Fluorescent detection of nitrofuran antibiotics with a recordly brilliant covalent organic framework

The antibiotic residues in the water have serious effects on ecological security despite its importance for human in countering bacterium infection. The effective detection of antibiotics in drinking water could give fast, accurate diagnostic evidence, and help prevent antibiotic contamination. Herein, we report a novel fluorescent covalent organic framework (TAPA-BTD-COF) for the highly effective detection of nitrofuran antibiotics. TAPA-BTD-COF is synthesized by condensation of benzothiadiazole and tris(4-aminophenyl) amine. It exhibits an extremely strong blue fluorescence and has a record absolute fluorescence quantum yield (PLQY) in organic solvents. Besides, the COF had strong light-absorption. These properties rendered it very brilliant fluorescence, which is convenient for achieving fluorescent sensing applications. TAPA-BTD-COF exhibited efficient turn-off fluorescence response to four different kinds of nitrofuran antibiotics. Moreover, TAPA-BTD-COF fluorescence sensor exhibited a fast response to nitrofuran antibiotics with a wide detection range and linear relationship, with satisfactory LOD of 0.10 μM. And the rapid response can be achieved within 10 s. Real samples of three kinds of different water and three different kinds of meat were analyzed by adding standard recovery test. The experimental results indicated that the fluorescent sensor exhibited paralleled excellent recovery in comparison with ISO standard liquid-chromatography method. Besides, IR and XPS experiments were conducted to investigate the underlying mechanism for this efficient fluorescence sensing. The results revealed a static quenching mechanism by forming electron donor–acceptor adducts between COF sensor electron-rich triphenylamine group and nitrofuran antibiotics electron-deficient nitrofuran groups.