Scheme. 1 Fabrication process of the ZrO2-incorporated β-Ca2SiO4 scaffolds

Fig. 1 (A) XRD patterns of the scaffolds incorporated with different ZrO2 content sintered at 1200 ℃, (B) 15Zr-C2S scaffolds sintered at different temperature, and (C) FT-IR spectra of the β-Ca2SiO4 scaffolds incorporated with different ZrO2 content sintered at 1200 ℃.

Fig. 2 SEM images of (A) 0Zr-C2S, (B) 5Zr-C2S, (C) 10Zr-C2S and (D) 15Zr-C2S scaffolds, with SEM fracture surface images from (A3-A4) to (D3-D4)

Fig. 3 The compressive strength and porosity of the ZrO2- incorporated β-Ca2SiO4 scaffolds (n = 3; * indicated significant differences, P < 0.05)

Fig. 4 (A) pH values and (B) in vitro degradation of the ZrO2-incorporated β-Ca2SiO4 scaffolds in SBF (n = 3; *, ** and *** indicated significant differences, P < 0.05, P < 0.01 and P< 0.001), (C) FT-IR and (D) SEM images of the ZrO2- incorporated scaffold surfaces after immersed in SBF for 7 d

Fig. 5 SEM images of the attachment of rBMSCs on the ZrO2-incorporated β-Ca2SiO4 scaffolds for 1 d, (A) 0Zr-C2S; (B) 5Zr-C2S; (C) 10Zr-C2S; (D) 15Zr-C2S

Fig. 6 (A) Quantitative analysis of the proliferation of rBMSCs cultured on β-Ca2SiO4 scaffolds for 3 and 7 d (n=3); (B) ALP activity of rBMSCs cultured for 7 and 14 d on β-Ca2SiO4 scaffolds for 7 and 14 d (n = 3, * and ** indicated significant differences, P < 0.05 and 0.01)

Fig. 7 Osteogenic expression of (A) COL-1, (B) OCN, (C) RunX-2 and (D) OPN for rBMSCs cultured on β-Ca2SiO4 scaffolds by qRT-PCR analysis after 7 and 14 d (n = 3; * and ** indicated significant differences, P < 0.05 and 0.01)

Fig. 9 (A) Histological analysis with (B) quantitative analysis of newly formed bone

Fig. 8 Micro-CT evaluation of the repaired skulls at 8 weeks post-implantation