Inhibition of foodborne bacterial pathogens using novel mycosynthesized cobalt nano ferrites and CoFe2O4 nanoparticles anchored on functionalized multi-walled carbon nanotube bionanocomposites

Abstract

Cobalt nanoferrites and their nanocomposites have attracted significant attention because of their numerous applications. This study reports a novel mycosynthesis of cobalt ferrite nanoparticles (CoFe2O4 NPs) and cobalt ferrite/functionalized multi-walled carbon nanotube (CoFe2O4/fMWCNT) bionanocomposites using the mycelial cell-free filtrate (MCFF) of Aspergillus sojae (KACC 45023). The reaction of A. sojae MCFF with ferric nitrate nonahydrate and cobalt chloride hexahydrate resulted in changing the colorless solution of the MCFF to reddish-brown color and formation of a reddish-brown precipitate, indicating the mycosynthesis of CoFe2O4 NPs. The mycosynthesized CoFe2O4 NPs were biologically anchored onto fMWCNTs using A. sojae MCFF, yielding CoFe2O4/fMWCNT bionanocomposites. Physicochemical and morphological properties of the mycosynthesized CoFe2O4 NPs and CoFe2O4/fMWCNT bionanocomposites were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, zeta potential analysis, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy. The mycosynthesized CoFe2O4 NPs and CoFe2O4/fMWCNT bionanocomposites showed significant antibacterial potential against three foodborne pathogenic bacteria, Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus using an agar-well diffusion assay. The morphological structures of the bacterial cells examined by FESEM revealed changes in the intact bacterial cell structures into misshapen and twisted bacterial cells, as well as deposition of the mycosynthesized CoFe2O4 NPs and CoFe2O4/fMWCNT bionanocomposites on the bacterial cells. The present study reveals the high potential of fungi as valuable bionanofactories for the mycosynthesis of ferrite-based NPs and their bionanocomposites as eco-friendly biosynthesis routes.