Polyoxometalates as peroxidase mimetics and their applications in H2O2 and glucose detection

Polyoxometalates (H3PW12O40, H4SiW12O40 and H3PMo12O40) have been proven to possess intrinsic peroxidase-like activity for the first time, which can catalyze oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to form a blue color in aqueous solution. Among them, H3PW12O40 (PW12) exhibits higher catalytic activity to TMB than natural enzyme HRP and other two POMs. In addition, H3PW12O40/graphene exhibited higher activity than H3PW12O40 in this catalytic oxidation reaction due to the effect of graphene in promoting the electron transfer between the substrate and catalyst. POMs/H2O2/TMB system provides a simple, accurate approach to colorimetric detection for H2O2 or glucose. The colorimetric method based on POMs showed good response toward H2O2 and glucose detection with a linear range from 1.34 x 10(-7) to 6.7 x 10(-5) mol/L and 1 x 10(-7) to 1 x 10(-4) mol/L, respectively. The results showed that it is a simple, cheap, more convenient, highly selective, sensitive, and easy handling colorimetric assay. (C) 2012 Elsevier B.V. All rights reserved.