Front-face fluorescence of tetracyclines using a modulable 3D-printed platform modified with an extraction and sensing sorbent based on rare-earth metal–organic frameworks

A stereolithographically modulable 3D-printed platform modified with a fluorescent metal-organic framework (MOF) has been developed for the selective recognition and extraction of tetracyclines, enabling their detection via front-face fluorescence spectroscopy. For this purpose, the MOF was grown in situ on the 3D-printed surface, which was previously functionalized with 2-aminoterephthalic acid, allowing the resulting composite to act as both sorptive and sensing material. Structural and morphological characterization of the MOF onto the 3D-printed device was performed using X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, and fluorescence analysis. The key advantage of the presented device is its full compatibility with conventional fluorometers, requiring no instrumental modifications since it fits directly into a standard cuvette holder. Additionally, the ability to perform measurements directly in the solid state, minimizing matrix effects thanks to the 3D-printed device functionalized with the MOF, offers a significant improvement over traditional methodologies. According to the Stern-Volmer model, the platform achieves good detection limits (1.8 and 0.5 μg L^-1 in seawater and milk, respectively), inter-device variability below 12% and recoveries exceeding 94%. Fabrication is cost-effective, with each complete unit costing only €1.60 including 3D printing, reagents, and labor (€0.5 per impact zone piece).