L‐Cysteine‐Meditated Self‐Assembled PtRu Derived Bimetallic Metal–Carbon Hybrid: An Excellent Peroxidase Mimics for Colorimetric and Fluorometric Detection of Hydrogen Peroxide and Cholesterol

Abstract Artificial enzymes have attracted considerable attention because of their significant advantages over natural enzymes. Herein, the authors report a simple hydrothermal strategy for producing a bimetallic metal — N‐, S‐doped carbon (NS‐C@PtRu) hybrid derived from L‐cysteine‐mediated self‐assembly of PtRu. The peroxidase‐like activity and colloidal stability of the NS‐C@PtRu are tuned by varying the amount of L‐cysteine, the source material for the N‐, S‐doped carbon. The NS‐C@PtRu exhibits good dispersibility, synergistic interactions (metal–metal, metal–carbon), non‐metal (N, S) doping, more catalytic active sites, improved noble metallic catalyst performance, and high utilization efficiency. As an excellent peroxidase mimic, NS‐C@PtRu catalyzes the oxidation of 3,3′,5′,5′‐tetramethylbenzidine (TMB), and Amplex Red (AR) substrates, producing colorimetric and fluorometric signals that offer efficient detection of H 2 O 2 . Furthermore, colorimetric and fluorometric cholesterol detection is proposed by combining cholesterol oxidase‐catalyzed cholesterol oxidation with NS‐C@PtRu‐catalyzed TMB/AR oxidation. The fluorometric cholesterol sensor exhibited a lower limit of detection of 1.4 µmol L −1 and rapid response, whereas the colorimetric sensor exhibited a wide detection range of 0.1–6 mmol L −1 and colorimetric changes that can be seen with the naked eyes. Both sensing methods demonstrated excellent selectivity and recovery in determining cholesterol in spiked human serum samples.