Silk fibroin processing and thrombogenic responses

Silkworm-derived fibroin, which constitutes the core of the silk filament, is an attractive protein-polymer for biomedical applications. Fibroin can also be processed into a variety of 2-D and 3-D formats to match morphological and structural features to specific applications. The focus of the present research was to correlate the structure of silk fibroin-derived biomaterials with plasma protein adsorption, platelet activation and inflammatory cell (THP-1 cell line) adhesion and activation. The amino-acid composition of the two types of silk studied influenced the crystallinity of the films, hydrophobicity, surface roughness and biological interactions. Protein adsorption was lower on samples with the higher crystallinity and hydrophobicity, in particular the chemotactic factors (C3a, C5a, C3b), while other proteins such as fibrinogen were comparable in terms of adsorption. As a consequence, platelets and immune cells responded differently to the various films obtained by following different processing protocols and stabilized by different methods (methanol or water vapour) in terms of their adherence, activation, and the secretion of inflammatory mediators by monocytes. The data presented here demonstrate that bioactivity can be influenced by changing the chemistry, such as the source of silk protein, or by the specific process used in the preparation of the materials used to assess biological responses.