Green synthesis, characterization and antibacterial activity of copper nanoparticles using L-ascorbic acid as a reducing agent

Abstract

Synthesis of Cu nanoparticles using chemical route offers a competitive alternative approach over the common biological and physical procedures. In this study, simple, economical, convenient and environmentally-friendly chemical reduction technique was used for the production of Cu nanoparticles from CuCl2.2H2O solution using L-ascorbic acid as reducing and capping agent. The effects of concentration of precursor salt and ascorbic acid, reaction time and reaction temperature on the synthesis of Cu nanoparticles were studied. The optical properties of the synthesized Cu nanoparticles were characterized by UV-Vis Spectroscopy while the crystallinity of synthesized Cu nanoparticles was verified with the help of X-ray diffraction analysis. The antimicrobial activity of Cu nanoparticles was determined by Agar disc diffusion method against some selected species of bacteria: two gram positive (Staphylococcus aureus, Streptococcus pyogenes) and two gram negative (Escherichia coli, Pseudomonas aeruginosa). The UV-Vis spectrum of solution of Cu nanoparticles showed a characteristic peak at 423 nm that confirms the preparation of Copper nanoparticles. Moreover, FT-IR spectroscopy was performed to detect the binding effect of ascorbic acid on Cu nanoparticles, and its result indicated that ascorbic acid could prevent oxidation and agglomeration. The findings revealed that Cu nanoparticles formed at a concentration of 3mM Cu- Cl₂.2H₂O solution and 4 mM ascorbic acid exhibited an excellent zone of growth inhibition for both gram-negative and gram-positive bacteria, 16.83+0.42 and 15.50+0.89mm, respectively.

Keywords: - Green synthesis, Copper nanoparticles, Chemical reduction, Optical properties, Antibacterial activity