A core-shell molecularly imprinted optical sensor based on the upconversion nanoparticles decorated with Zinc-based metal-organic framework for selective and rapid detection of octopamine

A sensitive fluorescent sensor for the detection of octopamine (OA) has been established by encapsulating the upconversion nanoparticles (UCNPs) into the metal-organic frameworks (ZIF-8) and incorporating molecularly imprinted polymer (MIP). The presence of ZIF-8 with high specific surface area and strong stability can improve the dispersity and emission intensity of UCNPs in the organic phase. Meanwhile, ZIF-8 membrane reduced the mass transfer resistance and adsorption time of molecularly imprinted polymers. Thus, the final UCNPs@ZIF-8@MIP sensor has exhibited the excellent optical property and the superior selective recognition ability, which was similar to natural receptors. Under the optimum condition, the fluorescence intensity of UCNPs@ZIF-8@MIP increased linearly with the concentration of OA in the range of 0.1-10 mg L-1. Compared with traditional detection methods, the current method with the detection limit of 0.081 mg L-1 would yield double functions of specific recognition and quantitative detection for OA without sophisticated preprocessing. At the spiked concentration levels of 2, 4, 6, 8 mg L-1, the recovery range of OA in beer was 81.75%-90.63% with relative standard deviation (RSD) of 2.56-5.13%.