Chemistry Department, Universidad Autonoma de Aguascalientes. Av. Universidad 940 C. P., Aguascalientes, Ags., postcode 20100, Mexico.
Dalton Trans. 2011 Feb 7;40(5):1047-54. doi: 10.1039/c0dt00784f. Epub 2010 Dec 15.
Fundamental research has been carried out to define optimal "green" synthesis conditions for the production of titania (TiO(2)) and silver (Ag) nanocomposites (TANCs) ranging from 12.7-22.8 nm in diameter. A bottom-up colloidal approach was employed to accurately control TANC monodispersity and composition. TANCs were found to be effective at inactivating Escherichia coli (E. coli) in water. The presence of Ag in the nanocomposites induced a decrease in TiO(2) band gap energy, which favoured valence to conduction band electron transfer and allowed for electron excitation using visible light. Aggregation of ultra-fine particles was prevented through the use of a long-chain polymer as evidenced by electrophoretic mobility studies. The TANCs catalyzed oxidation of bacterial membranes and cell death or disinfection. Theoretically, the TANC mode of E. coli disinfection is via water photolysis, which results in production of hydroxyl radicals and hydrogen peroxide. These interact with the outer membrane polysaccharides and lipids, leading to lipid peroxidation, membrane weakening and resulted in cell death. Our overarching goals were to optimize the variables involved in TANC "green" synthesis and to characterize its nanostructure. High resolution (HR) transmission and scanning electron microscopic (TEM and SEM) studies demonstrated that TANCs were highly crystalline and mono-dispersive. Elemental composition of Ag and Ti, as measured by X-ray energy dispersive (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed sample purity. Ultraviolet-visible (UV-VIS) spectroscopy showed that the energy band-gap of Ag modified TiO(2) was in the visible range.
已经进行了基础研究，以确定用于生产直径为 12.7-22.8nm 的二氧化钛（TiO(2)）和银（Ag）纳米复合材料（TANC）的最佳“绿色”合成条件。采用自下而上的胶体方法来精确控制 TANC 的单分散性和组成。研究发现，TANC 在水中有效灭活大肠杆菌（E. coli）。纳米复合材料中 Ag 的存在降低了 TiO(2)的能带隙能量，有利于价带到导带的电子转移，并允许使用可见光进行电子激发。通过使用长链聚合物，防止了超细颗粒的聚集，这一点可以通过电泳迁移率研究得到证明。TANC 催化细菌膜的氧化和细胞死亡或消毒。从理论上讲，TANC 对大肠杆菌的消毒模式是通过水的光解，导致产生羟基自由基和过氧化氢。这些与外膜多糖和脂质相互作用，导致脂质过氧化、膜弱化，最终导致细胞死亡。我们的总体目标是优化 TANC“绿色”合成中涉及的变量，并对其纳米结构进行表征。高分辨率（HR）透射和扫描电子显微镜（TEM 和 SEM）研究表明，TANC 具有高结晶度和单分散性。通过 X 射线能量色散（EDS）和 X 射线光电子能谱（XPS）测量的 Ag 和 Ti 的元素组成证实了样品的纯度。紫外可见（UV-VIS）光谱表明，Ag 修饰的 TiO(2)的能带隙在可见光范围内。
