Dynamic heterodimer-functionalized surfaces for endothelial cell adhesion

The functionalization of hydrogels for receptor-mediated cell adhesion is one approach for targeted cell and tissue engineering applications. In this study, polyacrylamide gel surfaces were functionalized with specific cell adhesion ligands via the self-assembly of a peptide-based heterodimer. The system was comprised of a cysteine-terminated monomer, A (MW ∼ 5400), grafted to the polyacrylamide gels and a complementary ligand presenting monomer, BX (MW ∼ 5800) that was designed to heterodimerize with A. Two ligand presenting monomers were synthesized: one presenting the RGDS ligand, BD, for receptor-mediated cell adhesion, and the other, a control monomer presenting the nonadhesive RGES ligand, BE. Assembly of the peptide pair A–BX by association of the monomers into a coiled coil was verified by circular dichroism in solution. Binding studies were conducted to determine the dissociation constant of the pair A–BX, which was found to be KD∼10-8KD∼10-8 m. Polyacrylamide gels functionalized with A–BX heterodimers were evaluated for cell adhesion using bovine aortic endothelial cells (BAECs). Endothelial cells cultured on the A–BD functionalized surfaces demonstrated typical cell morphologies and expected spreading behavior as a function of the density of RGDS ligand, calculated as the amount of BD associated with grafted A on the surface of the gels. In contrast, A–BE linked surfaces supported no cell adhesion. The adhesion of the substrate was dynamically altered through the reassembly of A–BX dimers as BD molecules in the solution replaced BE molecules at the substrate. The molecular constructs described here demonstrate the potential to design a broad family of switchable peptides that impart the dynamic control of biofunctionality at an interface, which would be useful for precise manipulation of cell physiology.