Surface Characterization of Calcium Phosphates
EMSL Project ID
19851
Abstract
Heterogeneous nucleation is important in the development of biominerals such as bone, teeth and mollusk shells, but often, initial nucleation events are not understood at a mechanistic level(1). It is generally agreed that proteins play a vital role in the nucleation event, however, the specific protein is often not identified. The very well studied enamel biomineral is one of the most highly ordered mineralized tissues(2) and is a good example of biomineral system with a nucleation event that is not well characterized. Amelogenin constitutes 90% of the protein present in developing enamel and as such, roles in nucleation and crystal regulation have been proposed(3),(4, 5). The ability of amelogenin to control calcium phosphate crystal growth is demonstrated by numerous in vitro and in vivo experiments, reviewed recently by Moradian-Oldak(3). The calcium phosphate/protein interaction of the highly hydrophobic amelogenin is thought to be enhanced by the self-assembly of amelogenin into 20 nm nanospheres(2, 6), exposing the charged amino acids on the nanosphere surface(6, 7) for calcium phosphate interaction. In spite of the evidence for hydroxyapatite (HAP) crystal interactions and though it is present at the site of initial enamel crystal formation(5), there is little direct evidence of amelogenin as a nucleator(5). The observation that nucleation was physically removed from the dentine in vivo led authors to suggest amelogenin as one of several possible nucleators(4), but later in vitro nucleation experiments in gels demonstrated no nucleating ability(8). To our knowledge, we report the first direct evidence that the amelogenin protein is capable of nucleating calcium phosphate mineral(9). The demonstration of heterogeneous nucleation directly from solution offers a new approach to addressing fundamental questions of nucleation.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2006-08-24
End Date
2007-08-08
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members