UV/Visible Photoresponsive Surface Molecularly Imprinted Polymers For The Application In The Detection Of Organophosphorus Pesticides In Vegetables And Fruits

Photoresponsive surface molecularly imprinted polymers are made by combining photoresponsive polymers with surface molecular imprinting technology.The response mechanism is that the shape and size of the imprinted cavity inside the photoresponsive surface molecularly imprinted polymer changes under the trigger of a clean light source,and the template molecules adsorbed in the imprinted cavity are squeezed into the environment.When the imprinted cavity recovers to its original size and shape under the illumination of another light source,the polymer will selectively adsorb template molecules in the environment.The above trigger mechanism has the advantages of greenness and high selectivity.At the same time,molecularly imprinted polymers can reduce the interference of complex food sample matrices on detection,which has attracted widespread attention in the field of food safety.Therefore,a light-responsive surface molecularly imprinted polymer that responds to ultraviolet light and visible light is constructed in this paper for the detection of trace organophosphorus pesticides in vegetables and fruits.This dissertation contains five chapters,specific contents are described as follows:1.The first chapter review the development of molecularly imprinted polymers firstly.And then outlines the choice of template molecules,functional monomers,cross-linkers,and substrates for photoresponsive surface molecularly imprinted polymers and the applications of photoresponsive surface molecularly imprinted polymers.Finally,the properties,deleterious effect,global use,and common detection of organophosphorus pesticides are overviewed.2.In the second chapter,a method based on UV/visible light-responsive surface molecularly imprinted polymer for the detection of organophosphorus pesticides profenofos in vegetables and fruits was constructed.This method utilized the hydrogen-bonding interactions between the carboxyl groups on the polystyrene surface and the carboxy-azobenzene derivative 4-??4-?methacryloyloxy?phenyl?diazenyl?benzoic acid?MPABA?to drive MPABA and cross-linker trimethylacryloyloxyethylamine?TEAMA?polymerize on the carboxyl-capping polystyrene?PS-co-PMAA?.After that,the effect of DMSO and H₂O mixed solutions of different volume ratios of on the photoisomerization rate of MPABA were investigated.And the effect of solvents,the ratio of PS-co-PMAA/monomer?m/m?and the ratio of cross-linker/monomer?n/n?on the yield and morphology of PS-co-PMAA@PSMIP materials were discussed.Meanwhile,the effect of the ratio of cross-linker/monomer?n/n?on the photoisomerization rate of PS-co-PMAA@PSMIP materials were investigated.What's more,the relationship between the photoisomerization rate constant of PS-co-PMAA@PSMIP material and the concentration of profenofos was studied,and the content of profenfos in spiked tomato and mangosteen samples were detected,in which the relative standard deviation and recovery was calculated.3.In chapter three,a method based on visible light responsive surface molecularly imprinted polymer for detecting organophosphorus pesticide chlorpyrifos in vegetables and fruits was constructed.In the synthesis of visible light responsive surface molecularly imprinted polymer PS-co-PMAA@VSMIP,which is responsive under the irradiation of monochromatic light with 550 nm and 440 nm,visible light-responsive carboxy-azobenzene derivative3,5-dichloro-4-??2,6-dichloro-4-?methacryloyloxy?phenyl?diazenyl?benzoic acid?DDMPDBA?,trimethylolpropane triacrylate?TMPTA?,chlorpyrifos?CPF?and carboxyl-capping polystyrene?PS-co-PMAA?were respectively used as a functional monomer,cross-linker,template molecule and substrate.Firstly,the photoresponse performance of DDMPDBA was studied under different solvents and monochromatic light at different wavelengths.Secondly,the effect of solvents,the ratio of PS-co-PMAA/monomer?m/m?and the ratio of cross-linker/monomer?n/n?on the yield and morphology of PS-co-PMAA@VSMIP materials were discussed.Meanwhile,the effect of the ratio of cross-linker/monomer?n/n?on the photoisomerization rate of PS-co-PMAA@VSMIP materials were investigated.And the release and uptake of chlorpyrifos was realized by switching the irradiation of monochromatic light at 550 nm and 440 nm on polymer materials.What's more,the relationship between the photoisomerization rate constant of PS-co-PMAA@VSMIP material and the concentration of chlorpyrifos was studied,and the content of chlorpyrifos in spiked carrots and apples samples were detected,in which the relative standard deviation and recovery was calculated.4.In Chapter 4,a hollow visible light responsive surface molecularly imprinted polymer?HVSMIP?was constructed for the detection of chlorpyrifos in vegetables and fruits.Based on the PS-co-PMAA@VSMIP material prepared in Chapter 3,the HVSMIP materials was obtained by removing the core PS-co-PMAA.Under the same test conditions as the PS-co-PMAA@VSMIP material in Chapter 3,the binding kinetics,equilibrium rebinding,Binding selectivity,and photoregulated release and uptake experiments of HVSMIP were studied,meanwhile the binding of the PS-co-PMAA@VSMIP materials was considered as control group.And compared the photo-isomerization rate of PS-co-PMAA@VSMIP material with HVSMIP material.What's more,the relationship between the photoisomerization rate constant of HVSMIP material and the concentration of chlorpyrifos was studied,and the content of chlorpyrifos in spiked carrots and apples samples were detected,in which the relative standard deviation and recovery was calculated.Finally,this method was used to determine the content of chlorpyrifos in carrots in three local supermarkets.5.In the last chapter,all the research work and experimental results of this paper were summarized.The advantages and disadvantages of polymer materials prepared from two carboxyazobenzene derivatives of MPABA and DDMPDBA in the field of food safety testing were compared.What's more,the advantages and disadvantages of detection methods of CPF constructed by PS-co-PMAA@VSMIP and HVSMIP were compared.On this basis,the future research work were prospected.