Fabrication and properties of electrospun composite nanofibers based on antibacterial alginate derivatives

Sodium alginate (SA) is difficult to directly electrospin into nanofibers due to its high molecular rigidity and poor chain entanglement capability. In this study, 6-aminopenicillanic acid (6-APA) was employed as a hydrophobic modifier to prepare oxidized sodium alginate-grafted penicillanic acid derivative (OSA-g-APA) with a substitution degree of 29.7% through redox-amination reaction. Subsequently, OSA-g-APA/PVA electrospun composite nanofibers were successfully fabricated using polyvinyl alcohol (PVA) as a spinning aid. Experimental results reveal that chemical modification reduce the critical aggregation concentration (CAC) of OSA-g-APA to 0.440 g/L, enabling self-assembly into stable micelles with an average hydrodynamic diameter of 343.75 nm (PDI=0.39) and Zeta potential of approximately −45.6 mV. Moreover, hydrophobic group grafting not only disrupts intra- and intermolecular hydrogen bonds in SA to enhance molecular chain flexibility, but also strengthens chain entanglement with PVA through hydrophobic association. Although pure OSA-g-APA aqueous solution still fails to produce bead-free fibers, it significantly increases OSA-g-APA content in well-structured OSA-g-APA/PVA composite nanofibers. Furthermore, these composite fibers demonstrate high encapsulation efficiency (EE) and sustained-release characteristics for hydrophobic triclosan (TCA), along with low cytotoxicity and remarkable antibacterial activity. Given the regular fibrous morphology, excellent hydrophobic drug loading/release performance, superior cytocompatibility, and antibacterial properties, OSA-g-APA/PVA electrospun composite nanofibers show promising potential as antibacterial drug delivery systems for functional wound dressing applications.