Investigations into the antibacterial behavior of copper nanoparticles against Escherichia coli
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Zerovalent copper nanoparticles (Cu0) of 12 nm size were synthesized using an inert gas condensation method in which bulk copper metal was evaporated into an inert environment of argon with subsequent cooling for nucleation and growth of nanoparticles. Crystalline structure, morphology and estimation of size of nanoparticles were carried out by X-ray diffraction and transmission electron microscopy. The antibacterial activity of these nanoparticles against the Gram-negative bacterium Escherichia coli was assessed in liquid as well as solid growth media. It was observed from scanning electron microscopic analysis that the interaction of copper nanoparticles with E. coli resulted in the formation of cavities/pits in the bacterial cell wall. The antibacterial property of copper nanoparticles was attributed mainly to adhesion with bacteria because of their opposite electrical charges, resulting in a reduction reaction at the bacterial cell wall. Nanoparticles with a larger surface-to-volume ratio provide more efficient means for antibacterial activity.
KeywordsCopper nanoparticle Antibacterial activity Escherichia coli X-ray diffraction Electron microscopy
The authors express their sincere gratitude and gratefully acknowledge Prof. S. Ismat Shah, Sajid Mehmood, M. Yasin, Moazam Iqbal and Iqtidar Shakoor for their support and technical assistance. A partial financial grant provided by the Higher Education Commission (HEC), Pakistan for this research work is gratefully acknowledged.
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