SYNERGISTIC EFFECT OF CHITOSAN AND NANOCRYSTALLINE CELLULOSE ON THE ANTIMICROBIAL ACTIVITY OF ELECTROSPUN POLYLACTIC ACID (PLA) NANOFIBERS

Abstract

Objective The world is accelerating to find alternative antimicrobial materials due to the rapid development of antibiotic-resistant bacteria. Electrospinning of polymeric nanofibers can provide an attractive platform of developing bioactive surfaces with improved antibacterial functionality. Purpose: The research aimed to determine how the molecular weight of chitosan as well as the incorporation of nanocrystalline cellulose (NCC) affected the morphology and antibacterial activity of polylactic acid (PLA)-based electrospun nanofibers. Methods: Nanofibers were prepared through needle electrospinning method.  The morphological properties of the prepared nanofibers were determined by the use of the scanning electron microscopy (SEM). PLA was blended with two molecular weights of chitosan (7.5kDa and 15 kDa) in 8.5wt% concentration with or without NCC in the concentration of 8.5 wt% as well. The ASTM E2149-13a dynamic contact method was used to assess the anti-bacterial action against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Results: Results showed that the low molecular weight chitosan (7.5 kDa) formed smooth and uniform nanofibers (average diameter =169-180 nm), and chitosan of high molecular weight (15 kDa) formed beads with less homogeneous structures. Formulations with chitosan showed good antibacterial properties with growth inhibition of most strains tested being complete or almost complete in 1 hour. When NCC was added, there was an improvement in the fiber morphology and an increase inits antibacterial activity, especially with the 7.5 kDa chitosan formulation, which is indicating a synergist effect. In comparison, PLA or PLA/NCC fibers in the absence of chitosan exhibited low or ineffective antibacterial activity. Conclusion: The optimized Cs/NCC/PLA nanofibers, especially the one that contained low molecular weight chitosan, had a smoother and more uniform nanofibers and high spectrum antibacterial activity. The combination of chitosan and NCC boosts surface activity and membrane disruption of bacteria, which points to the possibility of using these composite nanofibers in biomedical applications as wound dressings and antimicrobial coating.