VitroGel solution is room temperature stable and free-flowing. The hydrogel gelation/formation starts by mixing the VitroGel solution with the cell culture medium. Hydrogel molecules interact with ionic molecules such as Ca2+ and Na+ from the cell culture medium and form the matrix structure (hydrogel).
The process of hydrogel formation is slow when a small amount of ionic molecules are used. At this stage, the hydrogel is soft and possesses a shear-thinning and rapid recovering mechanical property, which makes the hydrogel easy to transfer to a culture plate or use for injection.
After soft hydrogel formation, adding an additional cell culture medium on top of the hydrogel would allow more ionic molecules to penetrate into the hydrogel matrix and further saturate the hydrogel cross-linking. A solid hydrogel would form during this process.