Department of Biotechnology, Manipal Institute of Technology, Manipal University, Manipal 576104, Karnataka, India.
Colloids Surf B Biointerfaces. 2011 Sep 1;86(2):378-83. doi: 10.1016/j.colsurfb.2011.04.024. Epub 2011 Apr 21.
Large number of papers has been published recently on the eleventh group metallic elements such as Ag, Au and Cu. Our study was focused on biosynthesis of silver nanoparticles, their morphology, reactivity and stability. We were interested to check these properties in two different samples, S1 and S2, respectively. The biosynthesis of silver nanoparticles was achieved by reacting the samples with 1 mM concentration of silver nitrate, one involves bacteria (S1) and the other involves the plant extract (S2). Spectrophotometric analysis revealed that the particles exhibited two peaks, one at 440 nm (for S1) and the other at 390 nm (for S2). It is well known that longer wavelength corresponds to increase in particle size. Since, S1 has got a longer wavelength; it is not known, whether it forms isolated particles or agglomerates? Morphological characterization has been done by adopting the procedures of Negative staining and Wedge smear preparation methods. This hybrid method may be of interest to study agglomerated particles. Microscopic examination of the smear S1 shows predominantly triangular or hexagonal shaped agglomerated particles which were not observed in S2. Hence further characterization was done using SEM, EDAX and XRD. The S2 particles were in the range of 45-70 nm and were stable for even four months. This study indicated that particle size can be controlled from micrometer to nanometer size by varying biological reductants.
最近有大量关于第十一族金属元素（如银、金和铜）的论文发表。我们的研究集中在银纳米粒子的生物合成、形貌、反应性和稳定性上。我们有兴趣分别在两个不同的样品 S1 和 S2 中检查这些性质。银纳米粒子的生物合成是通过将样品与 1mM 浓度的硝酸银反应来实现的，其中一个涉及细菌（S1），另一个涉及植物提取物（S2）。分光光度分析表明，这些粒子表现出两个峰，一个在 440nm（对于 S1），另一个在 390nm（对于 S2）。众所周知，较长的波长对应于粒径的增加。由于 S1 具有较长的波长，因此尚不清楚它是形成孤立的粒子还是聚集体？采用负染色和楔形涂片制备方法进行了形貌表征。这种混合方法可能对研究团聚粒子感兴趣。S1 的涂片的显微镜检查显示出主要是三角形或六边形的团聚粒子，而在 S2 中没有观察到。因此，使用 SEM、EDAX 和 XRD 进一步进行了表征。S2 粒子的尺寸在 45-70nm 之间，即使四个月后也保持稳定。这项研究表明，通过改变生物还原剂，可以将粒径从微米控制到纳米尺寸。
