Single-nanozyme based sensor array: mesoporous hollow melanin-CuS with dual-enhanced peroxidase-like and specific recognition activities for sensitive discriminative detection of fluoroquinolones

Antibiotic residues threaten ecosystems and human health, but current nanozyme-based colorimetric sensors suffer from weak activity and low interference resistance. Here, we address these challenges with a rationally designed mesoporous hollow polydopamine-copper sulfide (MHPDA-CuS) hybrid nanozyme. The nanozyme exhibits dramatically enhanced catalytic efficiency, with K m values for TMB and H 2 O 2 (0.146 and 0.206   mM, respectively) being 5.29- and 17-fold lower than those of horseradish peroxidase. Attractively, fluoroquinolones (FQs) function as dual-functional cofactors that dramatically boost the activity of the hybrid nanozyme due to the specific interaction of FQ with both PDA and copper ions in the nanozyme. The effect is closely linked to their molecular structure. This finding enables a three-channel colorimetric sensor array that rapidly (<10   min) discriminates multiple FQs with ultrahigh sensitivity (limit of detection, LOD < 1   nM) at a nanozyme dosage 100-fold lower than conventional methods. This dual-regulation strategy provides a powerful, facile tool for environmental and food safety monitoring and advances the structure-function understanding of polymer-metal hybrid nanozymes.