Design of Hydrolytically Degradable Polyethylene Glycol Crosslinkers for Facile Control of Hydrogel Degradation

Hydrogels, whose degradability can be controlled while also preserving cell viability or biomolecule stability, are in demand. Degradable polyethylene glycol crosslinkers are hydrolytically designed for use in hydrogels. Degradation is controlled by crosslinker chemical structure, such as introducing local hydrophobicity, steric hindrance, or electron-withdrawing moieties near a degradable ester moiety. Hydrogels made using these crosslinkers have gelation times from 1 to 22 min, storage moduli from 3 to 10 kPa, mesh sizes from 10 to 13 nm, and degradation times from 18 h to 16 d. However, when reaction conditions are modified to achieve similar gelation time, hydrogels have similar initial properties but preserve the wide range of degradation times. All crosslinkers support high cell viability upon hydrogel encapsulation or exposure to leachables and degradation products. This innovation in controlling degradation can help realize the hydrogels' potential for drug delivery or as matrices for cell encapsulation and transplantation.