Fabrication of free-standing graphene composite films as electrochemical biosensors

Abstract

We report a simple fabrication method for large-scale free-standing graphene-gold nanoparticle and graphene-single wall carbon nanotube composite films by using a centrifugal vacuum evaporation followed by a thermal reduction process. The homogeneous mixture of a graphene oxide (GO) suspension with gold nanoparticle (Au NP) or single wall carbon nanotube (SWCNT) is self-assembled at the air/liquid interface, resulting in the multilayered GO-Au NP and GO-SWCNT composite films. The cross-sectional image reveals that the graphene layers are orderly stacked in the reduced GO-Au NP film, while the reduced GO-SWCNT film shows a randomly packed morphology due to the dominant pi-pi interaction between the side wall of SWCNTs and the GO surfaces. In particular, the reduced GO-Au NP film shows an increased electrode kinetics and cyclic voltammetric response in proportion to the amount of Au NPs, and 3-fold enhancement of anodic peak current was observed compared with that of the reduced GO films. We employed the reduced GO-Au NP film as a matrix to immobilize tyrosinase enzyme for phenol detection, and the phenol-induced electrochemical catalytic reaction can be monitored with 3-fold higher sensitivity than the reduced GO film, demonstrating great potential of graphene composite as an electrochemical enzyme biosensor for environmental pollutant screening. (C) 2011 Elsevier Ltd. All rights reserved.