Preparation And Fluorescence Properties Of Rare Earth (La³⁺,Nd³⁺,Eu³⁺)-doped Bioimaging Nanomaterials

Research on biological science has been deep into the cell and molecule level.In recent years,with the rapid development of nanotechnology,biotechnology and material technology,rare earth luminescent nanomaterials have been widely used in fluorescence imaging as a new bioluminescent marker material.Compared with traditional fluorescent probes（such as organic fluorescent dyes and semiconductor quantum dots）,rare earth luminescent nanomaterials have the advantages of long fluorescence lifetime,narrow emission band,strong Stokes shift,strong photochemical stability and small bio-toxicity.So rare earth luminescent nanomaterials have great potential in fluorescence immunoassay,biomolecule labeling,luminescence resonance energy transfer and cellular imaging.The preparation and performance of rare earth luminescent nanomaterials for biofluorescence labeling have attracted researchers’ attention.Rare earth nanomaterials used in biological imaging should be hydrophilic,small in size（typically less than 50 nm）,with active groups on the surface to increase biocompatibility and facilitate further attachment of biomolecules.Therefore,in this paper,based on the surface modification by water-soluble polymer,a series of ultraviolet-visible and near-infrared-near-infrared rare earth luminescent nanomaterials with different morphologies and sizes were prepared by hydrothermal method.Fluorescence probes were incubated with HeLa cells to test the cellular imaging and toxicity.The specific work of this paper is as follows:（1）La F₃:Eu（50 mol%）@PAA modified by polyacrylic acid（PAA）was optimized by changing the amount of polyacrylic acid,reaction temperature and reaction time respectively.The results show that the nanoparticles showed great dispersion stability and photostability in PBS.（2）La F₃:Eu（50 mol%）@PAA nanoparticles were subjected to cell experiments.After changing the incubation time and concentration,the optimum culture time and cell incubation time were obtained.At the wavelength of 515 nm,the nanoparticles emitted red fluorescence and the fluorescence was concentrated inside the He La cells.The results show that the nanomaterials have low toxicity to HeLa cells.The nanosized particles can be used as biosynthesis as UV-visible water-soluble nanomaterials.（3）LaF₃:Nd@FA modified by folic acid（FA）was synthesized by one-step hydrothermal method.The nanoparticles were about 10 nm in size.The FA molecules were linked to the surface of the nanoparticles,FT-IR,fluorescence spectroscopy（PL）and lifetime attenuation were consistent with those reported in the literature,and the dispersibility and stability were good in XRD and standard colorimetric cards.Being incubated with HeLa cells,high concentration of LaF₃: Nd（3 mol%）@FA nanoparticles showed low toxicity to cells.The results show that the nanoparticles can be used as near infrared（NIR-NIR）water-soluble nanomaterials for biological imaging.