Ag-Decorated Hydrogen Molybdenum Bronze Nanotubes as Dual-Action Agents Against Bacillus subtilis: Experimental and Theoretical Insights Into Membrane Damage and Protein Interference

Bacterial biofilms are a persistent challenge in industrial settings such as water treatment and food processing, contributing to antimicrobial resistance, operational inefficiencies, and environmental burden. Here, we report on the synthesis and multiscale evaluation of hydrogen molybdenum bronze nanosheets (HMB-NSHs) and their silver-decorated nanotube derivatives (Ag–decorated HMB-NTs), produced via an arc discharge method. High-resolution structural analyses revealed crystalline, ultrathin HMB sheets and tubular architectures adorned with uniformly distributed Ag nanoparticles (∼3–5 nm). While HMB-NSHs were biologically inert, Ag–decorated HMB-NTs demonstrated potent antibacterial effects against Bacillus subtilis, inhibiting planktonic growth (75.7%), biofilm formation (77.7%), and biofilm eradication (64.3%) at 25 μg/mL. Complementary SEM and fluorescence microscopy visualizations revealed pronounced morphological membrane damage such as wrinkling, roughening, and biofilm reduction signatures absent in control and HMB-treated samples, facilitating metal ion deposition and localized oxidative stress. At the molecular level, multiscale computational modeling, including molecular docking, DFT, QTAIM, RDG, and IGM analyses, provided atomic-resolution insights into dual-site antibacterial action. The Ag and HMB moieties interact favorably with both the cell-wall penicillin-binding protein (PDB ID: 4WO7) and intracellular division regulator FtsZ (PDB ID: 2VAM), forming energetically stable complexes. QTAIM metrics confirmed extensive van der Waals and hydrogen bonding networks with 4WO7, whereas RDG and IGM surfaces visualized dense noncovalent contact regions. Ag–FtsZ interactions, though weaker, suggest possible disruption of cell cycle machinery upon internalization. These findings establish Ag-decorated HMB-NTs as a dual-function nanomaterial: HMB scaffolds promote surface adhesion and stability, whereas Ag enables membrane destabilization and intracellular disruption. Together, these processes highlight membrane damage and protein interference as the primary antibacterial mechanisms, underscoring their potential as a next-generation antibacterial platform, particularly against biofilm-forming and industrially relevant bacteria such as Bacillus subtilis.