Fig. 2

BMP-2 bioactivity test under stressed conditions. a The BMP-2 was incubated in prolonged condition, 37 °C for a week, and proteolysis environment, 200 ng mL^− 1 of MMP-9 for 16 h, in the presence of Hep-MeGC. Then, it was treated with BMSCs for 4 days, and ALP staining and activity test were performed respectively to verify the bioactivity of BMP-2. N.S., Not significant. *p < 0.05, **p < 0.01, and ***p < 0.001. Scale bar is 100 μm. b Half-life extension of BMP-2 induced by Hep-MeGC. BMSCs were cultured with 100 ng mL^− 1 of BMP-2 with MeGC (blue) and Hep-MeGC (orange) for prolonged condition and with 200 ng mL^− 1 MMP-9 for proteolysis condition. The concentration of BMP-2 in culture medium were quantified by BMP-2 enzyme-linked immunosorbent assay. *p < 0.05, **p < 0.01, and ***p < 0.001 compared to PBS group