Protein crystals: How the weak become strong

Proteins are the bricks of life not only as molecular machines fulfilling many biochemical tasks and reactions but also as a class of material with an amazing diversity of properties. These different applications pose often contradictory requirements to the material design. The unique mechanical properties of spider silk rely on the existence of a composite structure of protein nanocrystals with the amino acids aligned in sheets β-sheet stacks in an amorphous matrix material. The smaller the crystal size, the more dominant shear contributions become, which is in contrast to systems where entropic contributions dominate the response. A combination of microfluidics, X-ray scattering techniques, biochemical analysis and molecular dynamics simulation techniques will be a promising route to teach the lessons needed to improve the engineering skills.