Plasma-Assisted UV Grafting of Thermo-Responsive Chitosan-co-PNIPAAm Hydrogels on Polypropylene Nonwovens for Antibacterial Biomedical Textiles

Polypropylene (PP) nonwoven is widely used in biomedical textiles because of its lightweight and mechanical durability; however, its inherent hydrophobicity and chemical inertness limit further surface functionalization. In this study, a plasma-assisted UV grafting strategy was developed to fabricate thermo-responsive and antibacterial hydrogel coatings on PP nonwoven. Atmospheric-pressure plasma jet (APPJ) treatment was first employed to activate the PP nonwoven surface, followed by UV-induced graft polymerization of chitosan and <i>N</i>-isopropylacrylamide (NIPAAm), forming a chitosan-<i>co</i>-PNIPAAm hydrogel immobilized on the nonwoven substrate. Surface characterization using water contact angle measurement, Fourier transform infrared spectroscopy, and scanning electron microscopy confirmed effective plasma activation and successful hydrogel grafting. APPJ treatment significantly enhanced surface wettability, whereas subsequent UV grafting formed a continuous hydrogel on the PP nonwoven surface. The modified nonwoven exhibited distinct thermo-responsive swelling behavior in aqueous and simulated physiological environments, associated with the temperature-sensitive characteristics of the PNIPAAm component. In addition, the incorporation of chitosan imparted pronounced antibacterial activity against <i>Escherichia coli</i>, with inhibition zone diameters ranging from 14 to 16.5 mm, indicating high antibacterial sensitivity. Preliminary cytocompatibility evaluation further demonstrated favorable cell viability on the modified surfaces. This study demonstrates a scalable and low-temperature surface engineering approach for integrating stimuli-responsive and antibacterial hydrogel functionality into nonwoven polymer substrates, offering potential for advanced biomedical textile applications.