Preparation And Properties Of Xicaojing Molecularly Imprinted Photonic Crystal Hydrogel Films

Molecular Imprinting Technique(MIT)is a method for preparing polymers with specific recognition of target molecules.The internal cavities of polymers are matched with template molecules in size,space shape and action points,and the polymers have high selectivity for template molecules.The three-dimensional ordered periodic structure of photonic crystal enables it to interact with visible light and produce Bragg diffraction,showing brilliant and bright structural colors.Molecularly imprinted photonic crystal hydrogels(MIPHs)combine these two technologies to produce specific recognition and adsorption of target molecules.The adsorption of target molecules will cause some shape-shifting that will lead to changes of their lattice parameters.Bragg diffraction peaks are shifted to convert molecular signals into optical signals.In this paper,MIPHs were synthesized using polystyrene photonic crystals as template,simetryn as target molecule,then applied to the detection of simetryn in tobacco.The specific research contents are as follows:(1)Polystyrene microspheres were prepared by soap-free emulsion polymerization,which had good spherical structure and monodispersity.Polystyrene microspheres with different particle sizes were prepared by adjusting the polymerization formula,which provided the basis for the preparation of photonic crystal.(2)Based on well-dispersed polystyrene microspheres opal photonic crystals and inverse opal photonic crystals were prepared by vertical deposition and binary coassembly methods respectively.(3)MIPHs were prepared using methacrylic acid(MAA)as the functional monomer and ethylene glycol dicarboxylic acid acrylate(EGDMA)as the crosslinking agent.The responsiveness and selectivity of MIPHs to simetryn molecule were investigated,and the polymerization ratio of MIPHs was optimized.The results show that the adsorption and swelling capacity of MIPHs were the best when molar ratio of MAA to EGDMA was 5:1,and the maximum diffraction peak displacement in simetryn-acetonitrile solution reached 131 nm.(4)The molecular imprinting solid phase extraction(SPE)technique was used to purify tobacco extract and reduce the active matrix interference for the detection of simetryn in tobacco by MIPHs.At fact,the matrix interference of the spiked tobacco extract after pretreatment was reduced,and the recovery rate was between 83.19-98.62%.It was preliminarily determined that the minimum detection limit of MIPHs was 1.0 g/m L for tobacco samples extracts,which reached the macro color change condition.