부산대학교 도서관

Colorimetric assays have drawn increasing research interest with respect to the quantitative detection of hydrogen peroxide (H2O2) based on artificial enzymes because of their advantages with respect to natural enzymes, including design flexibility, low cost, and high stability. Regardless, the majority of the artificial enzymes exhibit low affinity to H2O2with large Michaelis–Menten constants (Km). This indicates that the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue-colored oxTMB requires a high H2O2concentration, hindering the sensitivity of the colorimetric assay. To address this problem, novel reduced Co3O4nanoparticles (R-Co3O4) have been synthesized in this study via a step-by-step procedure using ZIF-67 as the precursor. R-Co3O4exhibits a considerably enhanced peroxidase-like activity when compared with that exhibited by pristine Co3O4(P-Co3O4). The catalytic process in the case of R-Co3O4occurs in accordance with the typical Michaelis–Menten equation, and the affinity of R-Co3O4to H2O2is apparently higher than that of P-Co3O4. Furthermore, the density functional theory calculations revealed that the introduction of oxygen vacancies to R-Co3O4enhances its H2O2adsorption ability and facilitates the decomposition of H2O2to produce ·OH radicals, resulting in improved peroxidase-like activity. A simple and convenient colorimetric assay has been established based on the excellent peroxidase-like activity of R-Co3O4for detecting H2O2in concentrations of 1–30 μM with a detection limit of 4.3 × 10–7mol/L (S/N = 3). Furthermore, the R-Co3O4-based colorimetric method was successfully applied to glucose detection in human serum samples, demonstrating its potential for application in complex biological systems.