Synthesis And Application Of Rare Earth Nanocrystalline/noble Metal Composite Fluorescent Materials

With the continuous development and integration of biotechnology and nanotechnology,the nanobiomedicine has received more and more attention.In particular,rare earth doped nanocrystals have been widely used in monitoring of biological small molecule glucose.In this paper,different rare earth doped nanocrystals were used to compound with noble metals,and established a fluorescence assay for rapid glucose detection.This method has the advantages of simple operation,wide detection range and lower detection limit.The main contents are as follows:（1）NaYF₄ is the substrate materials with the highest fluorescence efficiency for rare earth ion so far.NaYF₄:Eu³⁺and NaYF₄:Eu³⁺@Ag composite nanoparticles was successfully synthesized via a the trisodium citrate-assisted hydrothermal synthesis method,and the luminescence properties of the samples were studied.When the the concentration of Eu³⁺ions was 20%,the emission intensities were the strongest.In addition,the absorption spectrum of Ag NP_S are well overlapped with the emission peaks of Eu³⁺ions.The immobilization of Ag NPs onto NaYF₄:Eu³⁺was performed by using trisodium citrate as a coupling and reducing agent.The composite nanostructure was formed by NaYF₄:Eu³⁺as core layer and Ag NPs as shell layer.We have developed a NaYF₄:Eu³⁺@Ag composite nanocrystals for rapid monitoring of glucose levels,because the shell layer can effectively absorb the energy of core layer nanocrystals.In the presence of glucose,Ag NPs is quickly oxidized decomposed into Ag⁺by H₂O₂,which accompanied by down-shifting NaYF₄:Eu³⁺luminescence recovery.（2）Herein,different rare earth doped BaWO₄ and BaWO₄@Au composite nanocrystals were synthesized by solvothermal method.With the help of experiment and density functional theory simulation data,the replacement of Ln³⁺ions in BaWO₄nanocrystals was studied.The luminescent properties of the sample were studies systematically,which were used to monitor glucose levels.The designed scheme is based on the fluorescence quenching and recovery process of Ln³⁺ions caused by energy transfer between Au NPs and BaWO₄:Ln³⁺.The detection limit is 3.1 nmol/L in the glucose concentration linear range of 0-0.501μmol/L.