Bioinspired FeN Sites with Enhanced Peroxidase-like Activity Enable Colorimetric Sensing of Uranyl Ions in Seawater.

Nanozymes with peroxidase (POD)-like activity have garnered significant attention due to their exceptional performance in colorimetric assays. However, nanozymes often possess oxidase (OD) and POD-like activity simultaneously, which affects the accuracy and sensitivity of the detection results. To address this issue, inspired by the catalytic pocket of natural POD, a single-atom nanozyme with FeN configuration is designed, exhibiting enhanced POD-like activity in comparison with a single-atom nanozyme with FeN configuration. The axial N atom in FeN highly mimics the amino acid residues in natural POD to optimize the electronic structure of the metal active center Fe, realizing the efficient activation of HO. In addition, in the presence of both HO and O, FeN enhances the activation of HO, effectively avoiding the interference of dissolved oxygen in colorimetric sensing. As a proof-of-concept application, a colorimetric detection platform for uranyl ions (UO) in seawater is successfully constructed, demonstrating satisfactory sensitivity and specificity.