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We report the synthesis of Ag/bentonite, ZnO/bentonite and Ag/ZnO/bentonite nanocomposites (NCs) using Hagenia abyssinica plant extract and their antibacterial study. The synthesized NCs were characterized by using many advanced techniques. The X-ray diffraction and high resolution transmission electron microscopy analysis confirmed the formation of composites with different phases. The average crystallite size (D) values of pure Ag nanoparticles (NPs), ZnO NPs, and activated bentonite (Na-AB) were found to be 8.14, 18.1, and 37.6 nm, respectively. The Ag/bentonite NCs, ZnO/bentonite NCs, and Ag/ZnO/bentonite NCs exhibited the D values of 7.4, 9.4, and 9.4 nm, respectively. The Fourier transform infrared spectral analysis revealed the presence of hydroxyl, carbonyl, and other functional groups on the surface of the synthesized NCs. The transmission electron microscopic analysis revealed the formation of Ag and ZnO NPs with hexagonal, rod-shaped, and spherical structures. HRTEM also revealed the presence of (102) plane of ZnO and (220) plane of Ag in Ag/ZnO/bentonite NCs. The antibacterial activities of the composites suspension were evaluated against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 by the disc diffusion and broth dilution methods. The ternary NC and Ag/ZnO/bentonite exhibited better zone of inhibition of 14.3 ± 0.3 and 17.3 ± 0.2 mm at 10 mg·mL−1 toward E. coli and S. aureus bacterial strains. The minimum inhibitory concentration and minimum bactericidal concentration values of Ag/ZnO/bentonite NCs were found to be 156.25 and 312.5 µg·mL−1 for E. coli. The investigation results revealed that the low temperature bio-synthesized Ag/ZnO/bentonite is a promising bactericide over the binary composites.

Green synthesis of metal oxide nanoparticles (NPs) is a viable alternative methodology because of cost-effective and availability of environmentally friendly templates for desired application, which has attracted the attention of researchers in recent years. In the present study, Co3O4 NPs were synthesized in various volume ratios in the presence of Solanum tuberosum leaf extract as a template. The synthesized Co3O4 NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), surface area electron diffraction (SAED), UV-Vis diffuse reflectance spectroscopy (UV-DRS), and Fourier transform infrared (FTIR) spectroscopy. XRD analysis found that the average crystalline sizes for the 1 : 2, 1 : 1, and 2 : 1 volume ratios was 25.83, 21.05, and 27.98 nm, respectively. SEM-EDX and TEM analyses suggest that the green-synthesized Co3O4 NPs are spherical in shape without the presence of impurities. The band gap E g values of the 1 : 2, 1 : 1, and 2 : 1 volume ratios of Co3O4 NPs were found to be 1.83, 1.77, and 2.19 eV, respectively. FTIR analysis confirmed the presence of various bioactive ingredients within the leaf extract of Solanum tuberosum. Co3O4 NPs-modified electrodes showed better sensing capability towards ascorbic acid and citric acid due to enhanced electron transfer kinetics. Among three volume ratios (1 : 2, 1 : 1, and 2 : 1) of Co3O4 nanoelectrodes, 1 : 1 and 2 : 1 were identified as the best performing nanoelectrodes. This is possibly due to the high catalytic behavior and the more homogenized surface structure. Co3O4 (1 : 2) nanodrug showed the enhanced antibacterial activity (16 mm) towards S. aureus which is attributed to the formation of enhanced reactive oxygen species (ROS). [ABSTRACT FROM AUTHOR]

Green synthesis of metal oxide nanoparticles (NPs) is a viable alternative methodology because of cost-effective and availability of environmentally friendly templates for desired application, which has attracted the attention of researchers in recent years. In the present study, Co 3 O 4 NPs were synthesized in various volume ratios in the presence of Solanum tuberosum leaf extract as a template. The synthesized Co 3 O 4 NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), surface area electron diffraction (SAED), UV-Vis diffuse reflectance spectroscopy (UV-DRS), and Fourier transform infrared (FTIR) spectroscopy. XRD analysis found that the average crystalline sizes for the 1 : 2, 1 : 1, and 2 : 1 volume ratios was 25.83, 21.05, and 27.98 nm, respectively. SEM-EDX and TEM analyses suggest that the green-synthesized Co 3 O 4 NPs are spherical in shape without the presence of impurities. The band gap E g values of the 1 : 2, 1 : 1, and 2 : 1 volume ratios of Co 3 O 4 NPs were found to be 1.83, 1.77, and 2.19 eV, respectively. FTIR analysis confirmed the presence of various bioactive ingredients within the leaf extract of Solanum tuberosum . Co 3 O 4 NPs-modified electrodes showed better sensing capability towards ascorbic acid and citric acid due to enhanced electron transfer kinetics. Among three volume ratios (1 : 2, 1 : 1, and 2 : 1) of Co 3 O 4 nanoelectrodes, 1 : 1 and 2 : 1 were identified as the best performing nanoelectrodes. This is possibly due to the high catalytic behavior and the more homogenized surface structure. Co 3 O 4 (1 : 2) nanodrug showed the enhanced antibacterial activity (16 mm) towards S. aureus which is attributed to the formation of enhanced reactive oxygen species (ROS)., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Eneyew Tilahun Bekele et al.)