Synthesis and rheological evaluations of novel injectable sodium alginate/ chitosan-nanostructured hydroxyapatite composite bone pastes

In this paper, nanostructured carbonated hydroxyapatite powder was synthesized using biomimetic method. Physical properties and morphological features of the powder was studied using appropriate techniques such as BET, TEM, XRD and FTIR. The powder was separately mixed with 3 wt. % solutions of either sodium alginate or chitosan to form different pastes. Rheological behavior of the pastes in oscillation mode was measured. Results showed that mean particle diameter and surface area of the powder were 3.9 μm and 154.8 m/g, respectively. According to dynamic rheological evaluations, all pastes exhibited shear thinning behavior with linear viscoelastic limitations, although paste containing sodium alginate displayed broader linear viscoelastic range than others. Increasing concentration of sodium alginate or chitosan led to increment of viscosity, meanwhile sodium alginate produced a material of higher viscosity than did chitosan. When sodium alginate was employed, lower force was required for injection. Totally, these bioactive pastes potentially can be used for the treatment of hard tissues.