Antibacterial activity of the new copper nanoparticles and Cu NPs/chitosan solution

Nanoproducts find wide-ranging applications, from medicine and pharmaceutics to electronic industry, optics and environmental protection. Metallic nanoparticles (NPs) with antibacterial properties represent a promising alternative approach to antibiotics. Copper nanoparticles display high biological activity, comparatively low cost, ecological safety and could be considered as promising multifunctional antibacterial agents. Preparation of new antimicrobial release systems based on Cu NP and biological polymers will contribute to create effective antimicrobial agent. The purpose of current research is to examine the antibacterial activity of the Cu NPs and Cu NPs/chitosan solution against methicillin-resistant Staphyloccus aureus MRSA and multidrug resistant E. coli clinical isolates. Cu NPs were synthesized via chemical reduction method using ginger (Zingiber officinale) and L-ascorbic acid. Chitosan (200 and 500 kDa)-NPs solution with different concentrations was prepared before experiment. X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), SEM energy dispersive microanalysis (EDS), infrared (FTIR) and UV-Vis spectroscopies were used for NPs characterization. The antimicrobial activity of the Cu NPS and CuNP/chitosan solution was tested against 10 MRSA and 5 multidrug-resistant E. coli clinical strains. Physicochemical characterization of Cu NPs showed that they consist of copper core and copper (IV) oxide shell, and the surface of the NPs contained organic compounds originated from ginger and ascorbic acid that served as capping and reducing agents. Cu NPs were approximately 15-20 nm in size and exhibited an ability to self-organization into roundish structures 770±90 nm in size. Pure copper NPs, synthesized via chemical reduction method, affected multiresistant clinical strains of S. aureus and E. coli in concentration of 0.35 μg/ml and 0.7 μg/ml. NPs in 200 kDa chitosan solution effective against MRSA strains in concentration 0.17 μg/ml. But Cu NPs in 500 kDa chitosan solution have no antibacterial effect.