Green Synthesis and Antimicrobial Activity of Copper Nanoparticles (Cu-NPs) by Piper longum Fruit Extract

Many applications of green synthesis in the field of environment and biomedicine aiming at decreasing the use of toxic chemicals through utilizing of plants which are safe. In this study, at 0.1 M concentration of copper sulfate (CuSO4.5H2O), CuNPs were prepared and identified by changing the blue color into green color (ethanolic extract) and from blue color to black color (water extract) and the spectrophotometric detection of ultraviolet and infrared spectra. X-Ray diffraction (XRD) pattern was utilized to confirm the crystal structure of CuNPs. The morphology and size of the CuNPs was measured by a high-resolution transmission electron microscope (HR-TEM). Energy dispersive X-ray (EDX) was used for identification of the elemental composition of CuNPs involving copper and oxygen. Field emission scanning electron microscopy (FESEM) was utilized to confirm the shape of prepared copper nanoparticles. In vitro antibacterial activity was tested using two methods including desk diffusion assay considering zones of inhibition and minimum inhibitory concentration (MIC) against six types of certain bacterial types (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Staphylococcus aureus, Streptococcus pneumoniae and Enterococcus faecalis). The results showed potent inhibitory activity of copper nanoparticles (CuNPs) and water extract (Ext. 2) against all bacterial strains.