Currently,
protein-based
hydrogels are widely applied in soft materials, tissue engineering and implantable scaffolds owing to their excellent biocompatibility, and degradability. However, most
protein-based
hydrogels are soft brittle. In this study, a ductile and mechanically enhanced
bovine serum albumin (BSA)
hydrogel is fabricated by soaking the a 1-(3-dimethylaminopropyl)-3ethylcarbodiimide hydrochloride/
N-hydroxysuccinimide (
EDC/NHS) induced BSA
hydrogel in (NH4)2SO4
solution. An
EDC/NHS coupling reaction induce
protein coupling reactions that cause the BSA skeleton to resemble architectural load-bearing walls, protecting the integrity of the
hydrogel and preventing collapse. The effects of the BSA and (NH4)2SO4 concentrations on the
hydrogel mechanics are evaluated, and the possible strengthening mechanism is discussed. Besides, the highly kosmotropic
ions greatly enhance the hydrophobic interaction within BSA
gels and
dehydration effect and their mechanical properties were significantly enhanced. The various mechanical properties of
hydrogels can be regulated over a large window by soaking
hydrogels into various
ions. And most of them can be washed away, maintaining high biocompatibility of the
protein. Importantly, the
protein hydrogels prepared by this strategy could also be modified as strain sensors. In a word, this work demonstrates a new, universal method to provide multi-functional, biocompatible, strength enhanced and regulable mechanical pure
protein hydrogel, combining the Hofmeister effect with -NH2/-COOH association groups.