Nanozyme Colorimetric Sensor Array Based on Bimetal–OrganicFramework MIL-53 (Fe, Mn) for the Discrimination of Biological Antioxidants

Biological antioxidants play a crucial role in numerous disease-related biological processes, which has led to significant interest in their identification. In this research, a colorimetric sensor array was created. It uses MIL-53 (Fe, Mn) nanozymes to simultaneously detect multiple antioxidants. The bimetallic nanozymes, MIL-53(Fe, Mn), were synthesized by using a solvent-thermal method. This framework demonstrated notable oxidase-like catalytic ability. In particular, it facilitates the conversion of colorless TMB to a blue compound under different pH conditions. When antioxidants were introduced into the reaction system, the sensor array exhibited cross-reactivity, resulting in distinct color signals. Linear discriminant analysis (LDA) was successfully utilized to precisely identify the different concentrations of cysteine (CYS), glutathione (GSH), dopamine (DA), and ascorbic acid (AA) and their combinations. This method enabled accurate determination of the amounts of these substances both individually and in mixtures, providing a reliable way to analyze their concentrations in an experimental context. Furthermore, the prepared sensor array combined with the smartphone successfully distinguished the target antioxidants in the serum. The proposed sensing method would be expected to have practical applications in diagnosis.