ABSTRACT
In this study, we aimed to explore the morphologies of porous poly(lactic acid) (PLA) fibers through liquid−liquid phase separation, and investigate the relationship among pore formation, physical properties, and antibacterial activities of the fibers for identifying their potential as drug delivery carriers. Antibacterial activities of gentamicin-, kanamycin-, and amikacin-loaded PLA fibers against E. coli and S. epidermidis were evaluated. The antibacterial activity of drugs against E. coli showed the following profile: gentamicin > amikacin > kanamycin; however, S. epidermidis growth was almost completely inhibited immediately after the administration of all three drugs. The efficiency of gentamicin can be attributed to the electrostatic interactions between the positively and negatively charged antibiotic and bacterial cell membrane, respectively. Furthermore, gentamicin-loaded porous PLA fibers were evaluated as drug delivery systems. The cumulative amount of gentamicin in porous PLA nanofibers was considerably higher than that in other PLA fibers for 168 h, followed by 7:3 PLA > 6:4 PLA > 5:5 PLA > non-porous PLA. The 7:3 PLA fibers were projected to be ideal drug carrier candidates for controlled antibiotic release in delivery systems owing to their interconnected internal structure and the largest surface area (55.61 m2 g−1), pore size (42.19 nm), and pore volume (12.78 cm3 g−1).
ABSTRACT
Plant-derived monoterpenoids have been shown to possess various biological effects, providing a scientific basis for their potential usage as antibacterial agents. Therefore, considering problems surrounding bacteria's antibacterial resistance, the utilization of natural antimicrobial compounds such as monoterpenoids in different industries has gained much attention. The aim of this study was to fabricate and characterize various concentrations of plant-derived monoterpenoids, geraniol (G) and carvacrol (C), loaded into poly(lactic acid) (PLA) nanofibers via emulsion electrospinning. The antibacterial activities of the fabricated nanofibers were evaluated using three types of antibacterial assays (inhibition zone tests, live/dead bacterial cell assays, and antibacterial kinetic growth assays). Among the samples, 10 wt% carvacrol-loaded PLA nanofibers (C10) had the most bactericidal activity, with the widest inhibition zone of 5.26 cm and the highest visible dead bacteria using the inhibition zone test and live/dead bacterial cell assay. In order to quantitatively analyze the antibacterial activities of 5 wt% carvacrol-loaded PLA nanofibers (C5), C10, 5 wt% geraniol-loaded PLA nanofibers (G5), and 10 wt% geraniol-loaded PLA nanofibers (G10) against E. coli and S.epidermidis, growth kinetic curves were analyzed using OD600. For the results, we found that the antibacterial performance was as follows: C10 > C5 > G10 > G5. Overall, carvacrol or geraniol-loaded PLA nanofibers are promising antibacterial materials for improving fiber functionality.
