Achieving tunable and interconnected porosity of biomimetic apatite scaffolds through Pickering emulsion templates

Synthetic apatitic calcium phosphates are widely used to develop biomaterial devices due to their excellent biological properties. The aim of this study was to develop nanocrystalline apatitic calcium phosphates (NCA) bioceramics with tunable porosity (size of pores, total porosity percent) to preserve surface reactivity and improve bioactivity based on an original manufacturing process. For this purpose, a low-temperature method of elaboration via Pickering emulsions was used and the influence of several process parameters (emulsion-to-gel weight ratio and formulation of the emulsion) on the properties of the bioceramics was studied. This process allows the formation of NCA crystals-based materials as shown by X-ray diffraction and FTIR spectroscopy. The initial conditions of the emulsion control the final porous structure evidenced by X-ray micro-computed tomography: if the diameter of the droplets of the starting emulsions controls the pores size, it does not influence the total porosity percent and interconnection which depend only on the emulsion-to-gel ratio. The viability of the scaffolds was assessed using the osteoblast cell line in two steps: cell adhesion assays and photobiomodulation. None of the scaffolds showed cytotoxic effects. With the proposed process, scaffolds were obtained with controlled pore size and interconnected pores, composed of reactive biomimetic apatites with mechanical properties suitable for applications in filling bone defects and good osteoblastic adhesion and proliferation properties.