Platinum Nanoparticles Loaded Graphitic Carbon Nitride Nanosheets with Enhanced Peroxidase-like Activity for H(2)O(2) and Oxidase-Based Sensing

Platinum nanoparticles (PtNPs) are classical peroxidase-like nanozyme; self-agglomeration of nanoparticles leads to the undesirable reduction in stability and catalytic activity. Herein, a hybrid peroxidase-like nanocatalyst consisting of PtNPs in situ growing on g–C(3)N(4) nanosheets with enhanced peroxidase-mimic catalytic activity (PtNP@g–C(3)N(4) nanosheets) was prepared for H(2)O(2) and oxidase-based colorimetric assay. g–C(3)N(4) nanosheets can be used as carriers to solve the problem of poor stability of PtNPs. We observed that the catalytic ability could be maintained for more than 90 days. PtNP@g–C(3)N(4) nanosheets could quickly catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), and the absorbance of blue color oxidized TMB (oxTMB) showed a robust linear relationship with the concentration of H(2)O(2) (the detection limit (LOD): 3.33 μM). By utilizing H(2)O(2) as a mediator, this strategy can be applied to oxidase-based biomolecules (glucose, organophosphorus, and so on, that generate or consume hydrogen peroxide) sensing. As a proof of concept, a sensitive assay of cholesterol that combined PtNP@g–C(3)N(4) nanosheets with cholesterol oxidase (ChOx) cascade catalytic reaction was constructed with an LOD of 9.35 μM in a widespread range from 10 to 800 μM (R(2) = 0.9981). In addition, we also verified its ability to detect cholesterol in fetal bovine serum. These results showed application prospect of PtNP@g–C(3)N(4) nanosheets-based colorimetry in sensing and clinical medical detection.