Multibranched Au-Ag-Pt Nanoparticle as a Nanozyme for the Colorimetric Assay of Hydrogen Peroxide and Glucose

Many studies have recently produced artificial enzymes with metal nanoparticles (NPs) to overcome the limitations of natural enzymes, such as low stability, high cost, and storage problems. In particular, gold NPs exhibit peroxidase-like activity and are strongly influenced by external parameters, such as pH, temperature, size, shape, and functional layer, which change the enzyme activity. Here, chitosan-capped multibranched Au-Ag-Pt NPs (CCNPs) that mimic peroxidase were synthesized using various peroxidase-mimicking strategies. The results demonstrated that enzyme activity sequentially increased because of the multibranched Au-Ag NPs coated with Pt and chitosan. The enzyme activity of the particle was evaluated through the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), which causes a color change into blue. This change was observable with the naked eye and could be used practically. The color change depended on the concentration of hydrogen peroxide (H₂O₂), and it was shown that the CCNPs could be applied to measure H₂O₂ with a limit of detection (LOD) of 0.054 mM. Furthermore, with glucose oxidase, the CCNPs can be used for glucose detection with an LOD of 0.289 mM. Also, the potential of the CCNP application in human serum was shown through the serum test. Thus, this study suggested the utilization of the multibranched Au-Ag-Pt NPs that mimic the peroxidase activity of natural enzymes and the possibility of application in various biological analyses.