Ag-ZnO nanoparticles synergy in structurally adjustable cellulose filaments enables high antibacterial efficiency with low cytotoxicity

Direct fabrication of antimicrobial cellulose filaments by wet spinning remains challenging due to complex nanoparticle synthesis and dispersion issues. To address this, we developed a one-pot in situ synthesis strategy within a cellulose-dissolving alkaline system. In this approach, the hydroxyl and terminal aldehyde groups of cellulose chains facilitate the in-situ formation of antibacterial particles (Ag NPs, ZnO). By modulating the particles composition and coagulation bath, we have produced three structurally distinct antibacterial regenerated cellulose filaments. These are designated as regenerated cellulose filaments contain Ag NPs (ACF), regenerated cellulose filaments contain ZnO particle (ZCF) and regenerated cellulose filaments contain ZnO particle and Ag NPs (AZCF). ACF exhibited a smooth surface with limited silver nanoparticle visibility, ZCF displayed surface roughness due to ZnO particle aggregation, and AZCF maintained surface smoothness with dense, uniform nanoparticle distribution. This phenomenon is attributed to the interactions of Ag NPs and ZnO particles. Based on this interaction, the regenerated cellulose developed in this study exhibit both antimicrobial activity (> 95 % bactericidal rates against both E. coli and S. aureus ) and low cytotoxicity. Mechanistic investigations indicate that its antibacterial effects originated from the synergistic action of reactive oxygen species (ROS) production and regulated metal ion release.