Biomaterials, inspired? - David Bradley
Nature is the mother (or father) of the toughest, strongest, most flexible, energy and atom efficient, materials. As such, lowly scientists and their engineering compatriots in the realm of materials are perpetually in awe, whether testing the porous and lightweight nature of bird bones, the almost endless corrals of coral skeletons, or seemingly superhydrophobic leaves. If only they could emulate these complex and yet simple structures, the fractal forms, and the generous porosity in the materials they construct and test in laboratories across the world.
There are two schools of thought when it comes to biomaterials. The first is simply to take inspiration from nature, to try to emulate the myriad array of materials using synthetic methods. Many new materials and structural forms have emerged from such biomimicry including technologies that have strong, close-packed "honeycomb" structures, fluffy fibres like cotton, polymer resins that try their best to be wooden, and yet others that seek to copy the incredible strength to weight ratio of spider silk, the sheen of mother-of-pearl, or nacre, and of course, bone.
Taking inspiration makes sense. Almost every materials solution has emerged as a result of millions of years of evolution to best fit the conditions facing the organism that exploits a given structure. But, the other school of thought is one that does not recognise a need to emulate anything. Instead of bio-inspired materials, some researchers are adopting nature's processes to exploit biomaterials, to either extract wholesale the required mass or two allow natural systems and organisms to generate such materials in situ and to then use those biomaterials in essentially their raw state with limited processing or synthetic intervention.
A genetically modified brassica might produce a synthetic polymer, for instance, or microbes fermented to stretch out fibre faster than even the slickest of silk worms. Scaffolds for tissue engineering, surgical repair, and wound healing, for instance, might be grown, perhaps as hybrid biomaterials, but mostly without the need to emulate nature, instead simply to engage it to work for us. Elsevier's Biomaterials journal shows a nice array of biomaterials published in 2011 [http://about.elsevier.com/media/Biomaterialsposter1111.pdf] There are many more examples being employed in medicine for treatment, diagnostics, and experimental surgical techniques in the form of materials for prosthetics. The notion of an all-natural kidney or heart, for instance, is no longer a concept from far-future science fiction but is something that is well within our grasp thanks to developments in biomaterials.
In terms of engineering the mineralization processes used by marine organisms are being modified and hybridised to create biomaterials that are certainly more than mimics, they are nature in the lab exemplified and are allowing materials scientists to engineer at the nanoscale by recruiting biology directly. Self-assembly from specific mixtures of ingredients, and the preservation of the natural hierarchy are key to success and require insight and intervention to produce synthetic nature rather than a natural impression.
David Bradley blogs at http://www.sciencebase.com and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
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Posted 11/07/2012 by Materials Today
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