Engineering Cu-Fe₃O₄/Polymer Dots Hybrids for Dual-Mode Detection of Chlortetracycline, Recognition-Enhanced Water...

Antibiotic residues in medical sewage pose public health risks, necessitating integrated detection-degradation solutions. Here, a novel Cu-Fe₃O₄/Polymer Dots hybrid (CP), featuring specific recognition of chlortetracycline (CTC), restoration of peroxidase (POD)-like activity, and outstanding fluorescence characteristics, is successfully constructed using Cu-Fe₃O₄ nanoparticles (CFO) as the core, with polymer dots (PDs) functionalizing the outer layer. Leveraging the unique properties of CP, a multifunctional platform is developed for the simultaneous fluorescence/colorimetric detection of CTC, as well as photothermal and recognition-enhanced POD activity for antibiotic degradation and bacterial disinfection. The limit of detection (LOD) for CTC by CP are determined to be 1.86 nM for fluorescence and 64.2 nM for colorimetric detection, respectively. Comprehensive characterization reveals that the fluorescence quenching of CP by CTC occurred via dynamic quenching mechanisms, primarily through intermolecular collisions. The collision between CTC and CP leads to the release of PDs, thereby exposing the active catalytic sites and reactivating POD-like activity, which not only achieves accurate detection of CTC, but also facilitates recognition-enhanced degradation of CTC and disinfection of water bacteria. This work introduces a novel approach to the design of recognition-functionalized nanozymes and offers a promising strategy for the environmental monitoring and remediation of antibiotic pollutants.