Preparation And Characterization Of Precious Metal-Doped Upconversion Rare Earth Nanomaterials And Their Application In Tumor Diagnosis And Treatment

In this paper,the Coprecipitation Hydrothermal Solvothermal Solvothermal（CHSS）method was used to prepare upconversion nanomaterials doped with silver/gold nanoparticles(Ag-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄ and Au-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄).On the basis of clarifying the doping mechanism of silver/gold nanoparticles,the effects of their doping on the structure,morphology and performance of upconversion nanomaterials were compared and analyzed.At the same time endow it with photothermal properties,and explore its application in tumor multimodal imaging and therapy.Firstly,the Ag-Na YF₄:Yb³⁺/Er³⁺materials with different doping amounts of silver nanoparticles were prepared by co-precipitation-hydrothermal method,and the doping behavior and mechanism of silver nanoparticles were discussed.The morphological structure and performance were analyzed and characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）,and liquid fluorescence spectroscopy（PL）,respectively.The results show that the doping of silver nanoparticles makes the upconversion nanomaterials change from porous hexagonal nanorods to hexagonal nanorods with a smooth surface,and enhances the luminous intensity of the upconversion nanomaterials.And enhance the luminescence performance of the upconversion nanomaterials,the quantum yield results show that the doping of silver nanoparticles enhances the luminescence performance by 13 times.Secondly,Ag-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄ and Au-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄ upconversion nanomaterials with core-shell structures with sliver nanoparticles and gold nanoparticles as cores and Na YF₄:Nd³⁺@Na Gd F₄ as shells were prepared by CHSS method,respectively.On this basis,their surfaces were modified with DSPE-PEG2K.Cytotoxicity experiments show that the modified upconversion nanomaterials have good colloidal stability and biocompatibility.Photothermal conversion experiments demonstrated successful endowment of upconversion nanomaterials with photothermal properties,enabling them to undergo photothermal therapy（PTT）of tumors;singlet reactive oxygen species（ROS）testing and flow cytometry results demonstrated their photodynamic therapy（PDT）tumor possibility.On the basis of the above experiments,the imaging capabilities of Ag-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄ and Au-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄ in biological imaging were compared and analyzed through animal experiments.The test results of fluorescence imaging（UCL）,computed tomography（CT）,magnetic resonance imaging（MRI）,and photoacoustic imaging（PAI）show that these two upconversion nanomaterials have excellent biological imaging capabilities and the imaging of Au-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄ ability is better than Ag-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄.Simultaneous multimodal imaging technology enables tumor visualization.Finally,an animal tumor model was constructed,and Au-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄-DSPE-PEG_2K was used to treat tumors in mice.PTT treatment was performed with near-infrared light with a wavelength of 980 nm alone;PDT treatment was performed with near-infrared light with a wavelength of 808 nm alone;PTT/PDT synergistic treatment was performed with near-infrared light with a wavelength of 980 nm and near-infrared light with a wavelength of 808 nm.By comparing the 15-day treatment results,it was found that the effect of PTT/PDT synergistic treatment of tumors was far greater than that of any single mode of treatment.It also shows that Au-Na YF₄:Yb³⁺/Er³⁺@Na YF₄:Nd³⁺@Na Gd F₄-DSPE-PEG_2K has efficient and rapid tumor treatment ability.Combined with its bioimaging capabilities,it is expected to realize the integration of tumor diagnosis and treatment in the true sense.