Controllable Synthesis of an Upconversion Metal–Organic Framework Core–Shell Hybrid for Highly Sensitive Fluorescence Detection of Dufulin in Crops and Fruits

Developing a sensitive analysis of dufulin with high anti-interference performance remains challenging. Herein, a metal-organic framework (MOF)-encapsulated upconversion nanoparticle (UC) core-shell hybrid sensor (UC@CuMOF) was designed for the sensitive detection of dufulin. With the encapsulation of the CuMOF shell, the luminescence of UC under a 980 nm laser was strongly quenched by the shell through the photoinduced electron transfer effect. Based on acetylcholinesterase (AChE)-catalyzed hydrolysis of acetylthiocholine into thiocholine and dufulin's inhibition of AChE activity, the UC@CuMOF displayed a sensitive response to thiocholine by AChE and thus was pioneered as a high-efficiency sensor for dufulin with a detection limit of 8.86 pg mL^-1. Due to the special excitation wavelength, the interference caused by pigments in plants excited by visible light was effectively avoided. Therefore, this research demonstrated the viability and promise of upconversion nanosensors in agricultural and environmental samples and provided a promising application foreground for the sensitive analysis of dufulin.