Self-assembly of multidomain peptides: sequence variation allows control over cross-linking and viscoelasticity.

An important goal in supramolecular chemistry is to achieve controlled self-assembly of molecules into well-defined nanostructures and the subsequent control over macroscopic properties resulting from the formation of a nanostructured material. Particularly important to our lab is control over viscoelasticity and bioactivity. Recently we described a multidomain peptide motif that can self-assemble into nanofibers 2 x 6 x 120 nm. In this work we describe how sequence variations in this general motif can be used to create nanofibrous gels that have storage moduli, which range over 2 orders of magnitude and can undergo shear thinning and shear recovery while at the modest concentration of 1% by weight. Gel formation is controlled by addition of oppositely charged multivalent ions such as phosphate and magnesium and can be carried out at physiological pH. We also demonstrate how maximum strength can be obtained via covalent capture of the nanofibers through disulfide bond formation. Together these hydrogel properties are ideally suited as injectable materials for drug and cell delivery.