The Optical Properties Of SiO₂@Au Nanocomposites And Drug Release Controlled By Light

The combination of optical technology and nanotechnology has been done in the exploration and application of optical properties of nanomaterials.Gold nanoparticles with controllable localized surface plasmon resonance absorption have been applied in photocatalysis,optoelectronics,biomedicine,biosensor and other aspects of a wide range of applications,because of their unique optical properties.In this thesis,SiO₂@Au nanocomposites with controllable localized surface plasmon resonance absorption peak from the visible region to the near-infrared region were prepared based on the optical properties of gold nanoparticles.Doxorubicin?DOX,a kind of anti-cancer drugs?was successfully loaded on SiO₂@Au nanocomposites.The loaded doxorubicin can be released due to photothermal effect of SiO₂@Au and p H-sensitive effect of SiO₂@Au@DOX.The main results are as follows:?1?TEOS was hydrolysed under basic conditions.Silica nanoparticles of different sizes were obtained by adjusting the ratio of the TEOS,aqueous ammonia,ethanol and water.The surface of silica nanoparticles were changed to positive charge,due to APTES.Then 5 nm gold nanoparticles with negative charge were adsorbed on silica surface.The gold nanoparticles were used as growth sites for the formation of the final gold shell layer.They were characterized with SEM,particle size analyzer,UV-Vis absorption spectroscopy.Different localized surface plasmon resonance peaks of SiO₂@Au nanoparticles were formed with diverse radii ratio of silica and metal shell.?2?Doxorubicin was successfully loaded on SiO₂@Au nanocomposites and can be released due to photothermal effect of SiO₂@Au and pH-sensitive effect of SiO₂@Au@DOX.SiO₂@Au and doxorubicin were reacted at different pH environment.We found that in a neutral environment,the adsorption capacity of DOX was best.More doxorubicin will release in the acidic environment?Cancer cells are survival in this environment.?than in a neutral environment?Normal cells are present in this environment?when SiO₂@Au loaded with doxorubicin were placed in different pH solutions.Doxorubicin will be released under 808 nm laser irradiation,because of the photothermal effect of SiO₂@Au nanocomposites.The composites were characterized with particle size analyzer,UV-Vis absorption spectroscopy,and fluorescence spectroscopy.In addition,we also explored the impact of NH₂-PEG-SH on doxorubicin adsorption capacity.On one side it is feasible to obtain Au-S interaction.On the other side polyethylene glycol with hydroxy can be connected with a hydroxyl group and an amino group of doxorubicin by hydrogen bonds.So,doxorubicin can be loaded on gold shell with NH₂-PEG-SH.NH₂-PEG-SH will increase the loading capacity of doxorubicin.With an increasing number of NH₂-PEG-SH,the loading capacity of doxorubicin will increase and then decrease.When adding a small amount of NH₂-PEG-SH,the hydroxyl groups of NH₂-PEG-SH can be connected with a hydroxyl group and an amino group of doxorubicin by hydrogen bonds,leading to load more doxorubicin.When NH₂-PEG-SH were added in excess,the polymer chain may bend,leading to a less adsorption.