Novel polydopamine/halloysite nanotube-reinforced brushite calcium phosphate cement for bone regeneration with synergistic regulation of mechanical/osteogenic capacity

Bone regeneration remains a clinical challenge with limited bone substitutes. Brushite calcium phosphate cements (Bru-CPCs), possessing good bioactivity and biocompatibility, are one of the widely studied bone graft materials. However, their further application in the long-term remodeling of bone is limited by the low compressive strength. Adding additives has been a promising strategy to solve the above problem. Herein, halloysite nanotubes (HNTs) with a unique rod-like structure and excellent biocompatibility were chosen as reinforced materials to fabricate bone repair materials. Inspired by the adhesive proteins in mussels, we modified the HNTs' surface with polydopamine (PDA) to improve the inorganic-inorganic phase interfacial interactions between the HNTs and Bru-CPCs. Bru-CPCs, Bru-CPCs/1.5%HNTs and Bru-CPCs/1.5%HNTs@PDA were fabricated and the mechanical properties and biological activity of the bone repair materials were evaluated in detail. All the results indicated that Bru-CPCs incorporated with 1.5 wt% HNTs@PDA have good compressive strength and osteo-differentiation properties, making them a prospective biomaterial for bone-tissue repair.