PDGF and VEGF-releasing bi-layer wound dressing made of sodium tripolyphosphate crosslinked gelatin-sponge layer and a carrageenan nanofiber layer

Abstract

The use of dressings is one of the most common methods for wound treatment. Since most single-layer dressings cannot mimic the hierarchical structure of the skin well, multi-layer dressings have been considered. In this study, a bilayer dressing was fabricated using a gelatin sponge layer cross-linked with sodium tripolyphosphate (Gel-STPP) and a layer of carrageenan nanofibers containing platelet-rich fibrin (Carr-PRF). Chemical in-teractions between the two layers were characterized by FTIR, and the microstructure was visualized by SEM. It was found that the presence of Carr-PRF nanofiber layer increased tensile strength by 12.96 (from 0.216 +/- 0.015 to 0.268 +/- 0.036 MPa) and elastic modulus by 56.70 (from 0.388 +/- 0.072 to 0.608 +/- 0.029 MPa) compared to Gel-STPP sponge. Gel-STPP/Carr-PRF wound dressing had a 45.76 +/- 4.18 degradability after 7 days of immersion in phosphate buffered saline (PBS). PRF-containing bilayer wound dressing was able to sustainably release growth factors over 7 days. The Carr-PRF nanofiber layer coated on Gel-STPP sponge was an ideal environment for adhesion and proliferation of L929 cells. Gel-STPP/Carr-PRF bilayer dressing out-performed the other tested samples in terms of angiogenic potential. Average wound closure was 94.21 +/- 2.06 in Gel-STPP/Carr-PRF dressing treated rats after 14 days, and based on the histopathological and immunohis-tochemical examinations, the Gel-STPP/Carr-PRF dressing group augmented full-thickness wound healing, keratin layer and skin appendages formation after 14 days.