3D porous HA/TCP composite scaffolds for bone tissue engineering

Calcium phosphates (apatites) are considered as a research frontier for bone regeneration applications by virtue of similarity to the mineral constituent of bone, suitable biocompatibility and remarkable osteogenesis ability. In this regard, the biodegradability and mechanical properties of monophasic apatites, typically hydroxyapatite (HA) and tricalcium phosphate (TCP), are imperfect and do not fulfill some requirements. To overcome these drawbacks, 3D porous HA/TCP composite scaffolds prepared by conventional and more recently, 3D printing techniques have shown to be promising since their bioperformance is adjustable by the HA/TCP ratio and pores. Despite the publication of several reviews on either 3D porous scaffolds or biphasic calcium phosphates (BCPs), no review paper has to our knowledge focused on 3D porous BCP scaffolds. This paper comprehensively reviews the production methods, properties, applications and modification approaches of 3D porous HA/TCP composite scaffolds for the first time. In addition, new insights are introduced towards developing HA/TCP scaffolds with more impressive bioperformance for further tissue engineering applications, including those with different interior and exterior frameworks, patient-specific specifications and drugs (or other biological factors) loading.