Department of Environmental Studies, University of Delhi, Delhi, India.
PLoS One. 2013 Apr 23;8(4):e61750. doi: 10.1371/journal.pone.0061750. Print 2013.
We discovered that Yeast Extract Mannitol (YEM) medium possessed immense potential to generate silver nanoparticles from AgNO3 upon autoclaving, which was evident from (i) alteration in color of the medium; (ii) peak at ∼410 nm in UV-Vis spectrum due to surface plasmon resonance specific to silver nanoparticles; and (iii) TEM investigations. TEM coupled with EDX confirmed that distinct nanoparticles were composed of silver. Yeast extract and mannitol were key components of YEM medium responsible for the formation of nanoparticles. PXRD analysis indicated crystalline geometry and Ag/Ag2O phases in nanoparticles generated with YEM medium, yeast extract and mannitol. Our investigations also revealed that both mannitol and yeast extract possessed potential to convert ∼80% of silver ions in 0.5 mM AgNO3 to nanoparticles, on autoclaving for 30 min at 121°C under a pressure of 1.06 kg/cm(2). Addition of filter sterilized AgNO3 under ambient conditions to pre-autoclaved YEM medium and yeast extract brought about color change due to the formation of silver nanoparticles, but required prolonged duration. In general, even after 72 h intensity of color was significantly less than that recorded following autoclaving. Silver nanoparticles formed at room temperature were more heterogeneous compared to that obtained upon autoclaving. In summary, our findings demonstrated that (i) YEM medium and its constituents promote synthesis of silver nanoparticles; and (ii) autoclaving enhances rapid synthesis of silver nanoparticles by YEM medium, yeast extract and mannitol.
我们发现,酵母提取物甘露醇(YEM)培养基在高压灭菌时具有从 AgNO3 生成银纳米粒子的巨大潜力,这可以从以下几点看出:(i)培养基颜色的变化;(ii)由于银纳米粒子特有的表面等离子体共振,在紫外-可见光谱中出现了约 410nm 的峰值;(iii)TEM 研究。TEM 与 EDX 联用证实了明显的纳米粒子是由银组成的。酵母提取物和甘露醇是 YEM 培养基的关键成分,负责纳米粒子的形成。PXRD 分析表明,在 YEM 培养基、酵母提取物和甘露醇生成的纳米粒子中存在结晶几何形状和 Ag/Ag2O 相。我们的研究还表明,甘露醇和酵母提取物都有潜力在 121°C、1.06kg/cm2 的压力下,通过高压灭菌 30 分钟,将 0.5mM AgNO3 中的约 80%的银离子转化为纳米粒子。在环境条件下向预高压灭菌的 YEM 培养基和酵母提取物中添加过滤灭菌的 AgNO3 会因银纳米粒子的形成而导致颜色变化,但需要更长的时间。一般来说,即使在 72 小时后,颜色的强度也明显低于高压灭菌后的记录。在室温下形成的银纳米粒子比高压灭菌后形成的银纳米粒子更不均匀。总之,我们的研究结果表明:(i)YEM 培养基及其成分促进了银纳米粒子的合成;(ii)高压灭菌增强了 YEM 培养基、酵母提取物和甘露醇快速合成银纳米粒子的能力。