Investigation On Silver/reduced Gralphene Oxide Nanocomposite And Its Cytotoxic Activity Against MCF-7Cells

Graphene oxide (GO) has re-emerged as an intense research interest to its role as a precursor for the cost-effective and mass production of chemically converted graphene (CCG) and graphene-based materials. In this thesis, GO samples with different oxidation degree were synthetized through modified Hummers method by changing their reaction time, respectively. The structure, composition, and disorder parameter of GO were confirmed by means of XRD, FTIR, Raman, and SEM. An one-pot and green synthesis approach had been employed to prepare silver/reduced graphene oxide (Ag/rGO) nanocomposite in the presence of sodium hydroxide at70℃. Parameters in the preparation process, such as reaction temperture and reaction time, were discussed and the potential application of Ag/rGO nanocomposite in cancer photodynamic therapy and photothermal therapy was explored at the same time.Results show that:the structure of origin graphite was damaged completely within oxidation time of1hour at0℃, with the derivation of hydroxyl and epoxy groups on the basal of GO sheets. The degree of oxidation of GO increased over time at0℃, while it changed little at35℃. Within30min at95℃, it showed a significant increase of the degree of oxidation of GO. And carboxyl, carbonyl and alkoxy groups appeared in larger numbers at the edge of GO sheets, which lead to defects and holes on the GO surface. The disorder degree of GO may decrease if the reaction time at95℃was so long, due to the removal of some unstable goups on GO sheets.The Ag/rGO nanocomposite was prepared in an one-pot and green approach in alikaline solution using silver nitrate as precursor and graphene oxide as substrate.Within11min, the small-sized (av.11nm) and highly dispersed silver nanoparticles were supported on reduced graphene oxide sheets. The FTIR and XRD results demonstrates that NaOH accelerated the removal of carboxyl groups on the surface of GO, and Ag+attributed to recover the C=C sp2structure of rGO. Strong interaction may exist between silver nanopaticles and the remaining surface hydroxyl groups in Ag/rGO nanocomposite. The silver crystal growth was influenced by temperature and alkali concentration, rather than the reaction time. While long reaction time attributed to the recover of C=C sp2structure of rGO.In this work, for the first time we studied the behaviors of Ag/rGO nanocomposite in photodynamic therapy under532nm laser and photothermal therapy under NIR light (808nm) to kill MCF-7human breast cancer cell. Ag/rGO nanocomposite has cytotoxicity under irradiation and can be used as cancer therapeutic photosensitizer. The as-obtained Ag/rGO nanocomposite presented effective ability of cancer photodynamic therapy and photothermal therapy.