Fabrication And Characterization Of Genetically Engineered Silk Elastin-Like Protein Films

Protein films are an important class of materials for applications in biomedicine and biotechnology.The rational design of protein polymer sequence and selection of customized cross-linking offers unique opportunities to engineer desirable functionalities into these materials.Here we report the fabrication of a series of genetically engineered silk-elastinlike protein(SELP)films with tunable physiochemical properties.The SELPs were recombinantly biosynthesized with different ratios of the silkto-elastin blocks and periodic cysteine residues incorporated in the elastin blocks.A disulfide cross-linking method was developed for the preparation of the SELP films under mild oxidative condition with a low concentration of hydrogen peroxide,in comparison with the physical cross-linking method with the use of organic solvent methanol.The film properties were characterized in terms of solubility,water absorption,film hydrophilicity,surface roughness,and biocompatibility.These results indicated that customized cross-linking was necessary to fabricate the SELP proteins with varying molecular features into smooth,water stable film materials that exhibited high cyto-compatibility to support growth of a mouse preosteoblast cell line.Interestingly,hydrogen peroxide oxidation was found to be a preferred cross-linking method for the cysteine-containing SELP with a low ratio of the silk-to-elastin blocks,while methanol treatment was suitable for fabricating SELP with a high ratio of silk-to-elastin blocks into very stable films with rougher surfaces.We anticipate that an appropriate combination of polymer design and cross-linking might be a useful strategy for the preparation of protein film materials for diverse potential applications.