Biomimetic ratiometric fluorescent sensor with MOF-confinement signal amplification and PQDs quenching for sensitive ciprofloxacin detection.

Sensitive and specific detection of ciprofloxacin (CIP) is essential for ensuring food safety. Herein, a novel ratiometric fluorescent sensor integrating zirconium-based metal-organic framework (UiO-66), perovskite quantum dots (PQDs), and molecularly imprinted polymers (MIPs) was developed. The fluorescent sensor leveraged the porosity of UiO-66, the selectivity of MIPs, and the excellent optical properties of PQDs. Upon CIP binding, the green fluorescence (FL) of PQDs at 507 nm was quenched via electron transfer, while the intrinsic blue FL of CIP at 433 nm emerged. Notably, the confinement effect within UiO-66 significantly amplified the CIP signal. The ratiometric enhancement factor FL (REF) was linearly related to the CIP concentrations ranging from 0.03 to 20 mg/L, with a limit of detection of 0.014 mg/L. The sensor was successfully applied for quantifying CIP in aquatic samples, achieving recovery rates of 97.1 %-101.3 %. This work provides a universal blueprint for design of MOF-confined self-calibrating ratiometric sensor for CIP detection.