Research On The Preparation Of Water-soluble Up-conversion Rare Earth Fluorides And Their Optical Properties And Biological Applications

In recent years,rare earth upconversion luminescence materials have attracted the attention of researchers,and are considered as a new generation of fluorescent probes for biological research.In particular,under continuouswave excitation at 980 nm,lanthanide(Ln)-doping upconversion nanoparticles(UCNPs)exhibit unique upconversion luminescence(UCL)properties,which can avoid the disadvantages of the traditional fluorescent materials,and can effectively reduce the autofluorescence of biological tissue in biological applications.As a promising fluorescent probe,UCNPs have been widely used in many fields,such as biological detection,cell tracking,imaging and so on.In addition,in biological applications,the UCL efficiency is of critical importance because high efficiency can improve the signal to noise ratio when imaging.However,the fluorescence quantum yield of UPNPs is low,which limits its application.Results are as follows:(1)Study on the preparation of YF3:Yb/Er nanocrystals(NPs)and effect of Zn2+/Mg2+doping on the fluorescence properties.Hydrophilic YF3:Yb/Er NPs were prepared by one pot hydrothermal method and showed a special bow-like morphology.The effects of D-serine,F source and temperature on the morphology of the samples were investigated in detail.It was found that the temperature had no effect on the morphology of the samples,but D-serine and F had a great influence and when NH4BF4(or NaBF4)and D-serine were added at the same time we can get the special bow shape.In addition,based on the effect of D-serine on the morphology of YF3:Yb/Er NPs,the effects of different amino acids on the morphology and fluorescence intensity of samples were further studied.The fluorescence intensity of samples was weak when we used D-serine as surface coating agent.Therefore,it is necessary to enhance the fluorescence intensity by doping a certain concentration of Zn2+ or Mg2+ ions.The results show that the maximum fluorescence intensity is obtained when 50 mol%Zn2+or 30 mol%Mg2+ions are doped.The results show that amino acids can be used as surface active agents in the synthesis of nanomaterials.This paper provides a reference for the preparation of water-soluble and biocompatible materials.(2)Effects of Ca2+/Sr2+/Ba2+doping on the physical and fluorescent properties of YF3:Yb/Er nanocrystals.In the YF3:Yb/Er NPs system of D-serine as a surfactant,the effect of the concentration of alkaline earth metal ions(M2+)on the size,morphology and fluorescence properties of the material was investigated,and the related mechanism was analyzed.The size and morphology of YF3:Yb/Er NPs varied with different concentrations of Ca2+,Sr2+or Ba2+ions.At the same time,the upconversion emission spectra of samples with different concentrations of M2+ ions were analyzed.It is found that the maximum visible green light(544 nm)and red light(658 nm)emission can be observed in YF3:Yb/Er/30 mol%Ca2+(30 mol%Sr2+and 20 mol%Ba2+)NPs.(3)Preparation of novel NIR ?-NaGdF4:Yb,Tm@mSiO2NPs fluorescent probe and its application in detection of cancer cells.?-NaGdF4@mSiO2 NPs was prepared.First of all,the hydrophobic beta-NaGdF4NPs was synthesized by high temperature thermal decomposition method.Then,hexadecyl trimethyl ammonium was used as a modifier to dissolve it in water.Then,the NaGdF4@mSiO2 NPs were synthesised by sol-gel method.Finally,Cy-S-Ph-NH2 was successfully loaded into NaGdF4@mSiO2 NPs by physical adsorption method.Cy-S-Ph-NH2 has a strong UV absorption at 800 nm,which can overlap with the near infrared emission light of NaGdF4@mSiO2 NPs at about 808 nm.So the energy resonance can be realized and fluorescence of NaGdF4@mSiO2 NPs at about 808 nm will be quenched.Based on the light induction of Cy-S-Ph-NH2,toxic singlet oxygen can be released under the irradiation of 808 nm laser.And the fluorescence signal can be restored at the same time.It can be seen that the delivery of Cy-S-Ph-NH2-?-NaGdF4@mSiO2 complex into cancer cells can simultaneously detect and treat cancer cells.These materials provide a new platform for biological detection and disease treatment.In addition,this method can also be used to construct other multifunctional nano carriers,such as biological imaging and drug delivery.