PtS2 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 2 nanosheets with good reproducibility. Herein, intrinsic peroxidase-like activity was for the first time demonstrated for PtS 2 nanosheets, which can catalyze H 2 O 2 oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to generate a colored solution. The catalytic mechanism of PtS 2 nanosheets was investigated, which indicated that acceleration of the electron transfer between TMB and H 2 O 2 was the main reason for the peroxidase-like activity of PtS 2 nanosheets. Based on these observations, we exploited PtS 2 nanosheets integrated into dopamine-functionalized hyaluronic acid (HA-DA) hydrogel microspheres by droplet microfluidics to construct PtS 2 nanosheet– and PtS 2 @HA-DA microsphere–based sensors for highly sensitive determination of H 2 O 2 . When coupled with glucose oxidase, we further developed two glucose sensors based on the above two methods. Among them, the linearity of the PtS 2 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. Graphical abstract