Promotion of fibroblast activity by coating with hydrophobins in the β-sheet end state

Hydrophobins such as SC3 and SC4 of Schizophyllum commune self-assemble into an amphipathic film at hydrophilic/hydrophobic interfaces. These proteins can thus change the nature of surfaces, which makes them attractive candidates to improve physio- and physico-chemical properties of implant surfaces. At a hydrophobic solid, assembly of the hydrophobin is arrested in an intermediate state, called the α-helical state. The conversion to the stable β-sheet end state can be induced by treating the solid at elevated temperatures in the presence of detergent. We here show that SC3 and SC4 in the α-helical state homogeneously cover Teflon sheets when coating was performed at 20°C. However, when the protein was adsorbed at 80°C aggregates were shown to bind tightly to the adsorbed hydrophobin film. The transition to the β-sheet state created pores of about 50nm in the SC3 and SC4 coatings when coating was performed at 20°C. Cell growth and morphology on SC4 coatings was better than on SC3. In case of both hydrophobins, fibroblast growth and morphology was not influenced by the coating temperature or the conformation of the protein. However, in contrast to the α-helical state, the β-sheet state of both SC3 and SC4 hardly, if at all, affected mitochondrial activity.