Novel microsphere-packing synthesis, microstructure, formation mechanism and in vitro biocompatibility of porous gelatin/hydroxyapatite microsphere scaffolds

In this study, three types of porous gelatin/HAp composite-based scaffolds were prepared and their microstructure, mechanical property, and in vitro biocompatibility were evaluated. FD-gelatin/HAp scaffolds were prepared via a conventional freeze-drying (FD) method, while DCPD-bound gelatin/HAp (DCPD-gelatin/HAp) microsphere scaffolds and HAp-bound gelatin/HAp (HAp-gelatin/HAp) microsphere scaffolds were prepared via the combined method of emulsion technique and novel microsphere-packing method. It was found that the microstructure and mechanical property of porous gelatin/HAp scaffolds were highly dependent on the preparation method and type of scaffolds. FD-gelatin/HAp scaffolds had few pores with a comparatively flat surface and had a compressive strength was 24 ± 1 MPa. DCPD-gelatin/HAp microsphere scaffolds had a porous structure with the average pore size of 121 ± 12 μm and had the compressive strength of 50 ± 3 MPa. HAp-gelatin/HAp microsphere scaffolds also had a porous structure with the average pore size of 190 ± 26 μm and had the compressive strength of 17 ± 4 MPa. In vitro biocompatibility was performed by culturing the osteoblast-like MC3T3-E1 cells with all types of scaffolds. The results showed that all types of scaffolds were biocompatible to support cell attachment and proliferation. However, a significant difference in cell behavior was clearly observed. Most cells were grown on the surface of FD-gelatin/HAp scaffolds due to the lack of the porous structure, while those were grown on the surface and inside the pore of both DCPD-gelatin/HAp microsphere scaffolds and HAp-gelatin/HAp microsphere scaffolds due to the presence of the porous structure. Thus, the porous gelatin/HAp microsphere-based scaffolds have a potential as novel bone tissue regenerative materials.