Glutamic acid concentration dependent collagen mineralization in aqueous solution

Abstract

The aim of this research is to evaluate the effects of glutamic acid (Glu) on the process of collagen mineralization, the structure and property of mineralized composites. Collagen mineralization was initiated by introducing PBS to blended solutions containing 1 mg/mL collagen, 6 mmol/L calcium and Glu ranged from 0 to 550 mmol/L. The kinetic curves and quantitation analyses showed that Glu could delay the collagen mineralization, and reduce the crystalline size and the amount of hydroxyapatite. With the Glu concentration increased from 50 to 200 mmol/L, the collagen self-assembly was promoted, resulting in the improvement of hardness and thermal stability of mineralized composites. However, further increase in the Glu concentration to 400 mmol/L or above would significantly inhibit the self-assembly of collagen and reduce the hardness and thermal stability of mineralized composites. Scanning electron microscopy revealed that the diameter of collagen became thicker as the Glu concentration increased. Moreover, hydroxyapatite with spherical morphology was uniformly dispersed and well combined with collagen fibril at Glu concentration of 200 mmol/L. These results may provide a broader understanding of the potential mechanism of biomineralization and be critical in the design of biomimetic scaffolds for bone tissue engineering.