DA (with a Michaelis-Menten constant of 0.29 +/- 0.03 mM), (c) good selectivity over ascorbic acid and uric acid, and (d) a high blocking capacity (112.2 +/- 2 mM) for ascorbic acid.