Construction Of Light Functional Nanomaterials And Its Application In Biological Imaging And Tumor Therapy

Rare-earth Upconversion nanophosphors (UCNPs) are a novel class of luminescent bio-labels and has been widely applied for in vivo fluorescence imaging. As an imaging agent in living body, it is of great importance that the biocompatibility should be thoroughly investigated; on the other hand, the metabolic pathway is another research focus of UCNPs. Aiming the above problems, this thesis studies the toxicity of UCNPs to plants and animals, the blood circulation time of ligands modified UCNPs in mice via intravenous injection, and the application of nanoparticles in photothermal cancer therapy; the work contains three parts as follows:1. Upconversion Nanoparticles Dramatically Promote Plant Growth without ToxicityWe investigate the effects of UCNPs on plant development using mung beans as a model. Incubation at a high UCNPs concentration of100μg/mL led to growth inhibition, while a low concentration of10μg/mL promoted their development. Confocal imaging showed that UCNPs accumulated in the seeds and were transferred from seeds and roots to stems and leaves through the vascular system. Quantitative study by radioanalysis showed the distribution of UCNPs in the plant on the5th day after incubation decreased in the order (root> seed> leaf> stem). After UCNPs-treated bean sprouts were orally ingested by mice, UCNPs were completely excreted with feces, without absorption ofresidual amounts. Histology and hematology results showed no detectable toxic effects of UCNPs-treated mung beans on exposed mice.2. Polyphosphoric Acid Capped Radioactive/Upconversion Nanoparticles for in vivo Blood Pool ImagingWe report on difunctional radioactive and upconversion nanoparticles (UCNPs) coated with polyphosphoric acid-elhylenediamine tetra methylenephosphonic acid (EDTMP) for a single-photon emission computed tomography (SPECT) blood pool imaging application. The structure, size and surface zeta potential of the EDTMP-coated nanoparticles (EDTMP-UCNPs) were verified using transmission electron microscopy and dynamic light scattering. Injections of radioactive element samarium-153-labeled EDTMP-UCNPs (153Sm-EDTMP-UCNPs) into mice revealed superior circulation time as compared to control nanoparticles coated with citric acid (cit) materials (153Sm-cit-UCNPs) and the complex EDTMP-153Sm. The reason for thelong circulation of the EDTMP-UCNPs may be attributed to adhering to red blood cells (RBCs). The in vivo toxicity results indicated that mice intravenously injected with EDTMP-UCNPs for blood pool imaging did not suffer from any significant toxic effects. The studies provide preliminary validation for the use of EDTMP-UCNPs for blood pool imaging.3. PhthaIocyanine@HoIlow Silica Nanoparticles for Highly Effective in Vivo Near-Infrared Photodynamic and Photothermal Therapy of CancerIn this chapter, we employed the hollow silica nanospheres (HSNs) which have larger pore volume to transport water-insoluble photosensitizers into biocompatible. The Pc@HSNs has proven stable in PBS and RPMI1640nutrient solution. The Pc@HSNs solution exhibits highly efficient dual photodynamic therapy (PDT) and photothermal therapy (PTT) effects upon the irradiation of near infrared laser. The dual phototherapeutic effect of Pc@HSNs is proven to enhance cytotoxic efficiency according to both in vitro and in vivo experimental results. This novel multifunctional nanomaterial may be useful for near-infrared PTT/PDT in various cancers.4. Yolk-shell Structured Upconversion Nanoparticles Loaded Phthalocyanine for Targeted Imaging and Photothermal Therapy of CancerIn this chapter, we optimized the previous system. First, phthalocyanine was modified as palladium phthalocyanine, and its maximum absorption peak is located at730nm, with a high absorptivity. Then yolk shell structured UCNPs@SiO2(YSUCNPs) were used to load palladium phthalocyanine (PdPc@YSUCNPs). Such materials can be used for both imaging and photothermal therapy. The phototherapeutic effect of PdPc@YSUCNPs is proven to enhance cytotoxic efficiency according to both in vitro and in vivo experimental results. The experimental results show that through modification of PEG on the surface of YSUCNPs PEG, material can be passive targeting to the cancer. This multifunctional nanomaterial may be useful for near-infrared PTT cancer.