title: Biogenic synthesis and characterization of gold nanoparticles by Escherichia coli K12 and its heterogeneous catalysis in degradation of 4-nitrophenol.
abstract: 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.
authors: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, 657-8501, Nada, Kobe, Japan. akondo@kobe-u.ac.jp.
authors: Sarvesh Kumar
authors: SK
authors: Srivastava
authors: Ryosuke
authors: R
authors: Yamada
authors: Chiaki
authors: C
authors: Ogino
authors: Akihiko
authors: A
authors: Kondo
references: J Phys Chem B. 2006 Mar 9;110(9):3930-7
references: 16509678
references: J R Soc Interface. 2012 Jul 7;9(72):1705-12
references: 22399790
references: Adv Colloid Interface Sci. 2010 Apr 22;156(1-2):1-13
references: 20181326
references: J Phys Chem B. 2005 Jul 28;109(29):13857-70
references: 16852739
references: J Bacteriol. 2006 May;188(9):3371-81
references: 16621832
references: J Phys Chem B. 2005 Jan 20;109(2):692-704
references: 16866429
references: Chem Rev. 2004 Jan;104(1):293-346
references: 14719978
references: J Phys Chem B. 2005 Jul 7;109(26):12663-76
references: 16852568
references: Appl Environ Microbiol. 1998 Oct;64(10):4068-72
references: 9758845
references: Langmuir. 2011 Sep 6;27(17):10894-900
references: 21786795
references: Langmuir. 2009 Jul 21;25(14):8192-9
references: 19425601
references: Nat Mater. 2003 Mar;2(3):145-50
references: 12612669
references: Nanomedicine. 2010 Apr;6(2):257-62
references: 19616126
references: J Hazard Mater. 2011 May 15;189(1-2):519-25
references: 21420237