Preparation, antioxidant, antibacterial, and in vivo evaluation of pomegranate flower extract nanofibers based on thiolated chitosan and thiolated gelatin for treating aphthous stomatitis

Recurrent aphthous stomatitis (RAS) is a common condition that manifests as ulcerative lesions in the oral mucosa. In this study, bilayer, mucoadhesive nanofibers loaded with pomegranate flower extract (PFE) were prepared using thiolated gelatin (TGel) and thiolated chitosan (TCS) as the active layer and drug-free polycaprolactone (PCL) as the backing layer. Gelatin (Gel) and chitosan (CS) were successfully thiolated (proven by Ellman's assay, solubility, 1H NMR, FTIR, Raman spectroscopy, and XRD) and electrospun into active nanofibrous layers with a diameter of 356.9 nm. The in vitro release assay showed extended release of PFE, reaching about 57 % drug release in 48 h, fitted to the Korsmeyer-Peppas kinetics. FTIR, Raman spectroscopy, and XRD also showed the characteristic peaks of the nanofibers and their components. The nanofibers also exhibited significant hydrophilicity (contact angle of 47-49 degrees), mucoadhesion (432.7 Pa), antioxidant capabilities (93.3 +/- 0.2 %), and antibacterial effects against Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, PFE-loaded thiolated nanofibers significantly accelerated wound healing and epithelial tissue regeneration in vivo, reducing the ulcer area from 187 +/- 19 mm on the 1st day to 68 +/- 6 on the 7th day. Overall, bilayer PFE-loaded nanofibers based on TCS and TGel showed promising potential for treating RAS.