Design of a composite wound dressing : combining an electrospun fleece with a free-standing multilayer film

Abstract

Chronic skin wounds place a heavy burden on patients and healthcare systems. To address this problem, we have developed a novel composite material consisting of an electrospun fleece and a free-standing multilayer film that combines the wound healing benefits of both materials. In detail a combination of spray coating and electrospinning is used to create a layer-by-layer film on top of a gelatin fleece, with a final thickness of about 1 mm. A gelatin fleece is partially crosslinked in formaldehyde vapor and 30 pH-sensitive bonding bilayers of partially oxidized hyaluronic acid (HA) and chitosan, followed by 120 bilayers of alginate and chitosan are sprayed on top. The resulting composite is crosslinked with genipin. Uncrosslinked and genipin crosslinked composites are compared to the unprocessed fleece and free-standing multilayer film. The spray coating method produces a stable composite, allows a fast growth of the film part und most importantly retains the nano-topography of the fleece side as confirmed by electron microscopy, profilometry, nano-tomography and dynamic mechanical analysis. To test biocompatibility, cell proliferation experiments with human dermal fibroblasts and THP-1 derived macrophages are performed, proliferative assays are accompanied by immunohistochemical staining and a pro/anti-inflammatory cytokine assay. The composite shows no cytotoxicity and is biocompatible in vitro. Furthermore, the electrospun fibers of the fleece act as a scaffold to highly promote cell adhesion and proliferation, while the modular design of the multilayer free-standing film, in combination with genipin crosslinking, allows the tuning of the anti-inflammatory effect by HA. Overall, the composite seems to be a promising starting point for the design of a novel wound dressing.