Study On Up-conversion Fluorescent Sensing Of Sterigmatocystin Based On Molecular Imprinting

Sterigmatocystin (ST) is a secondary metabolite produced by fungi,which often contaminates grains, feeds and the like and shows potential carcinogenic, teratogenic and mutagenic risks. At present, the methods commonly used for TS detection are chromatography, high performance liquid chromatography, liquid chromatography - mass spectrometry, etc. In this paper, a simple, sensitive and low cost fluorescence detection method is established.Based on the high selectivity of moleculary imprinted polymer and the fluorescence properties of the upconversion nanoparicles, a polymer with both selectivity and fluorescent signals is preparated to recognize trace ST with high selectivity and sensitivity. First, use yttrium acetate tetrahydrate, ytterbium acetate tetrahydrate and erbium acetate tetrahydrate to synthesize hexagonal phase upconversion fluorescent nanoparticles (UCNPs, B-NaYF4:Yb3+, Er3+) by pyrolysis, and use Triton X-100 to transfer oil phase to aqueous phase and coat a layer of SiO2 by Stober alkaline hydrolysis to synthesize a new fluorescent carrier,UCNP@SiO2, which is then used in surface-imprinte dpolymerization.The structure analogue of ST, 1,8-dihydroxyanthraquinone is used as template molecule, acrylamide as functional monomer, 3-methacryloyloxypropyltrimethoxysilane as crosslinking agent, and a new molecular imprinting technique of non-aqueous sol-gel method is used to synthesize a molecularly imprinted material with high selectivity to ST. Experiments are carried out and the synthesized fluorescent materials are characterized by transmission electron microscopy,X-ray diffraction and Fourier infrared spectroscopy. The results of adsorption experiments show that under optimal conditions, the fluorescence enhancement of fluorescent molecularly imprinted polymers increase as the concentration of ST increases. In the range of 0.05-1.0 mg L-1, fluorescence enhancement of fluorescent inprinted polymers and the concentration show a good linear relationship with a detection limit of 0.013 mg L-1.In order to verify the practicability of the established method, rice, maize and soybeans are tested for ST detection in this paper. The standard addition recovery test shows that with addition concentration of rice, maize and soybeans of 50, 100, 200 4.μg kg-1, the recovery rates are 83.8%-88.8% (RSD <5.1%), 82.1% -87.5% (RSD <4.6%) and 80.6% -89.2%(RSD <3.0%) respectively, which demonstrates the feasibility of the method established in this paper.