Dual-mode fluorescence and colorimetric immunosensing platform based on Au/Pt NPs@NH2-MIL-53(Al) composite for effective detection of enrofloxacin in animal-derived foods

The fluoroquinolone-enrofloxacin (ENR) residue in animal-derived foods poses a significant threat to human health, thereby necessitating developing precise, efficient, and user-friendly detection methods. This study developed a dual-mode fluorescence-colorimetric immunosensing platform using the composite of bimetallic nanoparticles integrated with metal-organic frameworks (Au/Pt NPs@NH 2 -MIL-53(Al)). The Au/Pt NPs with biocompatibility and peroxidase-like activity were modified onto fluorescent NH 2 -MIL-53(Al) and conjugated with Ab 2 to construct signal probes. The platform enables dual-mode quantitative analysis through the competitive binding of ENR and ENR-BSA conjugate to signal probes. It demonstrated a wider linear range (0.08–180 ng/mL) and high sensitivity [LOD: 0.068 ng/mL (fluorescence), 0.066 ng/mL (colorimetric), and 0.074 ng/mL (smartphone-assisted color recognition)]. In real sample analyses, the recoveries ranged from 86.7 % to 106.7 %, with satisfactory stability (RSD ≤ 4.4 %, n  = 3). The dual-signal mode facilitates results self-calibration, enhancing reliability, while smartphone-assisted color recognition enables on-site, convenient screening, offering great potential for ENR detection in complex food matrices.