A molecularly imprinted fluorescence nanosensor based on upconversion metal-organic frameworks for alpha-cypermethrin specific recognition

A sensitive molecularly imprinted fluorescent nanosensor based on zeolitic imidazolate frameworks-8 (ZIF-8) and upconversion nanoparticles (UCNPs) was developed for the determination of trace alpha-cypermethrin (α-CPM) for the first time. The sensor was synthesized by a layer-by-layer self-assembly strategy. UCNPs with a maximum emission wavelength of 544.5 nm under 980 nm excitation were firstly prepared as the luminous core. Then, ZIF-8 with the large specific surface and porosity was introduced, which not only improved the mass transfer and adsorption capacity of the sensor but also increased the fluorescence intensity of UCNPs as a protective layer. Finally, molecularly imprinted polymers (UCNPs@ZIF-8@MIPs) were fabricated in mixed solutions containing UCNPs@ZIF-8 (support material), α-CPM (template), acrylamide (functional monomer), and divinylbenzene (cross-linker). Under the optimal condition, the fluorescence intensity of UCNPs@ZIF-8@MIP was linearly quenched with increasing concentration of α-CPM in the range 0.10-12 mg L^-1 with a detection limit of 0.03 mg L^-1 (S/N = 3). The developed UCNPs@ZIF-8@MIP probe was used to detect α-CPM in real samples; the satisfactory results obtained were consistent with those obtained by GC-MS.Graphical abstract.