Nonswelling Click-Cross-Linked Gelatin and PEG Hydrogels with Tunable Properties Using Pluronic Linkers

Swelling of hydrogels leads to a decrease in mechanical performance coupled with complications in solute diffusion. In addition, hydrogel swelling affects patient safety in biomedical applications such as compression of tissue and fluid blockage. A conventional strategy for suppressing swelling is to introduce a thermoresponsive polymer with a lower critical solution temperature (LCST) within the network structure to counter the water uptake at elevated temperature. However, altering the gel's mechanical strength via modification of the network structure often affects the water uptake behavior and thus a nonswelling platform with tunable mechanical properties suitable for various biomedical applications is desirable. In this study we applied the commercially available triblock PEG-PPG-PEG (Pluronic) as a cross-linker for the preparation of nucleophilic thiol-yne click cross-linked hydrogels with suppressed swelling at physiologically relevant temperature. The mechanical properties and degradation rate of these nonswelling hydrogels can be tuned by judicious combinations of the available linkers. The Pluronic linkers can be applied to prepare biologically relevant gelatin based hydrogels with suppressed swelling under physiological conditions that support attachment of fibroblast cells in 2D culture and controlled release of albumin, paving the way for the development of reliable and better performing soft biomaterials.