Regulation of micro/nano topography and porosity in biomimetic 3D-printed calcium phosphate ceramic scaffolds for enhanced bone regeneration

Abstract Biphasic calcium phosphate (BCP) scaffolds were developed with the pivotal goal of further biomimicking natural bone tissue and enhancing personalized and accurate repair to fulfill the needs of regenerative medicine. 3D-printed BCP ceramics were extensively utilized in bone repair because of their customizable attributes and excellent biocompatibility. However, 3D printing technology and high-temperature sintering led to the absence of microporous structure and surface nanostructure in the scaffolds, which could hinder protein adsorption, osteogenic differentiation and bone regeneration. In this work, biomimetic BCP scaffolds featuring adjustable porosity and surface micro/nano topography were created by integrating 3D printing technology with a hydrothermal process. These BCP scaffolds had abundant micropores and were distributed needle-like whiskers and hollow-tube whiskers, which demonstrated special physical and biological properties. Compared with scaffolds sintered at high temperature, these BCP scaffolds possessed higher porosity and smaller grain size, thereby enhancing specific surface area (SSA), ions release, the adsorption capacity of protein and facilitating the osteogenic differentiation in vitro. In the rat cranial defect model, it was manifested that biomimetic BCP scaffolds could enhance in situ bone regeneration and showed significant osteoconductivity and osteoinductivity in vivo, which demonstrated the promise for deployment in bone tissue engineering and regenerative medicine.