Biogenic synthesis and characterization of gold nanoparticles by Escherichia coli K12 and its heterogeneous catalysis in degradation of 4-nitrophenol.
Biogenic synthesis and characterization of gold nanoparticles by Escherichia coli K12 and its heterogeneous catalysis in degradation of 4-nitrophenol.
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DOI：
10.1186/1556-276x-8-70
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发表时间：
2013-02-12
影响因子：
--
通讯作者：
Kondo A
中科院分区：
文献类型：
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作者：
Srivastava SK;Yamada R;Ogino C;Kondo A
在不添加生长介质、pH调节和电子供体/稳定剂的情况下，利用大肠杆菌K12细胞在室温下实现了金纳米颗粒(Au NPs)的胞外合成。用紫外-可见(UV-Vis)分光光度法、原子力显微镜、透射电子显微镜和X射线衍射仪对所得纳米粒子进行了分析。得到了高度分散的纳米金片，其尺寸约为50 nm。傅立叶变换红外光谱分析和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法证实了其作用机制是由胞外膜结合蛋白控制的。我们观察到某些膜结合肽负责Au NPs的还原和随后的稳定(由Zeta电位分析证实)。当这些蛋白质失活时，没有观察到纳米颗粒的形成。此外，我们还制备了一种新型的生物催化剂，将金纳米颗粒附着在大肠杆菌K12细胞的膜结合部分上，作为一种高效的多相催化剂，在NaBH4存在下完全还原4-硝基苯酚，并用UV-Vis光谱进行了研究。这是首次报道细菌膜-Au-NP纳米生物复合材料作为一种高效的多相催化剂完全降解水中的硝基芳香族污染物。
Room-temperature extracellular biosynthesis of gold nanoparticles (Au NPs) was achieved using Escherichia coli K12 cells without the addition of growth media, pH adjustments or inclusion of electron donors/stabilizing agents. The resulting nanoparticles were analysed by ultraviolet–visible (UV–vis) spectrophotometry, atomic force microscopy, transmission electron microscopy and X-ray diffraction. Highly dispersed gold nanoplates were achieved in the order of around 50 nm. Further, the underlying mechanism was found to be controlled by certain extracellular membrane-bound proteins, which was confirmed by Fourier transformation-infrared spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis. We observed that certain membrane-bound peptides are responsible for reduction and subsequent stabilization of Au NPs (confirmed by zeta potential analysis). Upon de-activation of these proteins, no nanoparticle formation was observed. Also, we prepared a novel biocatalyst with Au NPs attached to the membrane-bound fraction of E. coli K12 cells serving as an efficient heterogeneous catalyst in complete reduction of 4-nitrophenol in the presence of NaBH4 which was studied with UV–vis spectroscopy. This is the first report on bacterial membrane-Au NP nanobiocomposite serving as an efficient heterogeneous catalyst in complete reduction of nitroaromatic pollutant in water.