Role of amino acids in the regulation of crystallinity of hydroxyapatite

摘要

Hydroxyapatite (HAp) was synthesized in the presence of various types of amino acids; glycine (Gly), alanine (Ala), arginine (Arg), aspartic acid (Asp) and glutamic acid (Glu), as components of proteins, in order to investigate their effects on hydroxyapatite crystals. Glycine and alanine are neutral, arginine is a basic and aspartic acid and glutamic acid are acidic amino acids. Furthermore, we estimated the crystallinity and solubility of synthesized HAp. Analysis of X-ray diffraction demonstrated that all of the synthesized HAp had a typical X-ray diffraction patterns of HAp, whereas the crystallinity of HAp synthesized in the presence of either aspartic acid (HAp_(Asp)) and glutamic acid (HAp_(Glu)) decreased with the increase of the amounts of these acidic amino acids present. The solubility of HAp_(Asp) and HAp_(Glu) increased significantly with the increase of the amounts of acidic amino acids present. The lower crystallinity of HAp_(Asp) and HAp_(Glu) observed in the current study was likely due to the adsorption of these amino acids on HAp. These results suggest that amino acids may play a major role in the regulation of crystallinity and solubility of HAp which is frequently used as a biomaterial for hard tissue diseases management.