Ultra-sensitive detection of florfenicol by flow injection chemiluminescence immunoassay based on Nickel/Cobalt bimetallic metal–organic framework nanozymes

Abstract

The emergence and progress of metal–organic frameworks (MOFs) with high stability, large surface area, and abundant unsaturated active sites, once again promote the development of nanozymes, making nanozymes more advantageous to replace natural enzymes and will increase the applications of chemiluminescence immunoassay. In this study, a flow injection chemiluminescence immunoassay based on Ni/Co metal–organic framework (Ni/Co-MOF) nanozymes was developed, which can quickly and highly sensitively detect florfenicol (FF) in animal-derived food residues. Ni/Co-MOF_0.75 nanospheres can not only form stable immune probes with antibodies but also act as nanozymes to efficiently catalyze H₂O₂ for amplifying the chemiluminescence signal of the luminol–H₂O₂ system. In addition, due to good biocompatibility and large specific surface area, carboxyl-modified resin beads are used as a suitable material for loading more coating antigens. Based on the principle of competitive immunity, FF standard solution will compete with coating antigen loaded on the carboxyl resin beads for the limited binding sites on the FF antibody. Under the best experimental conditions, the detection range of FF is 0.0001–1000 ng mL⁻¹, and the detection limit (LOD) is 0.033 pg mL⁻¹ (S/N = 3). Furthermore, this method has been successfully applied to the analysis of actual samples with satisfactory results, which will provide a certain reference for the detection of small molecules in food and environmental analysis.