Fabrication, characterization, and in vitro bioactivity evaluation of freeze-cast highly porous hardystonite ceramic reinforced by graphene oxide as a novel bone scaffold

Abstract

One of the major challenges in bone tissue engineering is the preparation of highly interconnected porous scaffolds with suitable mechanical properties. Synthetic scaffolds used in medicine are usually made of single-phase of ceramic or polymer. However, the combination of these materials with graphene-based nanofillers can produce scaffolds with improved mechanical and biological properties. In this research, we synthesize highly porous (up to 85%) and lamellar hardystonite-graphene oxide (0–1.5 wt% GO) composite scaffolds through the freeze-casting technique and then sintering it for 5 h at 1150 °C. The results of microstructural observations showed using higher amounts of GO leads to an increase in the porosity and a decrease in the shrinkage level. The optimum mechanical properties among the studied samples are related to HT-1 wt% GO (E = 71.77 ± 2.40 MPa, σ = 1.8 ± 016 MPa, and K = 47.87 MJ/m3). Therefore, biological tests were performed on the HT-1 wt% GO scaffold and HT scaffold as the optimal and control samples, respectively. In vitro bioactivity experiments confirm the formation of apatite on surfaces of HT and HT-1 wt% GO specimens after soaking them in SBF for 14 days in static circumstances. Based on the cell studies, the HT-1 wt% GO scaffold sample showed the best attachment and proliferation of osteoblastic cells. The methyl thiazole tetrazolium (MTT) assays were used to characterize the biocompatibility of the HT-1 wt% GO composites in vitro. Also, the alkaline phosphatase (ALP) activity and proliferation rate of cells on the HT-1 wt% GO composite was higher compared with the pure HT ceramics. Overall, it is concluded that the HT-1 wt% GO scaffold with enhanced biological and mechanical features is suitable for use as a novel bone scaffold.