A Smartphone Sensing Platform Based on Multilanthanide Metal–Organic Framework Sensors for Portable Visual Quantitative Detection of Antibiotic Residues

Both enrofloxacin and tetracycline hydrochloride are widely used antibiotics, and the harm caused by their abuse affects the ecological balance and human health. In this study, La-MOFs based on polycarboxylate ligands were prepared and three functionalized multilanthanide metal–organic framework sensors were obtained by in situ doping of Eu3+ and Tb3+. Fluorescence experiments showed that the fluorescence intensity of MOFs had a good linear relationship with the detected antibiotics and a low detection limit, and the MOFs had good anti-interference performance. Subsequently, the detection effect of enrofloxacin and tetracycline hydrochloride in actual samples (tap water, milk, shrimp, and pork) was tested by a standard addition recovery experiment; the recovery rate was between 90.5 and 107.4%, and the RSD was less than 5%. The MOFs@PVDF film, combined with smartphone imaging technology and RGB recognition technology, can be successfully used for rapid and convenient visual quantitative detection of enrofloxacin and tetracycline hydrochloride. Finally, the fluorescence quenching mechanism of MOFs by FRET and IEF was revealed. The multilanthanide MOF sensors developed can achieve highly sensitive visual detection of antibiotics and provide a portable solution for environmental and food safety monitoring, and their low-cost characteristics are expected to promote the practical application of intelligent detection equipment.