Multifunctional Bi-layer collagen nanofiber-collagen/PLLA/Zataria multiflora essential oil nanofiber for wound healing: Antibacterial, antifungal and antioxidant properties

Multi-layer electrospun structures have attracted interests as multifunctional wound dressings. In the present study, a double-layered nanofibrous construct was prepared out of pure type I collagen nanofibers (as the inner layer) and collagen/PLLA/Zataria Multiflora essential oil (as the outer layer). Extracted essential oil was analyzed by GC–Mass Spectrometry. Bi-layers were characterized by SEM, ATR-FTIR and XRD. Water contact angle and swelling studies demonstrated hydrophilicity and a high water absorption capability (1504% of the initial weight) of the nanofibers, respectively. Also, the essential oil showed a strong antioxidant activity (IC50: 7.4 ppm). Cumulative release profile of the essential oil from nanofibers illustrated a burst release in about 120 min and then, a sustained release up to 72 h. Broth micro-dilution, disk diffusion and AATCC 100 assays were performed and the bi-layer dressings exhibited strong antibacterial activity (against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli) and antifungal activity against 4 Candida species. Viability of the fibroblast cells on the obtained structures was evaluated by alamar blue and live/dead assays that confirmed appropriate cyto-compatibility of the nanofibers. Therefore, biocompatible double-layered constructs with strong antimicrobial, antioxidant and water absorption capabilities would be promising as potential wound dressings.