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A Journal on Biotechnology and Molecular Biology

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Minerva Biotecnologica 2017 March;29(1):14-6

language: English

Biological synthesis of gold nanocolloids using E. coli extract


Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran


BACKGROUND: The synthesis of gold nanoparticles has attracted great attention in the last few decades due to their wide range of potential applications. The present work focuses on biosynthesis of gold nanocolloids employing extract of E. coli.
METHODS: The Muller-Hinton broth (MHB) was prepared, autoclaved, cooled and inoculated with a fresh growth of E. coli. After incubation, the cells were separated from the culture broth by centrifugation and washed two times with deionized water to obtain some wet weight of cells. The harvested cells were then resuspended in deionized water. The cells were then removed by a filter, and the filtrate obtained was extract of cell (EOC). Nanoparticles were formed within 1 hour of gold ion coming in contact with the cell extract filtrate.
RESULTS: The absorption spectra of colloidal gold nanoparticles showed characteristic surface plasmon resonance (SPR) peak centered at a wavelength of 546 nm. In addition, the Au NPs were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The nanocolloids are very stable and no precipitation was observed in 3 months. The results showed the mean size of gold nanoparticles was 63 nm.
CONCLUSIONS: In this work, we explained a cost efficient and green synthetic technique leading to a very stable colloid of gold nanoparticles using extract of E. coli.

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