Embedding mediator function into laccase-like nanozymes: HAT@BPD-Cu as a self-contained laccase-mediator platform to enhance nanozyme performance.

HBT is a common laccase mediator whose N-OH group can be oxidized to generate nitroxyl radicals, thereby enhancing laccase catalytic activity. This enhancement effect has also been demonstrated in laccase-like nanozymes. However, the poor recoverability of HBT may lead to secondary pollution, which limits its environmental applications. Based on the structural homology of nitrogen-containing heterocycles, this study innovatively incorporated 1-hydroxy-7-azabenzotriazole that simultaneously features a nitrogen-containing heterocycle and an N-OH active site into the 4,4'-bipyridine-Cu-based laccase-like nanozyme (BPD-Cu), thereby constructing a leak-free composite nanozyme HAT@BPD-Cu with both a mediating active site and laccase-like activity. This approach realizes the integration of a mediating active site and laccase-like functionality within a single nanozyme-mediator composite. The resulting HAT@BPD-Cu exhibits enhanced laccase-like catalytic activity while ensuring no leakage of mediator. It shows outstanding catalytic performance and sensitive response characteristics compared to BPD-Cu in the removal of tetracycline antibiotics and the detection of 4-X-phenols (X = F, Cl, Br). This work provides novel design insights for developing recyclable, high-performance laccase-like nanozymes and introduces a new material platform for the efficient removal and analytical detection of environmental pollutants.