Tumor In Vivo Fluorescence Imaging And Photodynamic Therapy Based On Nanomaterials

Cancer is the second largest threat to human health in the twenty-first century Therefore, the early diagnosis and treatment of cancer is the focus problem of cancer research and clinical diagnosis. Recently, the functionalized nanomaterials, including the nanomaterials modified with biomolecular and the nanomaterials doped with drug and biomolecules, have been applied wildly. Especially, the development of the functionalized nanomaterials which have great biocompatible, specific targeting, good optical characteristics and effective treatment is more necessary and important for cancer imaging diagnosis and treatment. Aiming at the direction of the functionalized nanomaterials for cancer imaging diagnosis and treatment in vivo, preparation of novel near-infrared fluorescent nanomaterilas have been studied, and then these novel near-infrared fluorescent nanomaterilas have been further applied to the tumor fluorescence imaging and photodynamic therapy in vivo. The three parts of the thesis are as follows.1. Study on the preparation of the MB-encapsulated PSiNPs and its application for in vivo fluorescence imagingThe MB doped phosphonate-terminated silica nanoparticles have been synthesized by the controlled synchronous hydrolysis of tetraethoxysilane and trihydroxyl silyl propyl methyl phosphonate in the water-in-oil microemulsion. The stability and leakage of the MB-encapsulated PSiNPs in water, PBS and serum have been investigated, respectively. Then, the feasibility of the MB-encapsulated PSiNPs for in vivo fluorescence imaging and the biodistribution of the MB-encapsulated PSiNPs in vivo were demonstrated. It was found that the fluorescence of MB-encapsulated PSiNPs was very stable in water, PBS and serum, respectively. And the dye leakage of the MB-encapsulated PSiNPs in water, PBS and serum was few. The in vivo fluorescence imaging demonstration showed that the localization injected with suspensions of MB-encapsulated PSiNPs subcutaneously (44 mg/ml) emitted strong fluorescence, and the localization with suspensions of MB-encapsulated PSiNPs subcutaneously (4.4 mg/ml) also produces a detectable signal. Whole body images of MB-encapsulated PSiNPs intravenously injected mice with 200 ml of MB-encapsulated PSiNPs (44 mg/ml) demonstrated that the whole body of the mice emitted NIR fluorescence and most of the MB-encapsulated PSiNPs in mice were accumulated in RES such as live and spleen. The MB-encapsulated PSiNPs could pass the renal excretion. All the results proved that the MB-encapsulated PSiNPs was a promising NIR nano-agent for in vivo imaging.2. Study on the gold nanoclusters for tumor fluorescence imaging in vivoThe fluorescent gold nanoclusters (AuNCs) has been prepared by selecting BSA as the scaffold and reducer. The optical characteristics of the AuNCs, biocompatibility and feasibility as a fluorescent agent for in vivo fluorescence imaging have been investigated. Base on the results, the targeting fluorescence imaging in vivo for tumor by the AuNCs was demonstrated using the Hela and MDA-MB-45 tumor xenograft as models. The results showed that the photostability was higher than the conditional dyes such as Cy3 and Rodamin. The fluorescent intensity was higher than 80% of the original after the irradiated for 10min. Through the body weight change analysis, results display that the body weight of the mice administrated with AuNCs has not been changed obviously by comparing with the control mice injected with PBS. The fluorescence imaging signal of the AuNCs injected subcutaneously, muscle injection and tail vein administrated can be well spectrally distinguished from the background with emission wavelength of about 710 nm. The uptake of AuNCs by the reticuloendothelial system is relatively low by comparing with other nanoparticles based contrast imaging agents due to the ultrasmall hydrodynamic size (-2.7 nm). Using MDA-MB-45 and Hela tumor xenograft models, in vivo and ex vivo imaging studies show that the ultrasmall NIR AuNCs are able to highly accumulate in the tumor area, thanks to the enhanced permeability and retention (EPR) effect. And the tumor-to-background ratio is about 15 for 6 h postinjection. The results indicate that the ultrasmall NIR AuNCs appear as very promising contrast imaging agents for in vivo fluorescence tumor imaging.3. Study on the photodynamic therapy (PDT) for the tumor using MB-encapsulated PSiNPsMethylene blue (MB) is not only a fluorescent agent emitting NIR fluorescence for in vivo imaging, but also a phenothiazinium photosensitizer for photodynamic therapy. Based on the first chapter, the PDT for tumor in vivo using the MB-encapsulated PSiNPs has been investigated. The singlet oxygen generation was detected by a chemical method using the DPBF as a detector. And the protection of MB from reduction by the enzyme was verified. The concentration of MB-encapsulated PSiNPs and exposure time for PDT was optimized. Furthermore, we investigated the fluorescence imaging and PDT treatment to the tumor in vivo using the MB-encapsulated PSiNPs. The results showed that the singlet oxygen-generation of the MB-encapsulated PSiNPs was 0.049, and the silica nanoparticle could effectively prevent the MB from reduction by the enzyme. The rate of death of the cance cells was 90% under the optimal treatment with nanoparticles concentration of 1mg/ml and exposure time of 45min. The results of the fluorescence imaging and PDT treatment to the tumor in vivo demonstrated that the MB-encapsulated PSiNPs was effective for the tumor fluorescence imaging and could treat the tumor through PDT with the light under the guidance of the fluorescence imaging.