Biomimetic bone calcium phosphate-based scaffolds fabricated via ceramic vat photopolymerization: Effect of porosity, sintering temperature, mineralogical phases and trace elements on the osteogenic potential

Abstract

In response to the growing demand for novel approaches in bone repair, scaffolds that mimic natural bone microstructure and mineralogical composition were developed using a ceramic vat photopolymerization (VPP) method. Due to varying reported results regarding appropriate microstructural characteristics, this study aimed to clarify the best pore size distribution and porosity among the tested scaffolds for an efficient osteogenic response. Scaffolds based on hydroxyapatite both support new bone formation by osteoblasts and can be resorbed by osteoclasts. An average pore size of ∼400 μm and porosity of 45.61% showed the best mechanical properties and osteogenic response, allowing cell penetration, and supporting cell-cell interactions and the differentiation process. When Sr,Mg,Zn-substituted hydroxyapatite is used for scaffold fabrication, the required high sintering temperatures lead to the transformation of hydroxyapatite into β-tricalcium phosphate, a common calcium phosphate used in bone tissue engineering. However, the new mineralogical phase results in different surface properties that do not support appropriate cell attachment on scaffolds with higher negative surface charge and lower wettability. This work emphasizes the potential of ceramic VPP in the development of biomimetic scaffolds that mimic natural bone tissue and provides guidelines on which microstructural characteristics are appropriate for efficient bone regeneration. This study also raises new questions regarding cell attachment on β-tricalcium phosphate-based scaffolds, which are currently under exploration.