Three major challenges for our ability to model the onset of crystal formation during biomineralisation will be addressed within this theme. These are to understand and characterise: (1) the amorphous precursor nanoparticles that have recently been shown to play an important role in the initial stages of CaCO3 deposition; (2) water of inclusion within amorphous carbonates and phosphates, which has been shown to affect subsequent crystal nucleation strongly; and (3) crystal nucleation and polymorph selection within individual amorphous nanoparticles. Major developments in modelling methodology, and experimental characterisation of carbonate and phosphate nanoparticles will be undertaken to meet these challenges.
Achievements so far, June 2013
- Development of reliable atomistic models for hydrated amorphous calcium carbonate (ACC) that reproduce experimental structures and show conformity across a vast range of initial structures and initialization protocols.
- Identification of two distinct states for CaCO3 nanoparticles smaller than ~2 nm, with proof of thermodynamic and mechanical (meta)stability for a dense , amorphous structure with only slightly higher free energy (~ 2 kBT) than the dynamically ordered low density clusters.
- Elucidation of a mechanism for water diffusion within hydrated ACC, and that now makes it possible to develop biased molecular dynamics methods to simulate the dehydration of ACC.
- Development of two new methods (“Ion Site Monte Carlo”, and “Intelligent Water Drop” global optimisation) for structures and morphologies of ionic nanoparticles.
- Initial studies of the effect of amino acids on nanoparticle structure and stability.