Affiliations: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, Japan | Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu, Japan | Graduate School of Engineering, Nagoya University, Nagoya, Japan
Note: [] Address for correspondence: Toshiki Miyazaki, Associate Professor, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka 808-0196, Japan. Tel./Fax: +81 93 695 6025; E-mail: [email protected]
Abstract: Apatite–polymer composites mimicking specific structure of natural bone are promised as bone substitutes with moderate flexibility able to be fabricated into desired shapes as well as bone-bonding bioactivity. In order to precipitate the apatite on polymer surfaces, aqueous processing using solution supersaturated to the apatite has been attracting as much attention. Polyglutamic acid (PGA) is a promised candidate of the polymer, since it has high apatite-forming ability owing to abundant carboxyl groups able to trigger the heterogeneous apatite nucleation. Although combination of PGA with different molecular weight is expected to provide design of organic–inorganic composites with moderate bioresorbability, precise relationship between the molecular weight of the PGA and its apatite-forming ability has been remained unclear. In the present study, PGA hydrogels with different molecular weight were prepared by covalent cross-linking using ethylenediamine. Difference in apatite formation in simulated body fluid (SBF) was interpreted in terms of their chemical structure. It was found that hydrogels prepared from PGA with higher molecular weight showed tendency to have higher apatite-forming ability. It was attributed to high content of the carboxyl group remaining on the hydrogel due to low degree of the cross-linking.
