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In this study, a novel scaffold fabrication method was developed by combining microwave irradiation and gas foaming. Chitosan superporous hydrogels (SPHs) and chitosan-hydroxyapatite (HA) superporous hydrogel composites (SPHCs) were prepared by using this method in the presence of crosslinking agent, glyoxal, and a gas-blowing agent, NaHCO3. In order to examine the effect of HA on composite structure and cellular behaviour, two types of HA particles, i.e. spherical beads in 45-80 µm diameter and powder form, were used. While rapid heating with microwave irradiation enhances gas blowing, pH increment, which is accelerated by NaHCO3 decomposition, provides better crosslinking. Thus, interconnected and well-established macroporous hydrogels/hydrogel composites were produced easily and rapidly (~1 min). Cell culture studies, which were carried out under static and dynamic conditions with MC3T3-E1 pre-osteoblastic cells, indicated that chitosan-HA bead SPHCs supported cellular proliferation and osteoblastic differentiation better than chitosan SPHs and chitosan-HA powder SPHCs. In conclusion, simultaneous gas foaming and microwave crosslinking can be evaluated for the preparation of composite scaffolds which have superior properties for bone tissue engineering.

In this study, polycaprolactone (PCL) scaffolds, consisting of agglomerated microspheres with nanotopographic surface structures, were fabricated by the freeze-drying method. These scaffolds were coated with bone-like apatite by using a calcium phosphate solution similar to saturated simulated body fluid (10× SBF-like) in two different immersion periods (6 and 24 h). Scanning electron microscopic views of the 6-h treatment in 10× SBF-like solution showed formation of calcium phosphate nucleation sites on the PCL scaffolds, while the apatite particles formed characteristic cauliflower-like morphology after 24 h. The X-ray diffraction (XRD) data showed that the mineral phase was made of hydroxyapatite (HA). The osteogenic activity of untreated and SBF-treated PCL scaffolds was examined by pre-osteoblastic MC3T3 cell culture studies. Cells had attached and spread on both the PCL scaffolds and the 6-h SBF immersion-treated scaffolds.

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