Properties Of Rare Earth Upconversion Nanocomposites With Tumor Microenvironment Response Function

Cancer remains one of the deadliest diseases and causes millions of deaths every year.In recent years,photodynamic therapy?PDT?is one of the important methods in the research of tumor therapy.PDT has three treatment conditions which are photosensitizers,oxygen and light.So only by selecting the appropriate light source and photosensitizers can improve PDT.The preparation of hydrogen peroxide responsive nanomaterials has become a hot research topic,because there is much hydrogen in tumor microenvironment.Compared with visible light,near-infrared light can penetrate tissue at a greater depth,which make it an excellent light source.Upconversion nanoparticles can convert near-infrared light to visible light,thus stimulating photosensitizers.Therefore,upconversion nanoparticles have been widely used in the design of photosensitizers carriers.In the paper,we have designed and synthesized two kinds of rare earth upconversion nanocomposites based on rare earth upconversion nanoparticles.The main results are as following:NaYF₄:Yb,Er@NaGdF₄?UCNPs?has been sythwsized by high temperature pyrolysis methods,and the suface-ligands of UCNPs were oleic acid.UCNPs is coated with a layer of organic dendrimer G4 PAMAM by mercapto-ene and azide-acetylene click reaction.Finally,CTPP has been modified on the surface of PAMAM by esterification reaction.Photosensitizers Ce6 and catalase have been loaded in UCNPs@G4-CTPP.The textural,morphological and structural properties of the composites were carefully characterized by X-ray diffraction,transmission electron microscopy and Fourier Transform infrared spectroscopy.The toxicity of the material to 4T1 cells in vitro and in vivo,as well as the effects of photosensitizer Ce6 and catalase were texted.In order to verify the photodynamic treatment performance of the system,the difference of damage ability of normal cells and diseased tissues during the treatment was studied by using organ section test.Importantly,the Gd³⁺co-doped UCNPs endow the nanomedicine MRI imaging.Heterjunction photosensitizer Fe₃O₄@MIL-100?Fe??FM?was prepared by layer assembly method which the inorganic nanoparticles Fe₃O₄ was used as the core.NaYF₄:Yb,Tm@NaGdF₄:Yb nanoparticles were prepared by high temperature pyrolysis.FMUP was obtained by condensation reaction linking FM and rare earth nanoparticles and modifying PEG.The crystal phase,structure,morphology and luminescence properties of the materials were characterized by X-ray diffraction,fluorescence spectrum and transmission electron microscopy.Through in vitro and in vivo toxicity experiments of FMUP,the results showed that FMUP could perform photochemical and photodynamic synergistic treatment,and effectively inhibit tumor growth.The material showed upconversion fluorescence imaging and CT imaging,which had a great application in the field of biological imaging.