Hydrogel-Involved Portable Ratiometric Fluorescence Sensor Based on Eu3+/Cds-Modified Metal-Organic Framework for Detection of Ofloxacin and Tetracycline

Abstract

Highly selective and sensitive monitoring low-concentration ofloxacin and tetracycline residues is meaningful for food safety and environmental protection. Herein, benefitting from strong coordination capability and good porosity of metal-organic framework UiO-67b, the dual-functional fluoroprobes were developed based on UiO-67b post-modified by luminescent Eu3+ and carbon dots (CDs). Eu3+ coordinated with bipyridine groups in the ligands and CDs distributed in the pores/surface endowed UiO-67b dual recognition sites with controllable and distinguishable red and blue emissions, which could be quenched by ofloxacin and tetracycline through internal filtering effect resulting in distinct color change from red to blue. Based on this, the ratiometric fluorescent assay was first established towards ofloxacin and tetracycline in the ranges of 0-60/0-10 µM, reaching a low limit of detection of 22/27 nM. Satisfactory recoveries of 98.5-103.7% in real samples as well as visual analysis endow such intelligent sensing platform great potential on practical evaluating antibiotic residues in food.

Keywords: antibiotics, Metal-organic framework, Ratiometric fluorescence, Visual analysis, Smartphone