  Materials that are strong, ultra-light weight and tough are in demand for a
range of applications, requiring architectures and components carefully
designed from the micrometer down to nanometer scales. Nacre-a structure found
in many molluscan shells-and bone are frequently used as examples for how
nature achieves this through hybrid organic-inorganic composites.
Unfortunately, it has proven extremely difficult to transcribe nacre-like
clever designs into synthetic materials, partly because their intricate
structures need to be replicated at several length scales. We demonstrate how
the physics of ice formation can be used to develop sophisticated porous and
layered-hybrid materials, including artificial bone, ceramic/metal composites,
and porous scaffolds for osseous tissue regeneration with strengths up to four
times higher than those currently used for implantation.
