Fibroin: an example of hierarchy and conformation dominated biological behaviour

Silk-fibroin proteins have quite recently attracted wide attention as bioactive matrices for biomedical applications. In vitro and in vivo studies have demonstrated the ability of fibroin to favourably interact with cells and the advantageous use of fibroin scaffolds to engineer the repair and regeneration of different types of tissues. Cell seeded or unseeded scaffolds have been proposed and successfully tested for soft and hard tissues repair, in form of gels, sponges, fibres or films, adapted to a variety of repair sites and clinical needs. As for other natural polymers, silk possesses a complex hierarchical structure that is bottom-up assembled, where each pattern/conformation can be correlated to specific biological functions or physical properties. Self-assembling and resulting conformation of silk fibroin depend however on silk source and processing conditions, that in turn affect the material both biological and physical behavior. This fact adds complexity to the understanding and control of the materials/biological system crosstalk and should be carefully checked and taken into account when biologically engineering reproducible scaffold. The presentation will be focused on the interactions between silk fibroin and cells. Specific hints on the effect of processing on silk conformation and function-structure relationships will be discussed in light of fabricating responsive devices applicable in regenerative medicine.