Fig. 3

A Surface and cross-sectional microstructure of cross-linked hydrogels. Scale bars are 10 µm and 5 µm, respectively. B Twenty-one-day incubation of human osteoblasts displayed attachment and morphological adaptation. (Yellow arrows: cells). C Bright-field imaging revealed an almost uniform size of microspheres in three groups cross-linked using Ca, Ba and Sr. Scale bars for days 0 and 21 are 100 µm and 200 µm, respectively. Tumefy areas on the periphery of all microsphere types are associated with the cell motility and growth of encapsulated cells. D, E Cell viability and proliferation of human osteoblast-like MG-63 cells were monitored using Calcein- AM staining and MTT assay after 21 days of microencapsulation. (Live cells: green and nuclei: blue). Significance is indicated (* p < 0.05)