Growing seashells in the lab
10 Oct 2011 by Evoluted New Media
Synthetic crystals which mimic the structure and properties of naturally occurring biominerals such as seashells and bone have been created under environmentally-friendly conditions by a team of UK scientists.
A key feature of biomaterials is their nanocomposite structure which derives from the inanimate association of organic molecules with a mineral host – usually calcium carbonates. This results in incredibly hard structures, with mechanical properties rivalling man-made material like ceramics.
Understanding how biology can perform such precision engineering in water at ambient temperatures is of interest to scientists who hope to apply this principle to the design and production of synthetic materials with greener credentials.
A team led by Professor Fiona Meldrum at the University of Leeds has successfully created artificial biominerals that exhibit similar properties to biomaterials. The synthetic crystals exhibit analogous texture and defect structure to biogenic calcite crystals, and are harder than pure calcite.
“What we found is that the artificial biomineral we have created is actually much harder than the pure calcite mineral because it is a composite material – where you add something to a hard substance to create something even harder than either of the constituent parts,” said Meldrum.
Calcite crystals were grown in the presence of synthetic nanoparticles, which act as artificial proteins which are incorporated into the architecture of the crystal as it grows to create a composite material. Researchers tested the mechanical properties of the composite using a nanoindenter – a small chisel-like tool that can prod a material and record its response to a force.
“This method of creating synthetic biomaterials gives us a unique insight into the structure of these incredible materials and the way the organic molecules are incorporated in the crystal structure at a microscopic level,” said Meldrum. “We can then relate this microscopic structure to the mechanical properties of the material.”
This method provides a unique model for understanding biomineral formation and an insight into the mechanism of occlusion of biomacromolcules within single crystals. It also illustrates the relationship between macroscopic mechanical properties of a crystal and its microscopic structure.
The research also involved scientists at the Universities of Sheffield, Manchester and York, and a team from the Israel Institute of Technology. The findings were published in Nature Materials.
An artificial biomineral formed by incorporation of copolymer micelles in calcite crystals.
