Electrochemical Studies and Antimicrobial Properties of Synthesized Green Mediated Metal Oxide Nanoparticles

Abstract

Nanoparticles synthesized through alternate biological methods are known to be more biocompatible with no toxic effects. The biological method of synthesis relies on the ability of organic compounds to reduce metal ions and stabilize them into nanoparticles. In this study, a green approach was reported for the fabrication of zinc and iron oxide nanoparticles using extracts from leaf and flower of pomegranate (Punica granatum) plant. The obtained extracts were evaluated for phytochemicals that are expected to function as capping, reducing and stabilizing agents during synthesis. Primary phytochemical analysis of the extracts indicated the presence of bioactive components including phenol, tannins, flavonoids and alkaloids. The biologically stable nanoparticles obtained were characterized spectroscopically and electrochemically. X-ray diffraction analysis (XRD) of the particles revealed the elemental components and nature of the synthesized particles. The XRD pattern spectrum obtained indicated a crystalline structure for the zinc oxide nanoparticles and an amorphous nature for the iron oxide nanoparticles. Morphology of the nanoparticles as shown by Scanning electron microscopy (SEM) was unevenly shaped for the ZnO-NPs and evenly spherical for the Fe₃O₄-NPs. The functional groups involved in stabilization, reduction and capping were confirmed using FTIR. Energy Dispersive X-Ray (EDX) analysis of the synthesized nanoparticles revealed compositions the oxides with peaks of zinc and oxygen components for the ZnO-NPs and iron and oxygen for the Fe₃O₄-NPs. Confirmation of the nanoparticles by UV-Vis analysis showed absorption bands of 284 nm and 357 nm for pomegranate leaf and flower extract mediated ZnO-NPs respectively while Fe₃O₄-NPs absorbance was at 308 nm and 310 nm respectively for leaf and flower mediated nanoparticles. The nanoparticles were further characterized electrochemically using a cyclic voltammetry tool to evaluate their electrochemical properties. The Voltammogram obtained from the electrochemical characterization of the synthesized zinc oxide nanoparticles and iron oxide nanoparticles showed good electrochemical behaviour of the nanoparticles, which indicates that they can be used as biocatalysts. Evaluation of the antimicrobial efficacy of the fabricated nanoparticles showed that ZnO-NPs were effective against all selected pathogenic strains; Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Salmonella diarizonae, Salmonella typhi, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Moraxella catarrhalis, Aeromonas hydrophilia, and Listeria monocytogenes used in the analysis. Iron oxide nanoparticles also showed activity against the pathogenic strains with the exception of Klebsiella pneumoniae in the case of iron oxide synthesized via pomegranate flower (Fe₃O₄-NPs -PF). The effectiveness of the nanoparticles could be linked to their sizes and shapes as obtained using transmission electron microscopy. Our reports also showed that an increase in concentration of the nanoparticles from 50 μg/ml to 5000 μg/ml led to an increase in the antibacterial effect exerted by the nanoparticles (4.33 mm to 23mm), and this suggests that both ZnO-NPs and Fe₃O₄-NPs can effectively be employed as an alternative to conventional antibiotics. However, further research is required to understand the mechanism of action and the possibility of any dangerous effects of their use.