Preparation Of Lanthanide Upconversion Nanocomposites And Their Research In Bioimaging

Multifunctional Lanthanide-doped upconversion nanoparticles?UCNPs?have good biocompatibility,no toxic side effects,background-free luminescence interference,easy to combine with other materials,which are widely used in the field of biological imaging and detection,drug delivery and release,cancer diagnosis and treatment.However,most of the emission peaks of conventionally converted nanoprobes applied in bioimaging are not in the near-infrared region,more importantly,owing to the low luminescence efficiency,which hinder their further application.In this dissertation,the lattice of upconversion nanomaterials were controlled by doped Fe³⁺ions,Yb³⁺/Tm³⁺ions to enhance the NIR emission intensity and upconversion luminescence.Multifunctional composite materials have been developed for target biological tissues through UCL/MRI/X-ray bioimaging.The details are as follows:?1?Preparation of Fe³⁺-doped UCNPs composites and their modification by target functional group.With the higher emission efficiency of NaYF₄ as the matrix,the influences of Fe³⁺ion doped with different concentrations on the emission intensity of upconversion luminescence were investigated.Nanomaterials doped with 20%Fe³⁺ions,NaYF₄:Yb³⁺,Tm³⁺,20%Fe³⁺?Y:Yb,Tm,20%Fe?,under the excitation of 980 nm,NIR luminescence emission intensity more 20 times than doped-free.Luminescence enhancement mechanism after Fe³⁺-doped was investigated to show that Yb³⁺-Fe³⁺dimerization complex has formed in materials.A thin layer of NaGdF₄ was coated on the surface of core material,the T₁ weighted relaxation rate reached 3.51 mM^-1S^-1in vitro,which has good T₁ magnetic resonance imaging capability.These results show that the material have high intensity NIR emission at the optimal 20%Fe³⁺-doping concentration,which lays a foundation for subsequent bioimaging.?in chapter two??2?Tumor-specific target bioimaging of UCNPs composites.Fe³⁺-doping effectively enhanced the near-infrared region UCL luminescence efficiency of FA-NaYF₄:Yb³⁺,Tm³⁺,20%Fe³⁺@NaGdF₄?FA-Y:Yb,Tm,20%Fe@Gd NPs?,at the same time,the low biotoxicity and good biocompatibility meet the requirements of bioimaging.Since the dissected organs of mice lack autofluorescence,organ luminescence imaging in vitro can reflect the materials distribution in various organs.After the nanocomposite were tail vein injected to tumor nude mice,luminescence aggregation in the tumor site and the strong MR signals indicated that the material can achieve the UCL/MRI/X-ray trimodal biological imaging.?in chapter three??3?MALDI-TOF-IMS of carrot metabolites.Imaging mass spectrometry?IMS?based on the ability to detect large amounts of molecules in thin tissue sections while achieving spatial distribution of biomolecules,with the help of MALDI-TOF-IMS,in this chapter,the mass spectrometry imaging of carrot was studied.Compared with Bi_0.15Fe_0.15-ZrO₂ nanomatrix and traditional organic DHB,the prepared inorganic Bi_0.15Fe_0.15-TiO₂ nanomatrix has less interference with the matrix peak,and the effect was more significant.A total of 17 molecules in carrot were detected.Using the IMS analyzed the spatial distribution of carrot metabolites.?in chapter four?...