Self‐Hardening Microspheres of Calcium Phosphate Cement with Collagen for Drug Delivery and Tissue Engineering in Bone Repair

Self‐hardening microspheres were developed as a 3‐dimensional (3D) matrix for bone regeneration. α‐tricalcium phosphate (α‐TCP)‐based calcium phosphate cement (CPC) was mixed with collagen and emulsified to produce spherical microparticulates, during which the spheres could be hardened within minutes. The immersion of the microspheres in a fluid allowed the transformation of the α‐TCP into bone mineral‐like hydroxyapatite. Biological protein could be easily encapsulated within the microspheres and was released in a sustained manner over a month. Bone cells were shown to adhere and grow actively upon the CPC‐collagen microspheres. The newly developed CPC‐collagen microspheres with self‐hardening property may be potentially useful as a 3D matrix for bone regeneration.