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SUMMARY:From Confinement to Composites:  Bio-inspired Crystallisation - Fi
 ona Meldrum\, Uni of Leeds
DTSTART:20101021T103000Z
DTEND:20101021T113000Z
UID:TALK26483@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Biominerals exhibit many remarkable features which ensure that
  they are optimised for their particular function\, including complex morp
 hologies\, hierarchical organisation and superior mechanical properties.  
 Further\, unlike their synthetic counterparts\, biominerals are produced u
 nder mild reaction conditions.  It is envisaged that elucidation of the ke
 y strategies employed by organisms to produce biominerals will provide ins
 piration for the design and fabrication of new materials.  This talk will 
 focus on two key features of biominerals – that these structures form wi
 thin constrained reaction environments rather than in bulk solutions\, and
  that they are typically composite structures where organic macromolecules
  are embedded within inorganic crystals.  Biological systems are based on 
 compartmentalisation\, and the formation of biominerals is no exception.  
 We are currently investigating a series of systems including crossed cylin
 ders\, track-etch membrane pores and droplet arrays which offer confinemen
 t from the nanometer to the micron scale\, and experiment demonstrates tha
 t confining the reaction volume can significantly affect crystal nucleatio
 n and growth processes.  The composite structure of crystalline biomineral
 s is also fascinating\, especially when it is considered that recrystallis
 ation is a common technique for purifying crystalline materials.  Experime
 nts are being carried out to better understand how such composite crystals
  form\, using the entrapment of polymer particles within calcite single cr
 ystals as a model system.  We demonstrate that very high levels of entrapm
 ent can be achieved\, generating crystals occluding over 20 vol% of partic
 les\, according to the particle surface chemistry and the reaction conditi
 ons.  High resolution transmission electron microscopy (TEM) is used to vi
 sualise how the particles are embedded within the calcite lattice.  That s
 uch composite crystals show modified properties from pure calcite is also 
 shown through nanoindentation studies.  
LOCATION:Open Plan Area\, BP Institute
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