Figure 3. α-CDYRGDS-PEG hydrogels with independently tunable mechanical and cell adhesion properties.

An array of hydrogels was synthesized with independently varied cross-linking densities (% of PEGDA, necklace) and cell adhesions (α-CD-YRGDS, nanobeads). a, The shear storage moduli of the hydrogels varied only with the crosslinking density and did not change with the incorporation of α-CD nanobeads. The PEGDA 15% (w/v) hydrogels with shear storage modulus ~30 kPa are defined as stiff substrates, while PEGDA 10% (w/v) with shear storage modulus ~7–10 kPa as moderately stiff, and PEGDA 5% (w/v) with shear storage modulus ~0.5 kPa as soft substrates. b, The amount of water absorbed into the hydrogels (swelling ratio) also varied with respect to the crosslinking density, and it did not change with α-CD nanobeads. c, MSCs cultured on the surfaces of stiff and soft hydrogels with varying concentrations of cell adhesive nanobeads have different morphological and organization characteristics (F-actin staining with Texas Red^®-X phalloidin at 16 h). Cells were able to spread on the soft surfaces and aggregated with increasing adhesion compared to cells seeded on the stiffer substrates that had longer cell extensions in isolation (little aggregation). Data collected throughout the study of compression modulus and swelling ratio are presented as a mean ± standard deviation of three or more data samples (*p ≤ 0.05).