Motilal Nehru National Institute of Technology Allahabad, Allahabd 211004, India.
J Nanobiotechnology. 2013 Dec 20;11:42. doi: 10.1186/1477-3155-11-42.
In the present contribution, we describe the synthesis of highly dispersed silver nanorods (NRs) of different aspect ratios using a chemical route. The shape and size of the synthesized NRs were characterized by Transmission Electron Microscopy (TEM) and UV-visible spectroscopy. Longitudinal and transverse absorptions bands confirm the rod type structure. The experimentally recorded UV-visible spectra of NRs solutions were fitted by using an expression of the extinction coefficient for rod like nano structures under the dipole approximation. Simulated and experimentally observed UV-visible spectra were compared to determine the aspect ratios (R) of NRs. The average values of R for NR1, NR2 and NR3 solutions are estimated to be 3.0 ± 0.1, 1.8 ± 0.1 and 1.2 ± 0.1, respectively. These values are in good agreement with those obtained by TEM micrographs. The silver NRs of known aspect ratios are used to study antimicrobial activities against B. subtilis (gram positive) and E. coli (gram negative) microbes. We observed that the NRs of intermediate aspect ratio (R = 1.8) have greater antimicrobial effect against both, B. subtilis (gram positive) and E. coli (gram negative). The NRs of aspect ratio, R = 3.0 has better antimicrobial activities against gram positive than on the gram negative.
在本研究中，我们描述了一种使用化学方法合成具有不同纵横比的高度分散银纳米棒（NRs）的方法。通过透射电子显微镜（TEM）和紫外-可见光谱对合成的 NRs 的形状和尺寸进行了表征。纵向和横向吸收带证实了棒状结构。用偶极近似下棒状纳米结构的消光系数表达式对 NRs 溶液的实验记录的紫外-可见光谱进行了拟合。比较了模拟和实验观察到的紫外-可见光谱，以确定 NRs 的纵横比（R）。NR1、NR2 和 NR3 溶液的平均 R 值分别估计为 3.0 ± 0.1、1.8 ± 0.1 和 1.2 ± 0.1。这些值与 TEM 显微照片得到的值吻合较好。用已知纵横比的银 NRs 研究了对枯草芽孢杆菌（革兰氏阳性）和大肠杆菌（革兰氏阴性）微生物的抗菌活性。我们观察到，中间纵横比（R = 1.8）的 NRs 对革兰氏阳性菌（枯草芽孢杆菌）和革兰氏阴性菌（大肠杆菌）均具有更强的抗菌作用。纵横比为 R = 3.0 的 NRs 对革兰氏阳性菌的抗菌活性优于革兰氏阴性菌。
