Tuning the mechanical properties of alginate-peptide hydrogels

Alginate, a polysaccharide that gels in the presence of divalent ions, has been used in the field of regenerative medicine to facilitate cell growth in impaired tissues by providing an artificial bio-surrounding similar to the natural extra cellular matrix (ECM). Here, we present a systematic investigation of the effect of three arginine-glycine-aspartic acid (RGD)-containing peptides, G₆KRGDY, A₆KRGDY and V₆KRGDY, on the physical properties of alginate-peptide hydrogels. Rheology measurements showed that the storage modulus of the alginate-A₆KRGDY and alginate-V₆KRGDY gels is an order of magnitude higher than that of the alginate-G₆KRGDY gel. Small angle X-ray scattering (SAXS) measurements suggest that the difference in the mechanical properties of the gels is due to the formation of larger peptide junction zones in addition to the ones formed by calcium ions. These findings indicate that the peptides' ability to self-assemble in aqueous solution is a significant factor in tuning the stiffness of the alginate/peptide hybrid hydrogels.