Fig. 1.

A) Dynamic swelling behaviors and B) In vitro degradation behaviors of GelMA-NanoclayX hydrogels in deionized water. C) Compressive stress–strain curves of the GelMA-NanoclayX hydrogels. D) The effect of the bioink concentration on the mechanical strength. E-F) In vitro metformin release profile from metformin-loaded GelMA-Nanoclay8% as a function of time. G) Proliferation of BMSCs in culture medium with different metformin concentrations (1 μg/mL, 2 μg/mL and 3 μg/mL) on days 1, 4, and 7. H-J) Expression of OCN, VEGF, and TNF-α mRNA in BMSCs in normal or high-glucose medium after 72 h. K-L) The schematic diagram and scanning electron microscopy (SEM) images of the 3D-printed hydrogel scaffolds, along with the energy dispersive spectroscopy (EDS) analysis. (scale bar: thick bar = 2.5 mm, thin bar = 250 μm). (Statistical analysis of the hydrogel ultimate strength data was conducted, and all the results are presented as means ± SD, *p < 0.05, **p < 0.01).