Structural characterizations, DFT, and docking of novel chitosan/PVA/germanium oxide as a potent antimicrobial agent

This study presents the synthesis, characterization, and antibacterial evaluation of a novel Chitosan-PVA-Germanium dioxide (Cs-PVA-GeO₂) composite. The composite was prepared via a casting technique and characterized using X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and density functional theory (DFT). XRD analysis revealed concentration-dependent crystallinity, peaking at 52.7 % for 0.1 wt% GeO₂, with higher concentrations leading to reduced crystallinity due to competing nucleation and structural disruption effects. FTIR confirmed hydrogen bonding between chitosan, PVA, and GeO₂, enhancing the composite's stability. DFT calculations demonstrated that incorporating GeO₂ into the Cs-PVA matrix increased the dipole moment (7.1572 Debye) and reduced the energy gap (5.0325 eV), indicating improved electronic reactivity. The composite exhibited broad-spectrum antibacterial activity against Gram-positive (Staphylococcus aureus, Enterococcus faecalis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) pathogens. Molecular docking studies revealed strong binding affinities of Cs-PVA-GeO₂ with key bacterial enzymes, including DNA gyrase, penicillin-binding proteins (PBPs), and dihydropteroate synthase (DHPS), suggesting a multi-target inhibitory mechanism. These findings point out the advantages of Cs-PVA-GeO₂ as a promising therapeutic agent against multidrug-resistant infections.