Hydrothermally Synthesized Ag Decorated ZnO/MWCNT Nanocomposites: Characterization and Enhanced Antibacterial Efficacy

Abstract

Given the urgent global health threat posed by antimicrobial resistance and the limitations of conventional antibiotics, this research explores the simultaneous effects of silver (Ag) decoration and multi-walled carbon nanotubes (MWCNTs) combined with zinc oxide (ZnO) nanostructures as a promising alternative with enhanced antibacterial efficiency. The Ag-decorated nanocomposites were hydrothermally synthesized with varying MWCNT concentrations (0, 0.5, 1, 2.5, and 5 wt%). Versatile techniques were applied to characterize the morphological, elemental composition, optical, and structural characteristics of the prepared samples. A significant band gap reduction from 3.17 eV for pristine ZnO to 2.97 eV for 5% MWCNT sample and enhanced visible light absorption were observed, indicating improved optical properties. Antibacterial tests revealed that Ag-decorated ZnO (ZA) and 1% MWCNT (ZAC 1) samples showed the highest activity against Escherichia coli (zone of inhibition diameter (ZOI) = 10.0 mm at 25 mg/mL, MIC = 1.56 mg/mL, MBC = 3.12 mg/mL) and Staphylococcus aureus (ZOI = 10.0 mm at 25 mg/mL, MIC = 1.56 mg/mL, MBC = 3.12 mg/mL), respectively, using disk diffusion and broth microdilution methods. Higher CNT concentrations caused nanotube aggregation, thereby decreasing antibacterial efficacy. The results of this study emphasize the potential use of synthesized nanocomposites in biomedical disinfection technologies and other related applications.