Photocatalytic and biomedical investigation of green synthesized NiONPs: Toxicities and degradation pathways of Congo red dye

In this study the biomedical and catalytic ability of green synthesized nickel Oxide nanoparticles (NiONPs) was investigated. The extract of medicinal plant Tribulus terrestris were used to synthesized NiONPs. The as-synthesized NiONPs were in nano scale and were characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), High-Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Energy Dispersive X-ray spectroscopy (EDX). The synthesis of NiONPs was ensured with surface Plasmon resonance (SPR) at 425 nm and the strong EDX. The effect of different concentrations of plant extract on the size of NiONPs was evaluated. The HRTEM results showed particle size between 60 - 90 nm. The study showed that lesser the extract concentration, more spherical and small sized particles were obtained without aggregation. The biological applications of NiONPs were evaluated against different fungal species like Asper gillusflavus, Asper gillusfumigatus, Asper gillusniger and standard medicine Terbinafine. A. niger, A. flavus and A. fumigatus exhibited 57, 63 and 52 % inhibition compared with inhibition of the reference medicine which is 98, 100 and 100%. NiONPs have been shown to be more effective against gram-positive bacteria than gram-negative bacteria like E. Coli 9(±0.7) and S. aureus13 (±0.8). Moreover, antioxidant properties of the as-synthesized NiONPs were evaluated with 2, 2 diphenyl-1-picrylhydrazyl) (DPPH). The catalytic ability of green synthesized of NiONP was investigated for the degradation of Congo red dye (CR) as a hazardous environmentally contaminations in water. The biosynthesized NiONPs were found to be active catalytic for the degradation toxic dyes like CR. the catalytic activity of NiONPs can be explained by its small size compared with balk material. Mechanisms for CR degradation have been proposed. The Ecotoxicity of CR and components derived from dye was investigated with Ecological Structure Activity Relationship (ECOSAR) program.