Temperature Sensing And Biological Application Of Rare-earth Doped Upconversion Luminescent Materials

The upconversion nanoparticles?UCNPs?doped with lanthanide ions possess excellent optical properties based on large Stokes shift under near infrared?NIR?light.In particular,the temperature measurement by fluorescence from UCNPs has been paid more attention due to the urgent need for non-contact thermometer in physical,chemical and biological field.The influence of the different structures and bonding of the hosts on the temperature sensitivities is investigated in details.Furthermore,the as-prepared nanoparticles are used for temperature sensing in liquid environment and synergetic therapy of pthotodynamics therapy?PDT?and chemotherapy to achieve the effective suppression for the growth of tumor tissue.The main works are showed as follows:1.The Y₂O₃,Y₃Al₅O₁₂,LaAlO₃ phosphors with optimum concentrations(Yb³⁺/Er³⁺)are synthetized by sol-gel method.The temperature sensing properties are investigated and the maximum sensitivities are obtained by utilizing the thermal coupled levels(TCLs,²H_11/2/⁴S_3/2)of Er³⁺.Moreover,the relationship between sensitivity and covalent bond is gained through chemical bond theory.2.The Y₂O₃,Y₃Al₅O₁₂,LaAlO₃ phosphors with optimum concentrations(Yb³⁺/Tm³⁺)are synthetized by sol-gel method.It is interesting that the energy gap between TCLs(¹G_4?1?/¹G_4?2?)of Tm³⁺is narrow(³15 cm^-1),the maximum sensitivities of phosphors are acquired at low temperature by using fluorescence intensity ratio technique?FIR?.In addition,the internal temperatures of phosphors are calculated under 980 nm irradiation.All the results provide a good guide for the choices of materials and rare earth ions in biological temperature measurement.3.The monodisperse CaF₂:Yb³⁺/Er³⁺nanoparticles with good biocompatibility and strong fluorescence are prepared by one pot solvothermal method.We pay more attention to the temperature sensing and bioimaging,the endocytosis of Hela cells for nanoparticles is also studied.4.The small sized and enhanced fluorescent CaF₂:Yb³⁺,Er³⁺@NaGdF₄:Yb³⁺@NaGdF₄ nanoparticles with multi-shell structure are synthetized by solvothermal method.In addition,the RBHA?a photosensitizer?and Pt?IV?drug are loaded on the surface of nanoparticles.Finally,the temperature measurement in liquid,bio-imaging in vivo,synergetic therapy of PDT and chemotherapy are come true based on the single nanoparticles.5.The SiO₂ coated Gd₂?WO₄?₃ nanoparticles with uniform distribution are prepared by one pot co-precipitation method for the first time.Subsequently,the Pt?IV?drug is coupling on the surface of nanoparticles through amphiphilic polymer PEI.The oxide nanoparticles are used to temperature sensing and chemotherapy,which broadens the direction for the application of upconversion oxide materials.