Electrospun shikonin-loaded PCL/PTMC composite fiber mats with potential biomedical applications

Novel electrospun poly(epsilon-caprolactone) (PCL)/poly(trimethylene carbonate) (PTMC) ultrafine composite fiber mats were prepared and used as drug-carrying materials to encapsulate the herbal medicine shikonin isolated from the plant Lithospermum erythrorhizon Sieb. et Zucc. The PCL/PTMC blended solutions in various ratios (9:1, 7:3, and 5:5, w/w) containing 1 and 5 wt.% shikonin were studied for electrospinning into nanoscale fiber mats. With good drug stability and high drug-loading efficacy, incorporation of shikonin in the polymer media did not appear to influence the morphology of the resulting fibers, as both the drug-free and the shikonin-loaded composite fibers remained unaltered, microscopically. The average diameter of the composite fibers decreased, and the morphology of the fibers became finer with the increasing content of PTMC. In vitro drug release studies demonstrated an initial rapid release of shikonin followed by a plateau after 11 h. It was found that the release behavior could be tailored by the PCL/PTMC blend ratio and drug-loading content. Moreover, the free radical scavenging activity and the antibacterial effects of the shikonin-loaded fiber mats indicated that it could act not only as a drug delivery system but also in the treatment of wound healing or dermal bacterial infections.