Molecularly imprinted MOF nanozymes: Demonstration of smartphone-integrated dual-mode platform for ratiometric fluorescent/colorimetric detection of chloramphenicol.

Reliable and accurate determination of chloramphenicol (CAP) is urgently needed due to its significant implications for food safety and human health concerns. In this study, we successfully synthesized MIL-101(Fe)-NH@MIP, which exhibits peroxidase activity and a specific recognition function for CAP, through in situ polymerization of dopamine on the surface of MIL-101(Fe)-NH, utilizing molecular imprinting technology. Our bifunctional MIL-101(Fe)-NH@MIP probe offers a ratiometric fluorescent and colorimetric dual-mode sensing strategy for sensitive and selective detection of chloramphenicol. The detection limits for CAP can reach down to 36.45 nM and 93.38 nM, respectively. Furthermore, we developed a smartphone-based visual sensing platform that employs MIL-101(Fe)-NH@MIP nanozymes for rapid, portable, low-cost on-site detection of CAP. Successful spike recovery experiments conducted in fresh milk samples further validate the potential practical application of our proposed dual-mode strategy. Thus, this approach expands the applications of MOFs-based nanozymes and holds promise for antibiotic determination.