Optimization Of Preparation Conditions And Application Of Up-conversion Nano Fluorescent Probe Based On NaYF₄

In recent years,the preparation and application of fluorescent probes has been a research hotspot in the field of biochemical analysis.The upconversion fluorescent nanoprobes doped with rare earth ions have important research significance in the fields of biomolecular labeling,biosensing and photodynamic therapy due to their advantages of long luminous life,good photostability and low biotoxicity.In the research on the synthesis of upconversion nanocrystals,it is not uncommon to study the upconversion fluorescent materials based on NaYF₄.The controllable synthesis and surface functionalization of upconversion nanocrystals based on NaYF₄with good fluorescence properties and morphology are important prerequisites for its application in the fields of biology and medicine.In this paper,NaYF₄is used as the matrix to investigate the effect of the change of synthesis conditions on its fluorescence properties and morphology.Lanthanide rare earth doped upconversion nano-luminescent probes are prepared by surface modification and further tested on the actual samples.The main contents are as follows:The NaYF₄:Yb³⁺/Nd³⁺/Tm³⁺upconversion nanoparticles are prepared by thermal coprecipitation method.the morphology,particle size and luminescence properties of the nanoparticles are characterized by scanning electron microscopy,transmission electron microscopy,x-ray diffraction and fluorescence spectroscopy.Furthermore,the effect of that ratio of each dope ion,the surfactant in the experimental conditions for synthesize the nano-particles,the reaction temperature and the reaction time on the morphology and the luminescent property of the nano-particles are also discussed,and the optimal preparation conditions are obtained,which lays a foundation for the subsequent synthesis of the nano-fluorescent probe.Then,the NaYF₄:Yb³⁺/Nd³⁺/Tm³⁺upconversion nanoparticles are surface modified,and silicon dioxide is successfully coated on the surface of the particles.Further,the ternary europium complex dibenzoylmethane(DBM)₃-phenanthroline(phen)is introduced onto the surface of silicon dioxide,and then folic acid(FA)is bonded to synthesize a set of upconversion luminescence and common fluorescence imaging nanoprobe,and lay a foundation for further fluorescence imaging detection.In order to obtain better fluorescence performance,Fe³⁺-doped upconversion nanoparticles(UCNPs:Fe³⁺)are prepared by doping transition metal iron into the upconversion nanoparticles NaYF₄:Yb³⁺/Nd³⁺/Tm³⁺,which enhanced the fluorescence properties of the nanoparticles.Furthermore,the experimental conditions are optimized,and the morphology,particle size,luminescent properties and the ratio of various doped ions are discussed.After that,the nanoparticles are modified by amino group,and curcumin,a natural chemical substance,is used as fluorescence signal indicator,and mixed with UCNPs:Fe³⁺to form a nano system,which is applied to the determination of fluoride ion concentration in actual samples.