Phytosynthesis of nearly monodisperse CuO nanospheres using Phyllanthus reticulatus/Conyza bonariensis and its antioxidant/antibacterial assays

Abstract In the present article we have developed an eco-friendly, phytosynthetic, cost-effective and straightforward method for the synthesis of nearly monodisperse CuO nanospheres (NSP) using leaf extracts of medicinal plants Phyllanthus reticulatus (PR) and Conyza bonariensis (CB) as novel green reducing agents. Copper nitrate (Cu (NO 3 ) 2 ) was used as a precursor. The stoichiometric ratio of both leaf extracts (PR/CB) and Cu(NO 3 ) 2 was standardized for the synthesis of NSP. During formation of CuO NSP, a color of solution gradually changed from light greenish-blue to black with a number of intermediate stages and it correlated to the reduction reaction catalyzed by phytochemicals. As-synthesized materials were characterized in detail at the structural, electronic level and morphological authentication by XRD, FT-IR, EDS, UV-DRS, Raman, XPS, SEM, TEM, BET and AFM. SEM studies of phytosynthesized materials revealed nearly monodisperse nanospheres, while TEM rendered average particles size 4–14 nm. Also, AFM profiles suggested a homogenized nature of the nanospheres. Then, the antioxidant property was obtained by α, α-diphenyl-β-picrylhydrazyl (DPPH). Ethanolic, methanolic extracts were used for the antioxidant activity, while ascorbic acid was used as a standard medium. Each plant extract exhibited noteworthy antioxidant activity. Moreover, the antibacterial activity of CuO NSP (PR/CB) was tested against human pathogenic bacteria viz. gram-positive Staphylococcus aureus , Klebsiella pneumoniae , and gram-negative Escherichia coli . Result rendered effective antibacterial activity against Escherichia coli .