Tuning the stiffness of surfaces by assembling genetically engineered polypeptides with tailored amino acid sequence

We introduce elastin-like recombinamers (ELRs) as polypeptides with precise amino acid positioning to generate polypeptide coatings with tunable rigidity. Two ELRs are used: V84-ELR, a hydrophobic monoblock, and EI-ELR, an amphiphilic diblock. Both were modified with the amine-reactive tetrakis (hydroxymethyl) phosphonium chloride compound. We evaluated the affinity, the conformation, and the dissipative behavior of ELRs assembled on alkanethiol self-assembled coatings by quartz crystal microbalance with dissipation monitoring, multi-parametric surface plasmon resonance, and atomic force microscopy. The thickness of the polypeptide coatings showcase the preferential affinity of ELRs to NH2 and CH3 terminated surfaces. We demonstrate that V84-ELR strongly bonded to the substrate and reorganizes into an extended and more hydrated layer as the adsorbed amount increases, whereas EI-ELR has a less dissipative behavior. The results suggest that ELR adsorption depends on the amino acid sequence and the substrate chemistry, ultimately influencing the stiffness of the polypeptide coatings.