Improved peroxidase mimetic activity of a mixture of WS2 nanosheets and silver nanoclusters for chemiluminescent quantification of H2O2 and glucose.

It is reported that a mixture of WS2 nanosheets (WS2 NS) and silver nanoclusters (AgNCs) displays strongly enhanced peroxidase-mimicking activity. The catalytic effect of the mixture was studied by colorimetry, fluorometry, chemiluminescence (CL) and electrochemistry. The effect is interpreted in terms of a difference between the Fermi energy level of the two nanomaterials. This leads to the formation of charge separation regions which act as active sites for enzyme mimetic interaction with the substrates. The mixture of WS2 NS and AgNCs was exploited for the non-enzymatic determination of H2O2 and glucose. A stopped-flow method was applied as a sensitive CL detection system using the bicarbonate-H2O2 reaction. The mixture has a powerful peroxidase mimicking activity on the bicarbonate-H2O2 CL reaction, and this effect is much larger than that of any single constituent. In addition, the CL emission is improved several times by using the stopped-flow technique. Under optimum condition, H2O2 can be determined in the 2.5-1500 nM concentration range. Moreover, glucose levels in human serum can be quantified via glucose oxidase based oxidation which leads to the generation of H2O2. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.03-20 μM, with a limit of detection (3S) of 13 nM. Graphical abstract An enhanced peroxidase-like catalytic activity for WS2 nanosheets (WS2 NS) was revealed in the presence of silver nanoclusters (AgNCs), and was exploited for the non-enzymatic determination of H2O2, and of glucose (via glucose oxidase; GOx) using a stopped-flow CL method.