Customized atmospheric pressure plasma polymerization process with an acrylic acid-based hybrid precursor on polylactic acid nonwoven for antibacterial scaffolds

There is considerable interest in applying polylactic acid (PLA) nonwoven as a scaffold in biomaterials due to its porous structure, biodegradability, favourable mechanical properties and renewable nature. However, the chemically inert and hydrophobic surface of PLA limits its biocompatibility and poses challenges to improving its antibacterial ability through modification for inhibiting postoperative infection. In addition, PLA nonwoven is sensitive to most chemical methods for both functionalization and sterilisation. To tackle these issues without impairing PLA nonwovens, a tailored atmospheric pressure plasma (APP) system along with a hybrid precursor of acrylic acid and silver nitrate was designed and employed for surface functionalization. In this system, electrons and reactive species created during the APP process were utilised for reducing silver nanoparticles from the hybrid precursor. By performing APP polymerization and reduction simultaneously, we prepared a silver nanoparticle-embedded and carboxyl-rich polymerized film was prepared and deposited on the PLA nonwoven surface. This study presents a comprehensive analysis of the wettability, hydrophilicity stability, surface elemental composition, biocompatibility and antibacterial efficacy of the PLA nonwoven surface functionalized by the proposed APP method. Compared to conventional methods, this process is capable of immobilising a higher percentage of carboxyl functional groups with improved efficiency in enhancing antibacterial properties.