Thermo-responsive wound dressings by grafting chitosan and poly(N-isopropylacrylamide) to plasma-induced graft polymerization modified non-woven fabrics

To obtain a chitosan wound dressings with temperature-responsive characteristics, polypropylene (PP) non-woven fabric (NWF) was modified by direct current pulsed oxygen plasma-induced grafting polymerization of acrylic acid (AAc) to improve hydrophilicity and to introduce carboxylic acid groups. Conjugation of chitosan and poly(N-isopropylacrylamide) (PNIPAAm) followed by using water-soluble carbodiimide as a coupling agent to form a novel bigraft PP-g-chitosan-g-PNIPAAm wound dressing. The amount of chitosan and PNIPAAm grafted to PP-g-chitosan-g-PNIPAAm were 83.0 ± 4.6 μg/cm ² and 189.5 ± 8.2 μg/cm ² , respectively. The surface chemical composition and microstructure of the NWF were studied by electron spectroscopy for chemical analysis (ESCA) and scanning electron microscopy (SEM). The linkages between AAc, chitosan, and PNIPAAm were confirmed with the formation of amide bonds. Physical properties of the NWF were characterized and potentials of these NWFs as wound dressings were evaluated using SD rat as the animal model. NWFs contained PNIPAAm were better than those contained only chitosan in wound healing rates and the wound areas covered by PP-g-chitosan-g-PNIPAAm wound dressings healed completely in 17 days.