Importance of Polyacrylamide Hydrogel Diverse Chains and Cross-Linking Density for Cell Proliferation, Aging, and Death.

Diverse chains and cross-linking density of polymers are important for cell proliferation, aging, and death. In this study, by controlling the component ratio of N,N'-methylenebisacrylamide (Bis)/acrylamide (Acr), we prepared polyacrylamide (PAM) hydrogels with three different polymer structures using ultraviolet irradiation. Moreover, we quantified their Flory's cross-linking densities, gel concentrations, and mechanical properties and evaluated their influence to HL-7702 liver cell behavior and metabolism. Results showed that PAM hydrogel at a ratio of Bis/Acr = 1:50 (Acr-50) owned the highest cross-linking density (0.04), which provided abundant binding sites for cell adhesion and allowed for rapid cell proliferation. On the basis of the binding sites, cells had strong traction interaction from fibrillate adhesion with the polymers, allowed easy cell migration, and induced the living cell aggregations with a diameter of 800 μm. Cells in aggregation exhibited healthy cell phenotypes and functions, and also the mitosis of the cells in aggregation is exactly the same with the cells in tissue. It is concluded that cell proliferation, aging, and death can be controlled by adjusting the cross-linking density and diverse chains of matrix hydrogels. This work will be helpful to design new functional soft biomaterials for tissue regeneration in the future.