The fabrication of biomimetic scaffolds for soft tissue engineering is a field in continuous expansion that focuses on new routes to prepare nanofibers from various proteins.
For fibrinogen, we developed the process of salt-induced self-assembly to prepare nanofiber scaffolds that resemble the porous architecture of native fibrin. Fibrinogen nanofibers supported co-cultivation of human fibroblasts and keratinocytes for 14 days. Both cell types maintained their native phenotype as indicated by vimentin and cytokeratin-14 expression for fibroblasts and keratinocytes, respectively (see Fig. 1). Fibroblasts displayed their characteristic wound healing phenotype, characterized by fibronectin expression. Blood platelets adhered strongly on fibrinogen nanofibers with large spreading areas, and their procoagulant activity was minimized. The growth of E. coli bacteria was significantly reduced on fibrinogen nanofibers in comparison to agar controls, and no bacteria penetrated through the fibers. Interestingly, nanofibrous fibrinogen scaffolds, depending on the substrate, can detach or remain immobilized, which offers a wide range of applications.
For collagen we introduced a new method to prepare free-standing nanofiber scaffolds on silanized alumina textiles. Following self-assembly and crosslinking, nanofibrous collagen scaffolds autonomously rolled up into tubes with an inner diameter of 2-4 mm that subsequently detached from the textiles (see Fig. 2). In previous studies we already reported excellent biocompatibility of crosslinked collagen fibers that induced fibroblast and keratinocyte proliferation and prevented E. Coli penetration into alumina nanopores. Hence, this new roll-up routine offers great potential to prepare tubular collagen scaffolds, for instance for blood vessel replacement. For applications in wound healing, we will now combine both methods to produce free-standing composites of collagen and fibrinogen nanofibers that enable the co-cultivation of different cells from both sides.