Hemin-functionalized WS2 nanosheets as highly active peroxidase mimetics for label-free colorimetric detection of H2O2 and glucose

Hemin-functionalized WS2 nanosheets (hemin/WS2-NSs) were first obtained by hemin assembled on the surface of few-layered WS2 nanosheets (WS2-NSs) via van der Waals interactions. Significantly, this new material possessed the advantages of both hemin and WS2 nanosheets and exhibited some unique properties. Firstly, hemin/WS2-NSs had intrinsic peroxidase-like activity, which could effectively catalyze oxidation of the substrate 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a typical blue colored reaction. Secondly, the activity of hemin/WS2-NSs was much higher than the activity of hemin or WS2-NSs alone. The catalytic activity followed the typical Michaelis-Menten kinetics and was dependent on the temperature, pH, H2O2 concentration, as well as reaction time. Based on this finding, a new highly sensitive and selective colorimetric method for H2O2 and glucose detection was developed. This method was simple and inexpensive for glucose detection using glucose oxidase (GOx) and hemin/WS2-NSs with a linear range of 0.5 x 10(-5) to 2.0 x 10(-4) mol L-1 with a detection limit of 1.5 x 10(-6) mol L-1. The good catalytic activity and low-cost make the hemin/WS2-NSs a useful biocatalyst for a wide range of potential applications in environmental chemistry, biotechnology and clinical diagnostics.