Biomimetic synthesis of platelet-shaped hydroxyapatite mesocrystals in a collagen mimetic peptide–PEG hybrid hydrogel

•A collagen mimetic peptide–PEG hybrid hydrogel was used for crystal growth.•Biomimetic synthesis of hydroxyapatite was achieved by double diffusion.•The hydroxyapatite was characteristic of mesocrystals.•The gel-mediated strategy is promising both fundamentally and practically.

Collagen mimetic peptide–PEG hybrid hydrogels have emerged as a new class of synthetic collagen mimics with well-defined structure and composition. Herein, we probed the versatility of a collagen mimetic peptide–PEG hybrid hydrogel for biomimetic synthesis of hydroxyapatite. This was achieved by double-diffusion, where ion precursors diffused from opposite directions into the hydrogel to form a precipitant band with hydroxyapatite minerals. Morphological and crystallographic analyses revealed these minerals adopted platelet-shaped morphology with cobble-like subunits of mesoscopic size and exhibited single crystal-like scattering patterns, which was characteristic of mesocrystals. The gel-mediated strategy in our study may be applicable to study mechanisms concerning hydroxyapatite mesocrystals formation and to construct functional materials.