Synthesis And Bioapplications Of Nanocomposites Based On Rare Earth Upconversion Luminescent Materials And Noble Metal Materials

Recently,the application of nanomaterials in cancer diagnosis and treatment has become the focus of attention and research.In order to achieve better diagnosis and treatment results,multifunctional nanoplatform are emerging.The construction of this new system is based on the research and development of multifunctional nanocomposites,which can simultaneously realize the diagnosis and treatment of tumors.In this dissertation,lanthanide-doped upconversion nanoparticles?UCNPs?were successfully synthesized by high-temperature thermal decomposition methods,and their luminescence properties and magnetic resonance imaging capabilities were studied in detail.After proper surface modification and functionalization,the potential biological applications of nanocomposites were explored.A novel composite nanoplatform based on noble metal nanomaterials was constructed for enhanced photothermal/photodynamic tumor therapy,and the mechanism of cell apoptosis was studied in detail.The main contents are summarized as follows:?1?The absorption spectrum of the photosensitizer Ce6 overlapes with the emission spectrum of NaErF₄@NaGdF₄@NaDyF₄ in the visible light region.In view of this,an 808 nm activated up-conversion nanoplatform UCNPs-Ce6 was designed.The high concentration of Er³⁺activator?100 mol%?in UCNPs converts the 808 nm NIR light to the visible light at 654 nm and the near-infrared light at 1530 nm.Visible light at 650 nm activates the photosensitizer Ce6 and produces singlet oxygen,while light at 1530 nm can be used for short-wave infrared?SWIR?imaging with deeper tissue penetration.At the same time,due to the presence of NaGd F₄/NaDyF₄ shells,the platform also showed a contrast enhancement effect on T1/T2 dual-mode imaging.The nanoplatform is promising for multimodal imaging guided PDT treatment.?2?A new composite nanoplatform Pt-Ce6 based on noble metal nanomaterials was constructed for enhanced PDT/PTT combined therapy of tumors.The composite nanoplatform not only acts as a highly efficient catalase mimic to catalyze the decomposition of excess H₂O₂ in tumors to produce O₂ to relieve hypoxia and improve PDT efficiency,but also acts as a NIR-II photothermal conversion agents?PTA?to convert light energy into thermal energy under 1064 nm laser irradiation for PTT.Reactive oxygen species?ROS?produced by Pt-Ce6 under 650 nm laser irradiation induces cell apoptosis through a mitochondrial-mediated pathway?endogenous?.Cell and animal experimental results show that the PDT and PTT are effectively integrated to enhance significantly the treatement efficiacy owing to the excellent catalytic capacity and photothermal conversion ability of Pt-Ce6.Moerover,the synergistic treatment effect is better than single PDT or PTT treatment.