Crystallization of calcium phosphate templated by alpha-amino acids depending on their composition, chain length, and enantiomerism

alpha -Amino acids showed a characteristic templating effect on the crystal lization of calcium phosphate at pH 7.0. Neutral but polar or basic group b earing amino acids yielded hydroxyapatite predominantly, whereas n-alkyl am ino acids produced octacalcium phosphate (OCP) leading to an increase in cr ystallinity, expansion in cell volume and/or interlayer contraction dependi ng on their chain length and enantiomerism. Aspartic acid, a short chain ac idic amino acid, formed an amino acid complexed OCP with a significant incr ease of its crystallinity in the order of D approximate to L < DL, in contr ast to the partial formation of a similar composite for glutamic acid.