Research On The Preparation And Application Of Functional Composite Materials Based On Up-conversion Fluorescent Nanoparticles

Upconverting fluorescent nanomaterials?UCNPs?are novel fluorescent materials that absorb long-wavelength,low-energy,near-infrared light and emit long-short-wavelength,high-energy ultraviolet-visible light.Compared with traditional fluorescent materials,UCNPs have many excellent features,such as photo-stable photochemical properties,long fluorescence lifetime,low toxicity,high tissue penetration depth,almost no damage to biological tissues,zero background fluorescence,high sensitivity of biological imaging,etc.UCNPs are used for bio-fluorescence imaging,nuclear magnetic imaging,CT imaging and biosensor design.Metal-organic framework materials?MOFs?are three-dimensional skeleton crystalline materials formed by coordination of metal ions as central ions through coordination bonds with organic ligands,also known as porous polymers.MOFs materials have the advantages of porous,large specific surface area,good biocompatibility,almost no toxicity,high drug-loading capacity,and are often used as drug carriers for drug transportation.In this paper,we have developed a dual-function therapeutic system with bioimaging and drug controlled release,based on UCNPs materials with bioimaging properties,combined with different materials to combine multi-functional nanocomposites.It alleviates the disadvantages of uneven distribution of drugs in traditional treatment methods,poor pharmacokinetics,and improves the efficiency of cancer treatment.The specific research contents are as follows:1.The upconversion fluorescent nanoparticles and metal-organic framework materials?MIL-53?were successfully combined to form multifunctional therapeutic system UCNPs@MIL-53 for bioimaging and drug release properties through thermal decomposition,in situ growth and self-assembly techniques.The UCNPs NaYF₄:Yb,Er@NaYF₄:Nd are excited by near-infrared light of 808 nm to reduce damage to normal tissues,and have high tissue penetration depth and imaging sensitivity for bioimaging.The nanocomposite achieves DOX loading through hydrogen bonding interactions between MIL-53 and the drug molecule DOX.In addition,we used PEG-FA to modify the surface of the nanocomposite to improve its biocompatibility and target tumor sites.Therefore,we have designed a multi-functional treatment system that can simultaneously achieve variety of functions such as bio-imaging,targeted drug delivery and lesion localization,showing good therapeutic results.2.An Er³⁺-rich red emission upconverting fluorescent nanoparticle NaErF₄:Tm?0.5 mol%?@NaYF₄ was prepared by thermal decomposition method.Er³⁺ions can act as both sensitizers and activators,and high energy transfer between Er³⁺ions can inhibit the effect of concentration quenching on surface coating.A small amount of Tm³⁺can further enhance the up-conversion luminescence and have higher imaging sensitivity.Then,fluorescent nanocomposite NaErF₄:Tm?0.5 mol%?@NaYF₄@ZIF-8 was obtained by coordination of 2-methylimidazole with NaErF4:Tm?0.5mol%?@NaYF₄ adsorbed by Zn²⁺.The zeolitic imidazolate framework material?ZIF-8?has high drug loading,biodegradability and PH responsiveness consistent with the tumor microenvironment,and is used for controlled release of drug molecules.This achieves a versatile cancer treatment system.3.I prepared an cerium(Ce³⁺)-doped down-converted luminescent rare earth nanocrystal that is a novel and effective fluorescent nanoprobe.Ce³⁺doping inhibits the upconversion path while increasing down-conversion by⁹ times to produce bright 1550 nm luminescence at 980 nm excitation.In vivo fluorescence imaging?NIR-IIb window?in the near-infrared region of 1500-1700 nm has high spatial resolution,deep tissue penetration due to suppressed scattering of long-wavelength photons and large fluorophore Stokes shift.Our findings lay the foundation for a new generation of multifunctional biomedical nanomaterials that advance disease surveillance based on advanced infrared imaging technology.