Silk fibroin-polyurethane scaffolds for tissue engineering

Silk fibroin (SF) is a highly promising protein for its surface and structu ral properties, associated with a good bio- and hemo-compatibility. However , its mechanical properties and architecture cannot be easily tailored to m eet the requirements of specific applications. In this work, SF was used to modify the surface properties of polyurethanes (PUs), thus obtaining 2D and 3D scaffolds for tissue regeneration. PUs wer e chosen for their well known advantageous properties and versatility; they can be obtained either as 2D (films) or 3D (foams) substrates. Films of a medical-grade poly-carbonate-urethane were prepared by solvent casting; PU foams were purposely designed and prepared with a morphology (porosity and cell size) adequate for cell growth. PU substrates were coated with fibroin by a dipping technique. To stabilize the coating layer, a conformational c hange of the protein from the alpha -form (water soluble) to the beta -form (not water soluble) was induced. Novel methodology in UV spectroscopy were developed for quantitatively anal yzing the SF-concentration in dilute solutions. Pure fibroin was used as st andard, as an alternative to the commonly used albumin, allowing real conce ntration values to be obtained. SF-coatings showed good stability in physiological-like conditions. A treat ment with methanol further stabilized the coating. Preliminary results with human fibroblasts indicated that SF coating promot e cell adhesion and growth, suggesting that SF-modified PUs appear to be su itable scaffolds for tissue engineering applications. (C) 2001 Kluwer Acade mic Publishers.