Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi, India.
Colloids Surf B Biointerfaces. 2010 Mar 1;76(1):164-9. doi: 10.1016/j.colsurfb.2009.10.029. Epub 2009 Nov 6.
This work describes an easy chemical method for the preparation of orange-red color silver sol by the cysteine reduction of silver (I) in the presence of cetyltrimethylammonium bromide (CTAB). The obtained sol was found to have very small particles in the order of quantum dots for the first time. Transmission electron microscope (TEM) images show that the silver sol consists of aggregated as well as cross-linking arrangement of spherical silver quantum dots (size in the range ca. <or=16nm). In addition, we observed the changes in the morphologies of the Ag-nanoparticles from quantum dots to nanorod of diameter 60nm and pearl-necklace shaped which occurred due to the cross-linking aggregation of silver quantum dots. For a certain reaction time, i.e., 100min, the absorbance of reaction mixture first increased until it reached a maximum, then decreased with [cysteine]. The rate of Ag-nanoparticles formation decreases with the increase in [cysteine] whereas [CTAB] and [Ag(+)] have no effect on the reaction rate. Interestingly, at higher [cysteine] (>or=20.0x10(-4)mol dm(-3)), white precipitate was formed instead of transparent silver sol. Cysteine acts as a reducing, cross-linking, stabilizing and buffering agent during the growth of different shape and size of silver nanoparticles.
这项工作描述了一种通过半胱氨酸还原银（I）在十六烷基三甲基溴化铵（CTAB）存在下制备橙红色银溶胶的简单化学方法。首次发现所得溶胶具有量子点大小的非常小的颗粒。透射电子显微镜（TEM）图像显示，银溶胶由聚集以及交联排列的球形银量子点组成（尺寸约为 <or=16nm）。此外，我们观察到由于银量子点的交联聚集，Ag-纳米粒子的形态从量子点变化为直径为 60nm 的纳米棒和珍珠项链形状。对于一定的反应时间，即 100min，反应混合物的吸光度首先增加，直到达到最大值，然后随着 [半胱氨酸] 的增加而降低。Ag-纳米颗粒形成的速率随着 [半胱氨酸] 的增加而降低，而 [CTAB] 和 [Ag(+)] 对反应速率没有影响。有趣的是，在较高的 [半胱氨酸]（>or=20.0x10(-4)mol dm(-3)）下，形成了白色沉淀而不是透明的银溶胶。半胱氨酸在不同形状和尺寸的银纳米颗粒的生长过程中充当还原剂、交联剂、稳定剂和缓冲剂。
