The mechanical properties of hydrogels have a profound effect on cellular responses in tissue engineering applications. In this study, poly(ethylene glycol)-keratin (PEG-KRTN) hydrogels with tunable mechanical properties were prepared by varying molar mass of the maleimide functionalized PEG in the thiol-maleimide chemistry. Reduced keratins were reacted with PEG-maleimides having 2000 Da and 6000 Da molar masses. Viscoelastic and physiochemical properties and cytocompatibility of these hydrogels were tested. Storage modulus values were obtained as 2613 ± 254 Pa and 1313 ± 345 Pa for PEG2000-KRTN and PEG6000-KRTN hydrogels, respectively. Strain sweep data indicate that the linear viscoelastic region (LVER) of the PEG6000-KRTN hydrogel spans up to 40% strain value, whereas it is limited to 10% critical strain for the PEG2000-KRTN hydrogel. PEG6000-KRTN hydrogel presented higher swelling ratios and porosity. CCK-8 test showed that both hydrogels promoted the proliferation of L929 mouse fibroblast cells and, hence, can be applied in soft tissue engineering.

Keywords: keratin, poly(ethylene glycol), michael addition reaction, hydrogel, rheology.