L-histidine mediated synthesis of Mn3O4 nanorods with superior laccase-mimicking activity for sensitive colorimetric detection of bisphenol A

The sensitive monitoring of bisphenol A (BPA) concentration remains a critical challenge in environmental analysis and public healthcare. In this study, Mn 3 O 4 nanorods were facilely prepared in an aqueous solution at room temperature using Mn 2+ as the precursor, NaOH as the basic source and L-histidine as the mediator. The as-prepared Mn 3 O 4 nanorods exhibit excellent laccase-mimicking activity with a catalytic efficiency of 3.85 × 10 − 3 min − 1 . The catalytic mechanism was confirmed to be oxygen vacancies by electron paramagnetic resonance spectrum and enzymatic inhibition experiment. Taking advantage of the excellent laccase-mimetic properties of the Mn 3 O 4 nanozyme, a sensitive and selective colorimetric sensing platform for BPA detection was constructed. The colorimetric sensing platform achieved a linear detection range of 1–60 µM BPA and a detection limit of 0.23 µM for BPA (3σ/S). The proposed method was applicable to the determination of BPA in plastic-packaged white vinegar, bottled water and milk with good recoveries and reproducibility. This work not only provides a novel and efficient analytical tool for the rapid detection of BPA but also offers a new insight into the design and synthesis of other amino acid-mediated nanozymes for environmental monitoring applications. Graphical