A high-performance fluorescence immunoassay based on pyrophosphate-induced MOFs NH2-MIL-88B(Fe) hydrolysis for chloramphenicol detection

In this work, we firstly found and verified that pyrophosphate (PPi) can form a competitive coordination effect with the metal-organic frameworks (MOFs) NH2-MIL-88B(Fe), causing the MOFs structure to collapse and release diaminoterephthalic acid (NH2-BDC), and then weakening the ligand-metal charge transfer (LMCT) of the MOFs network structure, allowing the original fluorescence of NH2-BDC be recovered. Based on this new principle, synthesized high-stability MOFs NH2-MIL-88B(Fe) were employed as fluorescent signal sources to trace target recognition, and MOFs fluorescent immunoprobes were prepared by chemically coupling anti-chloramphenicol (CAP) monoclonal antibodies via the active ester method (EDC/Sulfo-NHS). A direct competitive fluorescence immunoassay was established for the detection of CAP residues in milk samples, in which the limit of detection (LOD) was 0.028 μg L−1, the linear range was 0.05–0.75 μg L−1, and the recovery rate was 91.8%–112.3%. This study employed a simple and time-saving one-step method for releasing fluorescent signals, which was also useful for the rapid and accurate detection of CAP residues.