Dialdehyde cellulose nanofibrils/polyquaternium stabilized ultra-fine silver nanoparticles for synergistic antibacterial therapy

Dialdehyde cellulose nanofibrils (DACNF) and Polyquaternium-10 (PQ: chloro-2-hydroxy-3-(trimethylamino) propyl polyethylene glycol cellulose) have become increasingly favored as antibacterial substances due to their advantageous characteristics. DACNF exhibits exceptional mechanical properties and biocompatibility, whereas PQ demonstrates a positive charge that enhances its antibacterial activity. Combined in a DACNF/PQ mixture, they provide an excellent template material for preparing and stabilizing ultra-fine (similar to 10.3 nm) silver nanoparticles (AgNPs) at room temperature. Here, the dialdehyde group of DACNF functions as a reducing agent, while the quaternary ammonium of PQ and carboxylate groups of DACNF synergistically helped in-situ generation of AgNPs uniformly. The synthesized nanocomposites, namely PQ@AgNPs, AgNPs@DACNF, and AgNPs@DACNF/PQ, were subjected to comprehensive characterization using various advanced analytical techniques. The films containing AgNPs@DACNF and AgNPs@DACNF/PQ, fabricated via vacuum filtration, exhibited excellent mechanical properties of 9.78 +/- 0.21 MPa, and demonstrated superior antibacterial activity against both Escherichia coli and Staphylococcus aureus. Additionally, the silver ion leaching from the prepared composite films was well controlled. The fabricated nanocomposites also effectively inhibited bacterial biofilm formation. It was also found to be highly biocompatible and non-toxic to human skin fibroblast cells. Furthermore, the nanocomposites exhibited enhanced migration of human dermal fibroblasts, suggesting their potential in facilitating wound healing processes.