Detection Of Malachite Green In Aquatic Products With Ratiometric Fluorescent Probes Of Quantum Dots Coated With Molecularly Imprinted Polymer

Malachite green?MG?,a triphenylmethane compound,has once been widely employed in aquaculture due to its potent fungicidal activity.However,MG can enter the human body through aquatic products that cause diseases,which is potentially harmful to human health.Therefore,it will be of great significance to develop methods for MG rapid detection.This dissertation prepared ratiometric fluorescent probes based on the high fluorescence of QDs and molecular imprinting technology for the rapid detection of MG in aquatic products.The researches are described as follows:Part one,detection of malachite green in fish with the core-shell fluorescent probe of MIP@SiO₂@CdTe.The microspheres of SiO₂ were aminated with 3-aminopropyl-triethoxysilane to form polycations at pH 4.0,and the MPA-modified CdTe QDs formed polyanions at pH 10.0.Through electrostatic interaction,SiO₂@CdTe microspheres with strong fluorescence properties were formed by dropwisely adding the positively charged SiO₂ to QDs aqueous.And a core-shell structured MIP@SiO₂@CdTe was obtained by fabricating MIP layer on the surface of SiO₂@CdTe with precipitation polymerization method using MG,acrylamide and ethylene glycol dimethyl acrylamide as template,functional monomer and cross-linker,respectively.The fluorescence emission of MIP@SiO₂@CdTe probe at?_emm of 610 nm could be quantitatively quenched by MG with a linear range was 0.1-26?mol L^-1and a detection limit was 7.2?g kg^-1,and the quantification limit was 24.13?g kg^-1.The probe was successfully applied to the detection of MG in fish with the recoveries of 96.3-113.9%.Part two,detection of malachite green in fish with the preparation ratiometric fluorescent probe of MIPs@gQDs&rQDs.A ratiometric fluorescent probe of MIPs@gQDs&rQDs with monodispersed and spherical shape were prepared by a simple one-pot method using green-emitting fluorescent gQDs and red-emitting fluorescent rQDs as referential fluorophore and target sensitive fluorophore,respectively.The fluorescence intensity of gQDs remained unchanged in the presence of MG,while the fluorescence of rQDs could be quantitatively quenched by MG based on the strategy of fluorescence resonance energy transfer.The fluorescence ratio ofI_630/530showed good linear relationship with the MG concentrations,and the detection range of MG was 0.1 to 32?mol L^-1.The detection limit was 8.8?g kg^-1,and the quantification limit was 29.3?g kg^-1.The probe of MIPs@gQDs&rQDs has been successfully applied to the detection of MG in fish with the recoveries of 92.3-109.1%,which were validated by the method of HPLC.Part three,detection of malachite green in fish with the core-shell ratiometric fluorescent probe of MIP@PS-QDs&CDs.After modified the polystyrene microsphere?PS?with poly?diallyldimethylammonium chloride?,a fluorescent luminescence of PS-QDs was prepared by loading CdTe QDs on the surface of PS by electrostatic interaction.And the cationic agent of hexadecyl trimethyl ammonium ion was then adsorbed on the surface of PS-QDs,on which CDs@SiO₂ could self-assemble on the surface of PS-QDs to form PS-QDs&CDs with double fluorescent emission.Then,a core-shell structured ratiometric fluorescence probe of MIP@PS-QDs&CDs was prepared by fabricating MIP layer onto the surface of PS-QDs&CDs with sol-gel method using MG,?3-aminopropyl?triethoxysilan and tetraethyl orthosilicate as template,functional monomer and cross-linker,respectively.The fluorescence intensity of QDs could be linearly quenched in the presence of MG,while the fluorescence intensity of CDs remained unchanged.The probe of MIP@PS-QDs&CDs owned good fluorescence stability?RSD?2.3%?,wide linear range(0.1-32?mol L^-1)and low detection limit(5.6?g kg^-1),and the quantification limit was 18.63?g kg^-1,and has been applied to the detection of MG in fish samples with recoveries of 94.3-110.2%.