Crystallization of Calcium Phosphate Templated by α-Amino Acids Depending on Their Composition, Chain Length, and Enantiomerism

Abstract α-Amino acids showed a characteristic templating effect on the crystallization of calcium phosphate at pH 7.0. Neutral but polar or basic group bearing amino acids yielded hydroxyapatite predominantly, whereas n-alkyl amino acids produced octacalcium phosphate (OCP) leading to an increase in crystallinity, expansion in cell volume and/or interlayer contraction depending on their chain length and enantiomerism. Aspartic acid, a short chain acidic amino acid, formed an amino acid complexed OCP with a significant increase of its crystallinity in the order of d ≈ l < Dl, in contrast to the partial formation of a similar composite for glutamic acid.