Green and efficient radiation-based preparation of crosslinked poly(vinyl pyrrolidone)-iodine (PVP-I)-introduced polypropylene (PP) sheets for antibacterial wound dressing application

In this study, we developed an efficient method to prepare a crosslinked poly(vinyl pyrrolidone)/poly(ethylene glycol) diacrylate) (PVP/PEGDA) copolymer-grafted non-woven polypropylene (PP) sheet for which water can be used as a green solvent while providing a large amount of grafting functional groups on the PP matrix without diminishing mechanical properties. It was demonstrated that subsequent iodine complexation of the PP-g-PVP/PEGDA produces a strong antibacterial activity desirable for wound dressings. Efficient functionalization of hydrophobic non-woven PP sheet was achieved using electron beam (EB)-induced graft polymerization of vinyl pyrrolidone (VP) with the addition of hydrophilic crosslinker (PEGDA), resulting in the PP-g-PVP/PEGDA. In this preparation method, the grafting degree was remarkably increased up to 3-fold, even in the water solvent, and was found to be controlled by the concentration of VP and PEGDA. To impart antibacterial activity, the PP-g-PVP/PEGDA subsequently underwent iodine complexation, yielding PP-g-PVP/PEGDA-I. Structural analysis and water absorptivity studies confirmed that excellent water-absorbing PVP/PEGDA-I complexes were successfully introduced in the non-woven PP sheet without significant change in the porous structure of the PP sheet. Moreover, the PP-g-PVP/PEGDA-I exhibited strong antibacterial activities against Gram-negative E. coli, Gram-positive S. aureus, and MRSA bacterial species in a time-killing assay, and the activities showed high dependence on the grafting degree. This finding demonstrates that the PP-g-PVP/PEGDA-I can effectively and immediately inactivate external bacteria upon invasion. This green and efficient strategy is thus promising to produce PVP-I complex-based wound dressings with rapid antibacterial activity.