Chemical and Biological Synthesis of Cobalt Oxide Nanoparticles: Comparative Study of Antibacterial Activity

Abstract

Green synthesis of NPs using plant extract is a novel method to develop environmentally benign nanomaterials which can be used in numerous biomedical applications. In this study we have synthesized cobalt oxide nanoparticles through biological method using cobalt nitrate hexahydrate as a precursor and indigenous plant extract, Indod (Phytolacca dodecandra) leaf as a reducing and capping agent. Furthermore, the NPs were synthesized chemically by coprecipitation method from cobalt nitrate hexahydrated in the presence of sodium hydroxide as a precipitating agent. The synthesized nanoparticles were characterized using X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The crystal size of the synthesized NPs was calculated using Debye-Scherer equation and was found to be 10.79 nm and 11.9 nm for biologically and chemically synthesized Co3O4 nanoparticles, respectively. The bandgap for biologically and chemically synthesized nanoparticle (NPs) were 3.35 eV and 3.2 eV, respectively. The XRD pattern with sharp peaks describes the crystalline and purity of cobalt oxide nanoparticles. The shape and morphology of Co3O4 nanoparticles were studied by SEM analysis confirms spherical shape and EDX also gave the percent composition of the atom. Thus elemental composition of Co and O in synthesized nanoparticle was 73.22, 94.92% for green and chemically synthesized Co3O4 NPs, respectively. FTIR spectrum discloses the information about the interaction between the functional groups of the phytochemical in the leaf extract and the Co3O4 NPs. Based on the results biologically synthesized Co3O4 nanoparticles calcinated and Uncalcinated have potential antibacterial applications even in small concentration specially for gram negative bacteria compared to chemically synthesized Co3O4 nanoparticles.