▎ 摘　　要

Most graphene-metal nanocomposites for biosensing are formed using noble metals. Recently, development of nanocomposites using rare earth metals has gained much attention. This paper reports on the development of a nanoceria-nanoplatinum-graphene hybrid nanocomposite as a base transducing layer for mediator-free enzymatic biosensors. The hybrid nanocomposite was shown to improve detection of superoxide or hydrogen peroxide when compared to other carbon-metal hybrid nanocomposites. Based on this finding, the nanocomposite was applied for biosensing by adding either a peroxide-producing oxidase (glucose oxidase), or a superoxide-producing oxidase (xanthine oxidase). Material analysis indicated that nanoceria and nanoplatinum were equally distributed along the surface of the hybrid material, ensuring detection of either superoxide or hydrogen peroxide produced by oxidase activity. Glucose biosensors demonstrated a sensitivity (66.2 +/- 2.6 mu A mM(-1) cm(-2)), response time (6.3 +/- 3.4 s), and limit of detection (1.3 +/- 0.6 mu M) that were comparable to other graphene-mediated electrodes in the current literature. Remarkably, XOD biosensor sensitivity (1164 +/- 332 mu A mM(-1)), response time (5.0 +/- 1.5 s), and limit of detection (0.2 +/- 0.1 mu M) were higher than any reported biosensors using similar metal-decorated carbon nanomaterials. This material is the first demonstration of a highly efficient, diverse nanoceria/nanoplatinum/graphene hybrid nanocomposite for biosensing. (C) 2014 Elsevier B.V. All rights reserved.