Asian Research Thesis Index

Abstract

We successfully performed green process using the aqueous leaf extracts of medicinal plant Sageretia thea (Osbeck.) to produce multifunctional metal oxide nanoparticles. The biosynthesized Zinc oxide (ZnO), Iron oxide (Fe2O3), Nickel oxide (NiO), Cobalt oxide (Co3O4) and Lead oxide (PbO) nanoparticles were subjected to intensive physical characterization techniques like XRD, FTIR, Raman, EDS, SAED, HR-SEM and HR-TEM. Debye Scherer approximation was used to determine the size of the biogenic nanoparticles. Average sizes of the nanoparticles were calculated as 12.5 nm (ZnO), 29 nm (Fe2O3), 18 nm (NiO), 27 nm (PbO) and 20.03 nm (Co3O4). As synthesized nanoparticles were investigated for their possible biological applications. Antimicrobial, cytotoxic, enzyme inhibition, antioxidant and biocompatibility assays were performed. Antibacterial properties against 6 pathogenic bacterial strains using disc diffusion assay and their MIC’s were calculated. Significant antibacterial potential was revealed for ZnO nanoparticles. Furthermore, the effect of UV-illumination in the enhancement of antibacterial properties was studied. Agar tube dilution method for linear mycelial growth inhibition was used to determine the antifungal potential of biogenic metal oxide nanoparticles. Significant cytotoxicity was revealed against Artemia salina. Dose dependent cytotoxicity is reported for the biosynthesized nanoparticles against Leishamnia tropica (promastigotes and amastigotes) and HepG2 cell lines using MTT cytotoxic assay, while their biocompatibility was assessed against freshly isolated human macrophages and RBC’s. Median lethal concentration (IC50) values were calculated. Significant protein kinase inhibition is indicated by Fe2O3 nanoparticles while insignificant alpha amylase inhibition is reported for biosynthesized nanoparticles. Moderate DPPH radical scavenging activity while insignificant total antioxidant and total reducing potential was indicated. In addition, ZnO nanoparticles were deposited on the 3D porous substrate (nickel foam) to fabricate electrode material for supercapacitor applications. The fabricated NiF/ZnO electrode showed high specific capacitance of ~ 453 F g-1 at a relatively high current density of ~ 2 A g-1. The electrode also showed excellent cycling performance with 86% specific capacitance retention after 1000 cycles. Our results suggest that biosynthesized metal oxide nanoparticles can be used in diverse applications.

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