Gelatin methacrylate (GelMA) hydrogels are a promising material for use in a variety of tissue engineering applications. Herein, we focused on identifying the optimal irradiation time necessary to photopolymerize GelMA hydrogels with visible blue light in a manner that did not adversely
impact the biophysical properties of these cell-containing gels. We assessed the toxic effects of different irradiation times (3, 5, 10, 20 and 40 seconds) on BMMSCs encapsulated in a GelMA hydrogel using lithium phenyl-2,4,6 trimethylbenzoylphosphinate (LAP) as a photoinitiator. Both CCK-8
assays and Live-Dead staining were used to measure BMMSCs viability. We observed increasing compression strength as a function of increased irradiation time, although this corresponded to a reduction in swelling ratio and pore sizes. We ultimately found that when using LAP as a photoinitiator,
the optimal irradiation time was 5–10 seconds, which was suitable for bone tissue engineering application. Ultimately we determined that a 5 second irradiation time was optimal for studies of encapsulated stem cells.