Thin silk fibroin coating on electrospun fibers for sustained release of active compounds

• Published in: Journal of drug delivery science and technology 2024-06, Vol.96, p.105702, Article 105702
• Main Authors: Baranowska-Korczyc, Anna, Kamińska, Irena, Cieślak, Małgorzata
• Format: Article
• Language: English
• Subjects: Ciprofloxacin; Drug delivery system; Electrospinning; Policaprolactone; Silk fibroin; Sustained release
• ISSN: 1773-2247
• DOI: 10.1016/j.jddst.2024.105702

This study describes a method for producing a silk fibroin (SF) layer on fibrous structures formed by an amorphous polymer matrix for sustained drug diffusion. The presented model system is electrospun nanofibers of polycaprolactone (PCL) with ciprofloxacin (CIP). The nanofibers were covered with SF by immersion in its 0.2 wt% aqueous solution, which allows the forming on the nanofiber surface of a 50 nm layer. SF layer was crystallized by ethanol vapor and made SF insoluble in water for over 2 weeks due to an increase of β-sheet content in the protein secondary structure. SF does not affect the high surface-area-to-volume ratio of the fibers and makes them hydrophilic. The nanofibers reveal antibacterial properties against Gram-positive Staphylococcus aureus and -negative Klebsiella pneumoniae bacteria. The inhibition zone of bacteria growth after 24 h incubation is bigger for non-coated fibers indicating inhibition of the drug release by SF coating. Both kinds of fibers reveal the Fickian diffusion model of drug release, characterized by burst release for fibers non-covered with SF and sustained release for those covered with SF layer. The presented SF layer preparation method can facilitate the construction of future drug delivery systems and design materials with sustained release profiles. [Display omitted] •Silk fibroin layer on drug-containing fibers changes the drug release profile from burst to sustain release.•Silk fibroin layer on drug-containing fibers does not change the drug-release mechanism of Fickian diffusion.•A 50 nm silk fibroin layer is formed on electrospun fibers by dip-coating them in 0.2 wt% aqueous solution of the protein.•The silk fibroin layer becomes stable after crystallization and formation of β-sheets by ethanol vapor.•The wetting pre-treatment of an electrospun structure by water/isopropanol is necessary to permeate silk fibroin solution.