Effect of copper salts and reducing agents on characteristics and antimicrobial activity of copper nanoparticles

Copper nanoparticles (CuNPs) were synthesized using different types of copper salts (copper acetate, copper chloride, and copper sulfate) and reducing agents (NaOH and ascorbic acid). The resulting solutions exhibited the maximum absorption peaks between 250-350 nm, which was caused by the change in the surface Plasmon resonance of CuNPs and clearly indicated the formation of CuNPs. The results of FE-SEM exhibited that the CuNPs of various shapes and size, depended upon the type of copper salts and reducing agents used. The FTIR results demonstrated the involvement of bioactive functional groups as reducing and capping agents. XRD spectra confirmed the crystalline nature of CuNPs. Furthermore, all the CuNPs exhibited strong antimicrobial activity against both, Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) food-borne pathogens. (C) 2014 Elsevier B.V. All rights reserved.