PtS nanosheets as a peroxidase-mimicking nanozyme for colorimetric determination of hydrogen peroxide and glucose.

Using an ultrasonication-assisted liquid exfoliation method, we have synthesized PtS nanosheets with good reproducibility. Herein, intrinsic peroxidase-like activity was for the first time demonstrated for PtS nanosheets, which can catalyze HO oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to generate a colored solution. The catalytic mechanism of PtS nanosheets was investigated, which indicated that acceleration of the electron transfer between TMB and HO was the main reason for the peroxidase-like activity of PtS nanosheets. Based on these observations, we exploited PtS nanosheets integrated into dopamine-functionalized hyaluronic acid (HA-DA) hydrogel microspheres by droplet microfluidics to construct PtS nanosheet- and PtS@HA-DA microsphere-based sensors for highly sensitive determination of HO. When coupled with glucose oxidase, we further developed two glucose sensors based on the above two methods. Among them, the linearity of the PtS nanosheet-based spectrophotometry was in the range of 0.5 to 150 μM and the limit of detection as low as 0.20 μM. The linearity of the microsphere-based colorimetry was in the range 200 to 12,000 μM with a detection limit of 29.95 μM. Both of the glucose sensors can be applied to the determination of glucose in human serum with reliable results and reproducibility.