Rheological characterization of hydrogels formed by recombinantly produced spider silk

Many fibrous proteins such as spider silks exhibit impressive mechanical properties and are highly biocompatible leading to many potential biomaterial applications. For applications such as tissue engineering, polymer hydrogels have been proposed as an effective means of producing porous but stable scaffolds. Here, nanofiber-based hydrogels were produced from engineered and recombinantly produced spider silk proteins. The silk nanofibers are stable semi-flexible polymers which assemble into hydrogel networks. We studied the hydrogel rheology and determined the concentration dependence of the elastic modulus. AFM images indicate that the nanofibers might assemble into branch-like structures, which would also be consistent with the measured rheological behavior. Since the developed spider silk hydrogels are stable over weeks and show a high elastic modulus at low volume fractions, they are well suited for a broad variety of applications.