Amino Acid-Regulated Biomimic Fe-MOF Nanozyme with Enhanced Activity and Specificity for Colorimetric Sensing of Uranyl Ions in Seawater

Abstract

Nanozymes are attracting widespread attention as effective alternatives to overcome the limitations of natural enzymes. However, their catalytic performance is unsatisfactory due to the low catalytic activity and specificity. In this work, an efficient metal–organic framework (MOF) nanozyme mimicking the active centers of natural enzymes has been developed and its catalysis mechanism has been thoroughly investigated. The partial histidine- and arginine-doped Fe-MOF (HA Fe-MOF) is demonstrated to activate structure reconstruction with abundant oxygen vacancy generation, which promotes the binding capacity of HA Fe-MOF. The Fe sites in HA Fe-MOF act as catalytic sites for decomposition of H₂O₂. Intriguingly, histidine and arginine in the HA Fe-MOF can form hydrogen bonds with H₂O₂ as observed in natural enzymes, constituting a unique microenvironment that increases the local concentration of H₂O₂. Benefiting from the establishment of such enzyme-mimicking active centers, HA Fe-MOF exhibits high peroxidase-like specificity and activity. In addition, HA Fe-MOF holds great potential for detecting uranyl ions with a limit of detection as low as 0.012 μM, surpassing most reported nanozymes. This work achieves the rational design of highly specific peroxidase-like nanozymes by mimicking the structure–selectivity relationship of natural peroxidases, which provides new insights into the design of nanozymes with advanced configurations.