Green synthesis of copper oxide nanoparticles using Rosmarinus officinalis leaf extract and evaluation of its antimicrobial activity

Due to the development of green technology, researchers are becoming more interested in low-cost, environmental eco-friendly methods for the synthesis of nanoparticles (Nps). In this work, Copper oxide nanoparticles (CuO Nps) were synthesized using a green synthesis technique, with Rosmarinus officinalis leaf extract acting as a capping and reducing agent. The as prepared the samples was characterized using UV-Visible Spectra (UV–VIS), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Scanning Electron Microscopy (SEM). The UV-Visible spectra result showed that strong absorption was observed for characteristic band of green synthesized CuO Nps and exhibit red shift as the weight fraction of CuO Nps increases. The XRD analysis confirmed the formation of CuO Nps, having a typical monoclinic structure with crystalline size ranging from 18 to 26 nm. From FTIR spectral analysis strong and broad peak observed at 3384 cm −1 can be attributed to (O-H) functional groups of the bioactive compounds which act as reducing and capping agents for the synthesis of CuO Nps in the plant extract. The SEM images of green synthesized CuO NPs was appeared to be aggregated form and almost spherical in shape. The antimicrobial activity of CuO Nps was evaluated against S.aureus and B.cereus (gram-positive), E. coli (gram-negative) bacteria strains and C.albicans fungal Pathogen. The result indicated that at weight fraction of 50 %, CuO Nps exhibit highest antimicrobial activity against E. coli, S. aureus , C.albicans and B.cereus with zone of inhibition of 26.0 ± 0.10, 25.0 ± 0.15, 18.1 ± 0.32 and 17.0 ± 0.0 mm respectively. Furthermore, for the E. coli bacterial strain, the minimum inhibitory concentration (MIC) of CuO Nps was found to be 1.56 mg/mL; whereas, for S. aureus and C. albicans was found to be 3.12 mg/mL. Therefore, the present study shows that Rosmarinus officinalis extract can be easily used as a reducing, stabilizing, and capping agent for the effective green synthesis of CuO Nps for antimicrobial agents. Thus, it is believed that synthesis of nanoparticles using low cost and eco-friendly green approach enhanced the antimicrobial activity and other a potentially applications in fields of biomedical.