Stretch Activated Multifunctionalization of Disulphide Linked Hydrogels

Inspired by how forces in biological tissues guide their functions <i>in-vivo</i> using mechanochemical reactions, we have developed bioinspired hydrogels where an applied tensile stretching force facilitates molecule immobilization from the surrounding environment to provide multiple avenues for functionalization. Specifically, we have developed disulfide linked polyethylene glycol hydrogels that are reinforced with a second ionically bonded sodium alginate network to simultaneously achieve stretchability and mechanochemical functionalization. To demonstrate and quantify the mechanochemical functionalization behavior, thiols produced by disulfide bond rupture were sensed during stretching using a reaction activated fluorophore dissolved in the hydrating solution. By monitoring the increase in fluorescence intensity upon stretching, it was determined that force activated molecule immobilization becomes more prominent in hydrogels with high stretchability under low stress. Such results provided guidance to design double network hydrogels that balance favorable mechanical properties and mechanochemical responsiveness. Finally, for the most mechanochemically active hydrogel, we demonstrated how the stretch-activated immobilization of a maleimide containing peptide can functionalize the gels to promote the growth of human fibroblasts. Results of this work are anticipated to encourage further research into the development of stretchable and multifunctionalizable hydrogels for biotechnology and biomedical applications.