Preparation Of Graphene Oxide-based Hybrid Materials And Their Applications In Biological Imaging And Cancer Photothermal Therapy

Since its discovery in 2004, graphene oxide(GO) has been considered as a novel carbon nanomaterial. Due to its superior optical, electrical and thermal properties, GO shows broad research prospects in biomedical and electrochemical fields. Because of the large surface and rich functional groups on the surface, GO can be used as a carrier. The surface of GO nanosheets has been loaded with nanoparticles or macromolecules of specific functions for the applications in biomedical diagnosis and treatment fields. In addition, GO has a strong optical absorption in the near infrared region, so many researchers used GO as a photothermal agent for cancer photothermal therapy and get the desired results. In this thesis, we modified Ba Gd F5 or bismuth selenide nanoparticles on the surface of graphene oxide and further modified with polyethylene glycol(PEG) or polyvinylpyrrolidone(PVP) to increase the biocompatibility of the resulting nanomaterials. The obtained nanomaterials possess biological imaging and photothermal therapeutic functions. Studies of in vivo MR/CT imaging and photothermal tumor therapy have also been carried out with the as-prepared nanomaterials. This thesis is divided into four chapters.The first chapter summarizes the structures, properties, surface modifications of graphene oxide and its applications in biological imaging and cancer photothermal therapy.The second chapter is the research about the preparation, photothermal properties of GO/Ba Gd F5/PEG nanomaterials and their applications in MR/CT imaging and cancer photothermal therapy. GO/Ba Gd F5/PEG nanomaterials were prepared by a solvothermal method, and Ba Gd F5 nanoparticles can be firmly attached on the surface of GO nanosheets. The resulting GO/Ba Gd F5/PEG shows excellent photothermal properties, high photothermal stability, good biocompatibility and low cytotoxicity. GO/Ba Gd F5/PEG shows ideal magnetic resonance(MR) contrast effect and X-ray attenuation property in cellular level or even in the tumor-bearing mice, which indicates that the obtained material is a promising multi-modal biological imaging contrast agent. Finally, we carried out the in vivo cancer photothermal therapy by intravenous injection of GO/Ba Gd F5/PEG and the following 808-nm laser irradiation and obtained ideal photothermal tumor ablation effect. GO/Ba Gd F5/PEG nanomaterials conbine MR, CT imaging and photothermal therapy functions into one system, and they show promising application potential in biomedical fields.The third chapter is the research about the CT imaging and cancer photothermal therapy applications of GO/Bi2Se3/PVP nanomaterials. Ideal CT imaging effect was obtained after intratumoral injection of the material, which reveals that GO/Bi2Se3/PVP material is a promising CT imaging contrast agent. At the same time, the in vivo cancer photothermal therapy experiments were carried out by directly intratumoral injection of the material, and ideal cancer photothermal ablation effect were obtained. Finally, we researched the in vivo toxicity of GO/Bi2Se3/PVP material to the tumor-bearing mice. The GO/Bi2Se3/PVP material show low toxicity after intravenous injection into the mice. Therefore, GO/Bi2Se3/PVP material can be used for bioimaging contrast agent and cancer photothermal therapy.The fourth chapter summarizes the important experimental data and results obtained in this work. Finally, we show the outlooks about the further applications of GO based nanomaterials in the future.