Cell-adhesive hydrogels composed of peptide nanofibers responsive to biological ions

Novel calcium ion (Ca2+)-responsive hydrogels composed of designed beta-sheet peptides were constructed. As the novel designed peptide, E1Y9, has a Glu residue to interact with Ca2+, the peptide in the sol-state self-assembled into hydrogels in the presence of Ca2+. The hydrogelation did not occur in the absence of Ca2+; therefore, Ca2+-dependent hydrogelation was achieved by the molecular design. The hydrogelation from the viscous sol-state solution can be induced by a slower self-assembly process of the b-sheet peptide involving a rapid process of Ca(2+)binding. When the sol-state peptide solution was injected with Ca2+, gel drops and strings with desired shapes could be constructed. Different cell lines can be cultured on the hydrogel, demonstrating its low toxicity, which is comparable to commercially available microtiter plate surfaces for cell culture. Furthermore, the hydrogels showed a high cell-adhesive ability that was similar in magnitude to fibronectin, which is a native cell-adhesive protein. The Ca2+-responsive peptide nanofiber-based hydrogelation system will facilitate novel studies exploiting self-assembling peptide nanomaterials that will lead to cell-based technology, such as three-dimensional cell culturing. Polymer Journal (2012) 44, 651-657; doi: 10.1038/pj.2012.48; published online 4 April 2012