Tunable hollow microspheres with a loading capacity of calcium phosphate nanoparticles as cell carriers: Effect of temperature and preparation conditions on microstructure

Injectable cell microcarriers have been widely studied in tissue engineering to fill any irregular defects. In this study, an emulsion method with different preparation conditions including oil phase concentration, internal water phase concentration, and their volume ratio was used to achieve microspheres with a hollow structure. The effect of external water phase (W-2) temperature on the surface porosity was studied, and the results showed that by increasing W-2 temperature, the size and density of microspheres' surface porosity were increased. Calcium phosphate nanoparticles (CPNPs) were loaded into hollow polymeric microparticles (HPMPs) through the surface porosity, and alizarin red staining indicated a core-shell structure for the optimal sample. Human adipose mesenchymal stem cells could spread and adhere to the microspheres' surface and maintain their morphology. Based on these results, CPNPs loaded HPMPs can introduce as a cell delivery system for bone tissue engineering applications. (c) 2020 Elsevier B.V. All rights reserved.