Tunable Luminescent Lanthanide Cluster-Based Hydrogel Probe for Ratiometric Detection of Ofloxacin, Anti-Counterfeiting, and Magnetocaloric Applications

Misuse and overuse of antibiotics, especially Ofloxacin (OFX), have become significant global health concerns, emphasizing the urgent need for efficient and accessible detection methods. To address this issue, a series of Ln14 clusters, formulated as [Ln14(acac)24(µ4-OH)2(µ3-OH)16]·C6H14 (LnIII = GdIII (Gd14), TbIII (Tb14), EuIII (Eu14) and SmIII (Sm14)) (Hacac = acetylacetone), were successfully synthesized using the Hacac ligand and lanthanide salts in this work. Among these, Gd14 exhibits typical magnetocaloric effect behavior with the -ΔSmmax of 39.58 J kg-1 K-1 and more importantly, a ratiometric luminescent probe based on Tb9Eu5 by co-doping TbIII and EuIII ions was found enabling visual detection and reusable sensing of OFX in tap water. This marks the first application of lanthanide clusters in ratiometric luminescent detection of OFX. Further to expand the practical applications of this material, a composite film sensor was prepared by incorporating the cluster with carrageenan hydrogel, facilitating visual detection of OFX and anti-counterfeiting. The results demonstrate that the sensor possesses excellent sensitivity for OFX detection and can achieve multi-layered anti-counterfeiting through simple cutting and assembly.