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, B X (MW ∼ 5800) that was designed to heterodimerize with A. Two ligand presenting monomers were synthesized: one presenting the RGDS ligand, B D, for receptor-mediated cell adhesion, and the other, a control monomer presenting the nonadhesive RGES ligand, B E. Assembly of the peptide pair A–B X 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–B X, which was found to be K D ∼ 1 0 - 8 m. Polyacrylamide gels functionalized with A–B X heterodimers were evaluated for cell adhesion using bovine aortic endothelial cells (BAECs). Endothelial cells cultured on the A–B D functionalized surfaces demonstrated typical cell morphologies and expected spreading behavior as a function of the density of RGDS ligand, calculated as the amount of B D associated with grafted A on the surface of the gels. In contrast, A–B E linked surfaces supported no cell adhesion. The adhesion of the substrate was dynamically altered through the reassembly of A–B X dimers as B D molecules in the solution replaced B E 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.