Preparation And Performance Research Of Gold Nanoparticle-Quantum Dots Fluorescent Probe

Quantum dots（QDs）are widely used in various fields（e.g.,detection,biological imaging,and optical devices）due to their good optical properties.However,there is a problem of insufficient sensitivity when using QDs in fluorescence detection.The quenching effect of resonance energy transfer of gold nanoparticles（AuNP）and the enhancement effect of surface plasmon coupling can significantly affect the fluorescence emission of the QDs.These effects could expand the application range of QDs in fluorescence detection,increase the sensitivity of fluorescence detection,and improve the existing fluorescent probe technology.Herein,we used polymer grafted gold NPs/QDs and silica-coated AuNP-QDs to construct solvent-and temperature-responsive fluorescent probes,and ion imprinting fluorescent probe with specific ion detection ability.（1）Solvent-responsive fluorescence probe:Seed growth method was used to synthesize AuNP of different sizes.Subsequently,a ligand exchange method was used to modify thiol-terminated polystyrene（PS）on the surface of AuNP to prepare Au-PS.The fluorescence emission law of Au-PS/QDs in solution blend system and thin film fluorescence detector have been investigated.In addition,the ordered Au-PS/QDs composite film was prepared by self-assembly at the gas-liquid interface.The relationship between the Au-PS/QDs ordered packing structure and the fluorescence emission law has been studied.Moreover,the responsiveness of the ordered Au-PS/QD composite film to organic solvents has been explored.The results show that the PS chains can adsorb organic vapor to change the interparticle distance between AuNP and QDs,and the fluorescence intensity changes significantly,thereby realizing effective detection of organic solvents.（2）Temperature-responsive fluorescence probe:AuNP was synthesized by hydrothermal method.Subsequently,Poly（N-isopropylacrylamide）（PNIPAM）was grafed on the surface of AuNP using a ligand exchange method to prepare PNIPAM-modified AuNP（Au-PNIPAM）.Furthermore,the AuNP-PNIPAM-QDs composite fluorescent probe was prepared by amide reaction,through the amino group of QDs and the carboxyl group of Au-PNIPAM.The results show that the fluorescent probe has excellent temperature responsiveness in aqueous solution.As the temperature increases,the polymer chain shrunk and the distance between the QDs and the AuNP was reduced.Consequently,the fluorescence decreases significantly.In addition,St?ber method was used to prepare silica-coated AuNP with good stability（AuNP@Si O₂）.Furthermore,the method of free radical polymerization was used to graft PNIPAM and some acrylic monomer on the silica shell（AuNP@Si O₂-PNIPAM）,and the QDs were linked by amidation reaction.Finally,the silica-coated AuNP-QDs composite fluorescent probe（AuNP@Si O₂-PNIPAM-QDs）were successfully prepared.The results show that the fluorescent probe has good temperature responsiveness,water solubility and biocompatibility,which could broad application prospects in biological applications.（3）Ion imprinted fluorescence probes:AuNPs were synthesized by seed growth method and then St?ber method was used to prepare silica-coated AuNP with good stability（AuNP@Si O₂）.Amino groups were modified on the surface of AuNP@Si O₂,and then reacted with QDs with carboxyl groups to prepare composite fluorescent NPs（AuNP@Si O₂-QDs）.Then,the copper ion imprinted polymer was polymerized on the surface of the fluorescent NPs to prepare the silica-coated AuNP-QDs composite fluorescent probe（AuNP@Si O₂-QDs@IIP）.The probe can achieve specific detection of copper ions.Compared with QDs@IIP,the detection limit was reduced by about 45% after adding AuNP.