Structural characterization, spectral investigation and antimicrobial studies Of ZnWO4 and Zn0.9Cu0.1WO4 nanoparticles synthesized by microwave and sucrose mediated solgel method

Abstract

Zinc-Copper tungstates of varying composition were synthesized by sucrose mediated solgel (SSG) method and by microwave assisted metathetic approach (MWMA). The structural characterizations of nanoparticles, NPs were investigated by X-ray diffraction technique (XRD). The average crystallite size of ZnWO4-SSG (ZW-S), Zn0.9Cu0.1WO4-SSG (ZCW-S), Zn0.9Cu0.1WO4−MWMA (ZCW- M) NPs were found to be 20.19 nm, 19.18 nm and 21.12 nm respectively. Elemental mapping at the micro structural level were done using scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS). The characteristic vibrational modes of O-W-O and Zn-O-W were analysed by FTIR and Raman spectral studies. The optical performance of synthesised NPs exhibits smart optical properties with band gap of 2.88, 2.53and 2.59 eV for ZW-S, ZCW-S and ZCW-M respectively using UV-Visible Diffuse Reflectance Spectroscopy, DRS. The antibacterial and antifungal activities of ZW-S, ZCW-S and ZCW-M NPs of varying concentrations25, 50, 75 and 100 µg/ml were tested against one Gram-positive––Staphylococcus aureus, two Gram-negative––Escherichia coli, Pseudomonas aeruginosa human pathogenic bacteria; and three fungal strains––Aspergillus niger, Aspergillus fumigatus, Candida albicans. Further, the ZCW-S NPs adopted “Apoptosis” mechanism for inhibiting fungal cells and Cu2+in ZCW-S undergoes a mechanism of “Homeostasis”. In the present investigation it was established that ZCW-S NPs was effective against Staphylococcus aureus than the standard azithromycin drug.