In one aspect, the invention relates to a peptide that forms a calcium-dependent hydrogel using a rationally engineered beta roll peptide. In the absence of calcium, the peptide is intrinsically disordered. Upon addition of calcium, the peptide forms a corkscrew-like structure. In one embodiment, one face of the beta roll is mutated to comprise leucine residues. In some embodiments, a leucine zipper forming helical domain to the engineered beta roll forms hydrogels by physical cross-linking in calcium rich environments.