Department of Applied Chemistry, Kinki University, 3-4-1 Kowakae, Higashi-osaka, Osaka 577-8502, Japan.
J Colloid Interface Sci. 2011 Oct 15;362(2):325-9. doi: 10.1016/j.jcis.2011.07.010. Epub 2011 Jul 18.
Gold nanoparticles were fabricated by reduction of highly concentrated Au(III) ions (200 mM) with casein proteins from milk. The gold nanoparticles were converted to nanoparticle-powders after washing and subsequent vacuum drying without aggregation. The nanoparticle-powders completely re-dispersed in aqueous solution, and stable colloidal gold nanoparticles were obtained. UV-vis extinction spectra and dynamic light scattering (DLS) measurements revealed that large assemblies (size, ca. 3 μm) and subaggregates (size, <0.5 μm) composed of gold nanoparticle-casein protein chain-Au(III) ion were dynamically formed and disintegrated over the course of the growth of the gold nanoparticles. Fourier transform infrared (FT-IR) spectra indicated conformational changes of casein proteins induced by the interaction of casein protein-Au(III) ion and -gold nanoparticle. Finally, rapid, one-pot, and highly concentrated synthetic procedures of gold and silver nanoparticle powders protected by casein (mean diameters below 10 nm) were successfully developed using 3-amino-1-propanol aqueous solutions as reaction media. Dense colloidal gold (40 g L(-1)) and silver (22 g L(-1)) nanoparticle aqueous solutions were obtained by re-dispersing the metal nanoparticle powders.
采用牛血清白蛋白（casein）从高浓度的金（III）离子（200mM）溶液中制备金纳米粒子。洗涤并真空干燥后得到金纳米粒子粉末，在此过程中金纳米粒子没有发生聚集。纳米粒子粉末完全重新分散在水溶液中，得到稳定的胶体金纳米粒子。紫外可见吸收光谱和动态光散射（DLS）测量表明，在金纳米粒子生长过程中，金纳米粒子-牛血清白蛋白-金（III）离子组装体（尺寸约 3μm）和亚组装体（尺寸<0.5μm）不断形成和瓦解。傅里叶变换红外（FT-IR）光谱表明，牛血清白蛋白与金（III）离子和金纳米粒子相互作用诱导了牛血清白蛋白的构象变化。最后，采用 3-氨基-1-丙醇水溶液作为反应介质，成功开发了快速、一锅法、高浓度的金和银纳米粒子保护的牛血清白蛋白纳米粒子粉末的合成方法（平均粒径低于 10nm）。通过重新分散金属纳米粒子粉末，得到了高浓度的胶体金（40gL-1）和银（22gL-1）纳米粒子水溶液。
