Synthesis of functional SiO2-coated graphene oxide nanosheets decorated with Ag nanoparticles for H2O2 and glucose detection

In this paper, we report on the first preparation of well-defined SiO2-coated graphene oxide (GO) nanosheets (SiO2/GO) without prior GO functionalization by combining sonication with sol-gel technique. The functional SiO2/GO nanocomposites (F-SiO2/GO) obtained by surface functionalization with NH2 group were subsequently employed as a support for loading Ag nanoparticles (AgNPs) to synthesize AgNP-decorated F-SiO2/GO nanosheets (AgNP/F-SiO2/GO) by two different routes: (1) direct adsorption of preformed, negatively charged AgNPs; (2) in situ chemical reduction of silver salts. The morphologies of these nanocomposites were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that the resultant AgNP/F-SiO2/GO exhibits remarkable catalytic performance for H2O2 reduction. This H2O2 sensor has a fast amperometric response time of less than 2s. The linear range is estimated to be from 1 x 10(-4) M to 0.26 M (rY = 0.998) and the detection limit is estimated to be 4 x 10(-6) Mat a signal-to-noise ratio of 3, respectively. We also fabricated a glucose biosensor by immobilizing glucose oxidase (GOD) into AgNP/F-SiO2/GO nanocomposite-modified glassy carbon electrode (GCE) for glucose detection. Our study demonstrates that the resultant glucose biosensor can be used for the glucose detection in human blood serum. (C) 2011 Elsevier B.V. All rights reserved.