Interpenetration of metal cations into polyelectrolyte-multilayer-films via layer-by-layer assembly: Selective antibacterial functionality of cationic guar gum/polyacrylic acid- Ag+ nanofilm against resistant E. coli

There is an urging need for the development of effective coating systems to avoid the rapidly growing resistant bacterial strains on medical devices surfaces that causes nosocomial infections. To this end, we studied the interpenetration of metal ions into polysaccharide thin films. Using several types of polyelectrolyte multilayer (PEM) films constructed from polycations; Quaternized cellulose (QC) and Cationic guar gum (CGG), and poly anions; Carboxymethyl cellulose (CMC) and Polyacrylic acid (PAA), we found that doping of Cu2+, Fe2+ and Ag+ metal ions into PEM matrix occurred through the interactions with polyacids groups. The fabricated thin films were characterized before and after metal interpenetration by FTIR, XRD, SEM, EDX, UV-vis, and optical reflectometry (OR). In comparison to QC/CMC and CGG/CMC thin films, CGG/PAA system exhibited maximum metal loading capacity confirmed by EDX and UV-vis, and 75 % reduction in thickness (215-290 nm) confirmed by OR. Ag+ loaded CGG/PAA nanofilm exhibited a robust antibacterial activity as 50-folds than Fe2+ and 150-folds than Cu2+, against resistant E. coli bacteria via down regulation of erm and beta-Lactamase resistance gene expression. Which highlights the efficacy of CGG/PAA-Ag+ as an attractive antibacterial coating material for medical devices.