Preparation Of High-aspect-ratio Gold Nanorods And Cytotoxicity Research Of Gold Nanoparticles

Since the21st century, the rapid and great progress in nanotechnology made itbecome one of the major driving forces of global economic development. It isexpected that nanotechnology can not only promote the upgrading of traditionalindustries, but also improves the quality of human life fundamentally. The main objectof the nanotechnology research is materials with the size between1nm and100nm.The physical and chemical properties of nanoscaled materials will become totallydifferent from bulk materials. Biological effects of nanomaterials in the living bodyand the mechanism of these biological effects had become a hot field of scientificresearch. Previous reports still did not give a clear exposition and interpretation. Forthe further study of nanotechnology and nanomaterials, problems including biologicaleffects and safety issues of nanomaterials become the focus of attention.Gold nanoparticles with unique optical and thermal properties were widely usedin biomedical field. Especially, rod-like gold nanoparticles possess tunable surfaceplasmon resonance absorption peak, due to the controllable aspect ratio, which can beadjusted to the near infrared region and light with a wavelength at the near infraredregion is generally regarded transparent to the biological tissues. Therefore goldnanorods have shown great promising prospect in photothermal therapy, drug deliveryand diseases treatment. However, with the deep research on the adverse effects of avariety of nanomaterials to human and environment, biosafety issues of goldnanoparticles has also been a concern.On the basis of synthesizing gold nanorods with large aspect ratio, this thesis isfocused on the systematic research of the cell biological effects of gold nanoparticles.1. The appropriate density of different cell types is explored when cell viabilityis measured by MTT assay. The toxic effect of105nm,50nm and20nm goldnanoparticle on HeLa, MG-63cancer cells and HaCaT normal cells are determined bythe simple, economic MTT assay. At a large particle concentration range, the goldnanoparticles did not show significant toxic effects to all the three types of cells.2. Based on previous synthesis process of gold nanorods, we chose a three-stepcrystal growth to synthesize high aspect ratio gold nanorods, the aspect ratio of whichis approximately14. The prepared gold nanorods were characterized by UV-visspectroscopy and transmission electron microscopy. Surface charge and hydraulic radius of the gold nanorods were measured. The results showed that the uniform anddispersed gold nanorods can be fast and simply prepared with the three-step seedgrowth method under mild experimental conditions. Finally, the gold nanorods growthmechanism was discussed.3. Surface modification of the gold nanorods with large aspect ratio and thebiological compatibility study. The CTAB molecules on the surface of gold nanorodswere replaced by the MUDA molecules. Functionalized gold nanorods did notdemonstrate a significant toxicity to HeLa cell until the GNR-MUDA concentrationup to600g/mL. GNR-MUDA is internalized by HeLa cells and exists in the form ofaggregates under TEM. The influence of GNR-MUDA in cell adherent, proliferation,intracellular ROS and the cytoskeleton are studied. We found that cells couldnormally attach after incubated with GNR-MUDA, and cell proliferation waspromoted. But the endocytosis of superfluous GNR-MUDA will lead to increasedintracellular ROS and impaired cell skeleton.