A hybrid phosphorus-free nanoparticle with flame retardancy, antibacterial and wound healing promotion for cellulose

The flammability and bacterial susceptibility of cellulose have always posed significant safety hazards in its application. A multifunctional agent (SiCA) combining flame retardancy and antibacterial activity was developed using nano-hybridization in this study. The SiCA was centered around nano-SiO₂, which was modified with a quaternary ammonium salt and a Schiff base. Through chemical grafting, SiCA was successfully immobilized on the cotton fabric surface. Flammability tests revealed that the limiting oxygen index (LOI) value of treated cotton fabric rose significantly from 18 % to 27.5 %. The modified fabric showed a 35.5 % reduction in peak heat release rate (pHRR) and achieved self-extinguishing behavior in UL-94 vertical flame tests. The antibacterial efficacy of modified fabric against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was also validated, with inhibition rates reaching 99.6 %. Furthermore, the biocompatibility of modified fabrics was evaluated using MTS assays and animal wound model. L929 fibroblast cell tests confirmed low toxicity of SiCA. The wound healing rate of 97.3 % was achieved after 14 days in animal model, indicating the function of promoting healing. The excellent flame retardancy, antibacterial, and biocompatibility of modified cotton fabric suggested it was an ideal candidate in military combat training uniforms, infant and toddler clothing, automotive interiors, public transportation, and medical settings.