How Does Gelation Works in VitroGel?

STAGE 1

The hydrogel formation starts with mixing the VitroGel solution with cell culture medium.  Hydrogel molecules interact with ionic molecules, such as Ca2+ or Na+, from the cell culture medium and becomes a matrix structure (hydrogel).

The process of hydrogel formation is slow when a small amount of ionic molecules is used.  At this stage, the hydrogel is soft and posses a shear-thinning and rapid recovering mechanical property, which makes the hydrogel injectable for in vivo applications. The slow hydrogel-forming process and the injectable property of the soft hydrogel create a time window for easy hydrogel transfer from the mixing tube to the cell culture plate.

STAGE 2

After soft hydrogel formation, adding 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.

The solid hydrogel possesses higher mechanical strength than the soft hydrogel.  There is a clear gel-liquid phase separation between the solid gel and top medium, which allows the medium to be changed by removing and adding medium on the top of the hydrogel.