Trichogenic Ag2O/CuO Nanoalloys: Biomimetic Synthesis, Physicochemical Characterization, and Plausible Antibacterial Mechanism.

The use of fungi as biological nanofactories is an innovative and promising research field of nanoscience. It offers the potential to yield sustainable and cost-effective nanostructures with fine-tuned features. This study reports the trichogenic synthesis of silver oxide/copper oxide (Ag2O/CuO) nanoalloys, using the culture filtrate of the endophytic fungus <italic>Trichoderma virens</italic><bold><italic>.</italic></bold> The filtrate of <italic>T. virens</italic> mediated the synthesis of the Ag2O/CuO nanoalloys, which was visually verified by the formation of dark bluish-greenish colloidal suspension upon reacting with AgNO3 and CuSO4·5H2O (1:1 v/v). X-ray diffraction revealed the crystalline nature of the trichogenic Ag2O/CuO nanoalloys, showing the characteristic diffraction peaks of cubic Ag2O (Pn-3/201) and tenorite monoclinic CuO (C2/c/15). X-ray photoelectron spectroscopy revealed spectra corresponding to the core levels of Ag 3d, Cu 2p, and O 1 s in the Ag2O/CuO nanoalloys. Fourier-transform infrared spectroscopy showed nitro and ester stretching vibrations in addition to characteristic interatomic metal–metal vibrations near 500 cm−1. Dynamic light scattering revealed that the Ag2O/CuO nanoalloys had an average particle size distribution of 124 nm, while zeta potential measurement was + 23.8 mV. Field-emission scanning electron microscopy (FESEM) revealed a mixture of hemispherical and plate-like Ag2O/CuO particles arranged in crystalline clusters. High-resolution transmission electron microscopy revealed the formation of quasi-spherical, circular, cuboid, and triangular Ag2O NPs along with the sharp-edged nanoplates of CuO particles. Energy-dispersive X-ray analysis showed prominent emission peaks of Ag (12.41%), Cu (17.68%), and O (69.91%). The antibacterial efficacy of the Ag2O/CuO nanoalloys was evaluated against six Gram-negative and three Gram-positive bacterial strains. The Ag2O/CuO nanoalloys exhibited significant antibacterial activity against streptomycin-sensitive <italic>Xanthomonas citri</italic> pv. <italic>citri</italic> (<italic>Xcc</italic>) (17.85 ± 0.735 mm), streptomycin-resistant <italic>Xcc</italic> (17.77 ± 0.720 mm), <italic>Clavibacter michiganensis</italic> subsp<italic>. michiganensis</italic> (17.44 ± 3.492 mm), and <italic>Escherichia coli</italic> (16.23 ± 2.468 mm), whereas the effectiveness of the Ag2O/CuO nanoalloys was moderate against <italic>Salmonella enterica</italic> serovar Typhimurium (12.74 ± 1.302 mm), <italic>Staphylococcus aureus</italic> (12.56 ± 0.667 mm), streptomycin-sensitive <italic>Pectobacterium carotovorum</italic> subsp. <italic>carotovorum</italic> (<italic>Pcc</italic>) (11.77 ± 0.431 mm), streptomycin-resistant <italic>Pcc</italic> (11.63 ± 0.741 mm), and <italic>C</italic>. <italic>michiganensis</italic> subsp. <italic>capsici</italic> (11.62 ± 0.958 mm). The bacterial cells exposed to the Ag2O/CuO nanoalloys exhibited notable morphological changes, such as cell membrane disruption, structural damage, compromised membrane integrity, shrinkage, and swelling. This research lays the groundwork for developing and using trichogenic Ag2O/CuO nanoalloys as highly effective nano-antimicrobial agents for a diverse array of applications.Graphical Abstract: The use of fungi as biological nanofactories is an innovative and promising research field of nanoscience. It offers the potential to yield sustainable and cost-effective nanostructures with fine-tuned features. This study reports the trichogenic synthesis of silver oxide/copper oxide (Ag2O/CuO) nanoalloys, using the culture filtrate of the endophytic fungus <italic>Trichoderma virens</italic><bold><italic>.</italic></bold> The filtrate of <italic>T. virens</italic> mediated the synthesis of the Ag2O/CuO nanoalloys, which was visually verified by the formation of dark bluish-greenish colloidal suspension upon reacting with AgNO3 and CuSO4·5H2O (1:1 v/v). X-ray diffraction revealed the crystalline nature of the trichogenic Ag2O/CuO nanoalloys, showing the characteristic diffraction peaks of cubic Ag2O (Pn-3/201) and tenorite monoclinic CuO (C2/c/15). X-ray photoelectron spectroscopy revealed spectra corresponding to the core levels of Ag 3d, Cu 2p, and O 1 s in the Ag2O/CuO nanoalloys. Fourier-transform infrared spectroscopy showed nitro and ester stretching vibrations in addition to characteristic interatomic metal–metal vibrations near 500 cm−1. Dynamic light scattering revealed that the Ag2O/CuO nanoalloys had an average particle size distribution of 124 nm, while zeta potential measurement was + 23.8 mV. Field-emission scanning electron microscopy (FESEM) revealed a mixture of hemispherical and plate-like Ag2O/CuO particles arranged in crystalline clusters. High-resolution transmission electron microscopy revealed the formation of quasi-spherical, circular, cuboid, and triangular Ag2O NPs along with the sharp-edged nanoplates of CuO particles. Energy-dispersive X-ray analysis showed prominent emission peaks of Ag (12.41%), Cu (17.68%), and O (69.91%). The antibacterial efficacy of the Ag2O/CuO nanoalloys was evaluated against six Gram-negative and three Gram-positive bacterial strains. The Ag2O/CuO nanoalloys exhibited significant antibacterial activity against streptomycin-sensitive <italic>Xanthomonas citri</italic> pv. <italic>citri</italic> (<italic>Xcc</italic>) (17.85 ± 0.735 mm), streptomycin-resistant <italic>Xcc</italic> (17.77 ± 0.720 mm), <italic>Clavibacter michiganensis</italic> subsp<italic>. michiganensis</italic> (17.44 ± 3.492 mm), and <italic>Escherichia coli</italic> (16.23 ± 2.468 mm), whereas the effectiveness of the Ag2O/CuO nanoalloys was moderate against <italic>Salmonella enterica</italic> serovar Typhimurium (12.74 ± 1.302 mm), <italic>Staphylococcus aureus</italic> (12.56 ± 0.667 mm), streptomycin-sensitive <italic>Pectobacterium carotovorum</italic> subsp. <italic>carotovorum</italic> (<italic>Pcc</italic>) (11.77 ± 0.431 mm), streptomycin-resistant <italic>Pcc</italic> (11.63 ± 0.741 mm), and <italic>C</italic>. <italic>michiganensis</italic> subsp. <italic>capsici</italic> (11.62 ± 0.958 mm). The bacterial cells exposed to the Ag2O/CuO nanoalloys exhibited notable morphological changes, such as cell membrane disruption, structural damage, compromised membrane integrity, shrinkage, and swelling. This research lays the groundwork for developing and using trichogenic Ag2O/CuO nanoalloys as highly effective nano-antimicrobial agents for a diverse array of applications. [ABSTRACT FROM AUTHOR]