Evaluation of the biocompatibility of the organic-inorganic, double-bonded hydrogels in vitro. A-B) Live/dead staining of BMMs and MC3T3-E1 cells on different hydrogels after 3 days' co-culture. C-D) CCK-8 assay of BMMs and MC3T3-E1 cells. (n = 3, all values were mean ± std. dev., NS, not significant, *p < 0.05, **p < 0.01 when comparing A-H + AB-O and other groups via two-way ANOVA analysis followed by Tukey's multiple comparison test by GraphPad Prism 7.0 Software (USA)).