A new hydroxyl group functionalized Zn-MOF as an efficient fluorescent probe for sulfasalazine residue detection in water, milk and soil

Sulfasalazine (SSZ) is a typical sulfonamide antibiotic. The extensive use of SSZ in animal husbandry and agriculture has lead to antibiotic residue in the environment, which ultimately harm human health. The pursuit of simple and efficient methods for the detection of SSZ is highly desirable, yet it remains a challenging task. Herein, a new hydroxyl group functionalized Zn-MOF probe (MOF-1) was revealed for the highly selective and sensitive sensing of SSZ. MOF-1 was constructed with Zn(NO3)2·6H2O, 3,3′-dihydroxy-4,4′-biphenyl dicarboxylic acid (DDA) and 1, 2, 4, 5-tetra(4-pyridyl)benzene (TPB) by using the solvothermal method. Strong fluorescent emission centered at 460 nm was observed for MOF-1 which could be quenched by SSZ. Selectivity experiments indicate that MOF-1 is highly selective response to SSZ among 18 antibiotics. Fluorescence titration experiments suggest that MOF-1 is highly sensitive to SSZ with a detection limitation of 31 nM. Based on the impressive characteristics of MOF-1 such as fast response and good reusability, portable test strips were prepared and used as naked eye kits for real-time SSZ detection. Moreover, the sensing mechanism was proposed based on the experimental and theoretical calculation results.