Formation of vaterite regulated by silk sericin and its transformation towards hydroxyapatite microsphere

●Soluble silk sericin could affect the polymorph transformation of CaCO3.●Homogeneous hydroxyapatite microspheres are fabricated using vaterites as templates.●Obtained hydroxyapatite copy faithfully the shape and size of vaterite.●The microwave method accelerates the transformation from vateriate to hydroxyapatite.●The work offers a simple method for the preparation of hydroxyapatite microspheres.

The influence of soluble silk sericin (SS) protein on the formation of CaCO3 particles was investigated and the CaCO3 particles were then used as a template to synthesize the hydroxyapatite microspheres. The SS showed a strong preference to the mineralization of vaterite and the fine controls over the shape, size and uniformity of vaterite were carried out by the variation of pH value and reaction time in the presence of SS. Using the vaterites as a template, the homogeneous and monodispersed hydroxyapatite microspheres, copying faithfully the shape and size of original vaterites, were fabricated under the assistance of microwave irradiation. The research may provide a feasible method for the fabrication of hydroxyapatite-based biomaterials with controllable configuration.