Synthesis And Theranostic Applications Of Several Rare Earth Doped Nanocrystals

In recent years,with the development of nanomedicine,novel multifunctional theranostic nanoplatforms have brought new hope for early diagnosis and accurate treatment of cancer.Due to larger atomic numbers and abundant optical,electrical,magnetic properties of rare earth elements.Rare earth doped upconversion nanomaterials show great promise in multimodal imaging,which have attracted wide attention in the field of biological imaging.Through the design of porous structure or functional modification,rare earth doped nanomaterials can be used as carriers of anticancer drugs and other theranostic agents,thus building a multifunctional theranostic nanoplatform,which can achieve accurate diagnosis and efficient treatment of cancer.In this dissertation,we designed and synthesized novel rare earth doped porous nanomaterials,which could be used as drug carriers for cancer imaging and therapy.Besides,novel multifunctional nanohybrids were constructed by integrating UCNPs and photothermal theranostic agents,exhibiting great potential in multimodal imaging-guided photothermal therapy(PTT).The main contents are shown as follows:1.Monodisperse YF3 and YOF sub-microspheres with different porous structures were synthesized by a novel self-sacrificing template method using amorphous Y(OH)CO3·xH2O sub-microspheres as templates.Through a series of orthogonal experiments,it was found that the concentration of initial HF in the reaction system is the main reason causing different porous structures of YF3 and YOF,In addition,the method was successfully extended to the synthesis of other porous rare earth fluorides(GdF3,LuF3)and YOX(X=Cl,Br).Besides,we systematically investigated the luminescence properties including down-/upconversion and Ce3+-Tb3+energy transfer of YF3:Ln3+by doping different activators.2.A facile aqueous-based approach was designed towards uniform porous/hollow YVO4 submicro-ellipsoids using layered yttrium hydroxide(LYH)as a precursor.The time-dependent morphological evolution revealed a rapid assembly-Ostwald ripening growth process.Also,a detailed structural analysis indicated the high structural matching of[001]LYH//[110]YVO4.Moreover,we systematically investigated the influences of experimental variables(temperature,pH,and Na+ concentration)on the morphology and size evolution of the final products.In addition,we also studied the luminescence properties of YVO4:Ln3+(Ln=Eu,Sm,and Dy)by multicolor emissions.3.Polyacrylic acid(PAA)capped porous BiF3 sub-microspheres were synthesized by a simple one-pot reaction approach.The Ln3+doped(Ln=Yb/Er,Yb/Ho,Yb/Tm)BiF3 exhibited characteristic upconversion luminescence.And the BiF3:Ln3+ material had smaller size and larger BET specific surface area and pore volume than that of undoped BiF3.The PAA-capped BiF3:Yb,Er porous nanospheres exhibited good biocompatibility and pH-responsive drug release capacity,which could effectively alleviate the side effects of DOX.Moreover,BiF3:Yb,Er showed efficient CT imaging and ideal optical temperature sensing property.Therefore,BiF3:Yb,Er porous nanospheres have great potential in temperature sensing,pH-responsive drug delivery and CT imaging.4.Rare earth doped upconversion nanoparticles(UCNPs)with core-shell structure were synthesized by high temperature pyrolysis process.Then,multifunctional UCNPs@Bi@SiO2 nanohybrid was constructed using UCNPs as building blocks.The synthesized UCNPs@Bi@SiO2 combined the unique optical properties of UCNPs with the excellent photothermal conversion and CT imaging capabilities of Bi nanoparticles.More importantly,the easy oxidation and poor photothermal stability of Bi nanomaterial were effectively solved by the dense SiO2 shell in the outermost.Besides,we demonstrated at the cellular level that UCNPs@Bi@SiO2 has great potential in UCL/CT imaging-guided photothermal therapy(PTT).5.UCNP-Bi2Se3 upconverting nanohybrid was synthesized by a simple in situ growth strategy based on the unique advantages of core-shell structured UCNPs in biological imaging and the efficient photothermal conversion ability of Bi2Se3 nanoparticles.In vitro assays demonstrated that UCNP-Bi2Se3 exhibited low cytotoxicity,obvious UCL signal and efficient cancer cell ablation,achieving UCL imaging and PTT under single 808 nm near-infrared(NIR)laser irradiation.Besides,the existence of Bi and Lu endowed UCNP-Bi2Se3 nanomaterial with good CT imaging ability.Therefore,UCNP-Bi2Se3 nanohybrid shows great promise in the field of non-invasive diagnosis and treatment.