Modification of Antibacterial Copolymers on the Surface\nof PVA-Based Microfibers via Thermal Cross-Linking and Their Antibacterial\nProperties

Bacterial infections\non material surfaces are a serious public\nhealth concern worldwide. Although poly(vinyl alcohol) (PVA)-based\nmaterials have great potential as medical devices, they lack antibacterial\nproperties on their surfaces and pose bacterial infection risks during\nimplantation surgery. Copolymers containing antibacterial [2-(methacryloyloxy)ethyl]trimethylammonium\nchloride (METAC) units were used to modify the surfaces of chemically\ncross-linked water-insoluble PVA-based microfibers. The copolymers\nalso had carboxy units that were used to react with the hydroxy group\nof the PVA-based microfibers via a simple thermal treatment at 135\n°C. PVA-based materials containing METAC units exhibit significant\nswelling due to electrostatic repulsions. Because the copolymers were\nmodified on the extreme surface of the microfibers, no difference\nin the diameters between unmodified microfibers (PM-fiber) and copolymers\nwith METAC unit-modified microfibers (PM-METAC-fiber), in both the\ndry and swollen states, was observed. The viable bacterial cell numbers,\nwhich were evaluated by colony counting, decreased by exposure to\nthe poly(METAC-<i>co</i>-methacrylic acid (MAAc)) aqueous\nsolution or PM-METAC-fibers. The value of CFU/mL decreased to 0.1%\n(against B. subtilis) and 3.9% (against E. coli) after contact with the PM-METAC-fibers compared\nto the PM-fibers. The percentage of hemolysis against rabbit red blood\ncells was equivalent to that of the negative control, suggesting that\nPM-METAC-fibers can selectively exhibit antibacterial properties.\nThis modification method can be applied to various PVA-based materials\nif hydroxy groups are present on their surface. This study provides\na facile, cost-effective, and promising strategy to impart antibacterial\nproperties to the surface of PVA-based materials without significantly\naffecting their physicochemical properties.