Bioenzyme-free dual-mode sensing for organophosphorus pesticides based on UiO-66-NH2 MOFs encapsulated tris(2,2′-bipyridyl) ruthenium(II)

Herein, we proposed a novel bioenzyme-free dual-mode sensing strategy for the rapid and accurate monitoring of organophosphorus pesticides (OPs) by preparing tris(2,2′-bipyridyl) ruthenium(II) (Ru(bpy)32+) encapsulated with UiO-66-NH2 MOFs as nanozyme (Ru@Zr-MOFs). The as-prepared Ru@Zr-MOFs nanozyme not only exhibits superior peroxidase-like activity which can catalyze O-phenylenediamine (OPD) oxidation to generate yellow 2,3-diaminophenazinc, but also exhibits dual-fluorescence feature (at 442 and 612 nm respectively) and specific interaction capacity with OPs. However, in the existence of OPs, the peroxidase-like activity of Ru@Zr-MOFs nanozyme is restricted and the oxidation process of OPD is stopped; meanwhile, the fluorescence of Ru@Zr-MOFs at 442 nm increases rapidly (< 10 s) while that at 612 nm is apathetic, thus a colorimetric and ratiometric fluorescent sensing strategy was first designed to detect OPs by using glyphosate (Gly) as a typical model of OPs. Then, in consideration of the benefits of smartphone which can make the sensing process more convenient, stable, rapid and sensitive feedback, a smartphone coupled with hydrogel detection platform was proposed also for OPs determination. In addition, the designed sensing strategy offers superior selectivity, stability and real application capabilities. It's thus expected the as-designed Ru@Zr-MOFs nanozyme based dual-mode sensing strategy possesses important real application for the low-cost, rapid, sensitive and accurate determination of OPs.