Confinement of CuNCs with aZIF-8 via one-pot encapsulation: Construction of an enzyme-free sensor toward fluorescence and smartphone detection of chlorpyrifos based on the inner filter effect

The excessive use of chlorpyrifos (CPF) has caused serious harm to food and soil safety, so, it is important for the detection of CPF. Herein, a fluorescence sensor (aZIF-8@CuNCs) consisting of copper nanoclusters (CuNCs) wrapped by amorphous zeolite imidazole framework-8 (aZIF-8) was prepared by a facile one-pot strategy to achieve selective detection of CPF. The sensing mechanism is that the fluorescence of aZIF-8@CuNCs can be quenched by 3,5,6-trichloro-2-pyridinol, the hydrolysate of CPF in alkaline condition through the inner filter effect. Therefore, a specific enzyme-free CPF sensing method was constructed by using aZIF-8@CuNCs. The detection range is 0–50 μg/mL and the detection limit reaches 0.43 μg/mL, and the recovery range of CPF in food and soil is 90.6 %-112.9 % with the relative standard deviations less than 6 %. In addition, aZIF-8@CuNCs were successfully combined with a smartphone to realize rapid visualization and quantitative analysis of CPF. This method not only reduces the difficulty of MOF@CuNCs synthesis, but also opens up a new avenue to apply it to pesticide detection in food and soil.