Fluorescent sensor based on europium metal-organic framework on a 3D-printed device for smartphone-assisted in-situ detection of tetracyclines in food samples.

This work presents a novel fluorescent sensor for the rapid and visual detection of tetracyclines (TCs) in food samples. A europium-based metal-organic framework (Eu-MOF) was immobilized onto a 3D-printed well-microplate using polyvinylidene difluoride (PVDF). Detection was performed using a 3D-printed smartphone platform, and colorimetric analysis of digital images was conducted with an ImageJ macro. For trace analysis, TCs were preconcentrated using molecularly imprinted polymer (MIP) cartridges. Under optimized conditions, the method achieved limits of detection and quantification of 0.06 and 0.2 mg L-1, respectively, with precisions below 10 % and an enrichment factor of 10. Tap water, well water, milk, and honey samples (1-12 mg L-1 TCs) were analyzed, yielding recoveries between 89 % and 112 %. The proposed method was compared with chromatographic results using regression models, including the Passing-Bablok chemometric tool, and assessed with AGREE, GAPI, and BAGI tools, highlighting its eco-friendliness and practicality compared to previously reported methods.