Engineering Increased Stability into Self-Assembled Protein Fibers

The design and engineering of self-assembled peptide-based materials is receiving increasing attention in materials science. This is partly because of the inspiration that biological materials provide to materials scientists; our improved ability to design, engineer and characterize peptides and proteins in general over the past decade; and the variety of potential applications for such materials in the broad areas of bionanotechnology and biotechnology. Potential applications for self-assembled peptide systems include components of smart and responsive materials, as biocompatible materials for surface engineering, and as templates for the growth and organization of organic and inorganic materials. One specific application is as a scaffolds for 3D cell culture and tissue engineering (TE). TE is a multidisciplinary field that encompasses aspects of chemistry, cell biology, and engineering. The ultimate aim of TE is to produce 3D cell cultures and fully functional tissues for applications in regenerative medicine. The current state-ofthe-art is to use biodegradable materials (often described as scaffolds)—which can either be preformed or assembled in situ—in combination with cells, with cell culture often being carried out in a bioreactor. Ideally, in this way, the combination of support, cell type, and conditions can be chosen to direct differentiation of cells down one lineage and, thence, the production of one tissue type. Our interest in this area has to been to design self-assembling, biocompatible materials for development as scaffolds for 3D cell culture. Gene expression in cells has been known for some time to be linked not only to chemical composition, but also to surface topography of scaffolds. Consequently, for 3D cell culture to be successful, scaffolds must mimic the native extracellular matrix (ECM) as far as possible. There is a vast array of available scaffolds for tissue engineering; they range from solid pre-formed polymer scaffolds, formed using heat fusion or adhesive techniques, to cell/scaffold hybrids with assembly of the scaffold encapsulating the cells. The native ECM is predominantly composed of a nonwoven mesh of fibrous proteins, such as collagen