Thin peptide hydrogel membranes suitable as scaffolds for engineering layered biostructures

Abstract

A short tetramer peptide, Ac-IVKC, spontaneously formed a hydrogel in water. Disulfide bonds were introduced via hydrogen peroxide (H₂O₂)-assisted oxidation, resulting in (Ac-IVKC)₂ dimers. The extent of disulfide bond formation and gel stiffness increased with the amount of H₂O₂ used and 100% dimerization was achieved with 0.2% H₂O₂. The resultant gel achieved an elastic modulus of ∼0.9 MPa, which to our knowledge, has not been reported for peptide-based hydrogels. The enhanced mechanical property enabled the fabrication of thin and transparent membranes. The hydrogel could also be handled with forceps at mm thickness, greatly increasing its ease of physical manipulation. Excess H₂O₂ was removed and the membrane was then infused with cell culture media. Various cells, including primary human corneal stromal and epithelial cells, were seeded onto the hydrogel membrane and demonstrated to remain viable. Depending on the intended application, specific cell combination or membrane stacking order could be used to engineer layered biostructures. STATEMENT OF SIGNIFICANCE: A short tetramer peptide - Ac-IVKC - spontaneously formed a hydrogel in water and disulfide bonds were introduced via hydrogen peroxide (H₂O₂)-assisted oxidation. The extent of disulfide-bond formation and gel stiffness were modulated by the amount of H₂O₂. At maximum disulfide-bond formation, the hydrogel achieved an elastic modulus of ∼0.9 MPa, which to our knowledge, has not been reported for peptide-based hydrogels. The enhanced mechanical property enabled the fabrication of thin transparent membranes that can be physically manipulated at mm thickness. The gels also supported 3D cell growth, including primary human corneal stromal and epithelial cells. Depending on the intended application, specific combination of cells or individual membrane stacking order could be used to engineer layered biostructures.

Keywords: Disulfide bonds; Layered biostructures; Membranes; Scaffolds; Tissue engineering; Ultrashort peptide hydrogel.