By utilizing small molecules and proteins to modulate crystal nucleation and growth, living organisms produce single nanocrystals and nanocrystal composites that exhibit control over the location, phase and crystallographic orientation of the nuclei, as well as the morphology and kinetics of the growing crystal. A common paradigm for interpreting this phenomenon is that the stereochemistry of the growth modifiers is matched to that of a particular crystallographic plane that would not otherwise be expressed during nucleation or growth in pure environments. This paradigm has been generally referred to as stereochemical recognition. Using in situ AFM, we have investigated nucleation and growth in a number of crystal-modifier systems. Molecular modeling was also used to calculate the binding energies for modifiers attached to crystal faces and steps. The systems examined include carbonates, phosphates, oxalates, and pthalates grown in the presence of inorganic ions, amino acids, organic dyes, and proteins. We show that, while the exact mechanism of growth modification is different in each system, the one feature that they have in common is that the important molecular-scale interaction that gives rise to growth modulation is between the molecular modifier and specific atomic steps on existing crystal planes.
Journal: TechConnect Briefs
Volume: 1, Technical Proceedings of the 2003 Nanotechnology Conference and Trade Show, Volume 1
Published: February 23, 2003
Pages: 7 - 9
Industry sectors: Advanced Materials & Manufacturing | Medical & Biotech