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Abstract Surface-grafted elastin has found a wide range of uses such as sensing, tissue engineering and capture/release applications because of its ability to undergo stimuli-responsive phase transition. While various methods exist to control surface grafting in general, it is still difficult to control orientation as attachment occurs. This study investigates using an electric field as a new approach to control the surface-grafting of short elastin-like polypeptide (ELP). Characterization of ELP grafting to gold via quartz crystal microbalance with dissipation, atomic force microscopy and temperature ramping experiments revealed that the charge/hydrophobicity of the peptides, rearrangement kinetics and an applied electric field impacted the grafted morphology of ELP. Specifically, an ELP with a negative charge on the opposite end of the surface-binding moiety assembled in a more upright orientation, and a sufficient electric field pushed the charge away from the surface compared to when the same peptide was assembled in no electric field. In addition, this study demonstrated that assembling charged ELP in an applied electric field impacts transition behavior. Overall, this study reveals new strategies for achieving desirable and predictable surface properties of surface-bound ELP. 

Control of ionomer thin films on metal surfaces is important for a range of electrodes used in electrochemical applications. Engineered peptides have emerged as powerful tools in electrode assembly because binding sites and peptide structures can be modulated by changing the amino acid sequence. However, no studies have been conducted showing peptides can be engineered to interact with ionomers and metals simultaneously. In this study, we design a single-repeat elastin-like peptide to bind to gold using a cysteine residue, and bind to a perfluorinated sulfonic-acid ionomer called Nafion® using a lysine guest residue. Quartz crystal microbalance with dissipation monitoring and atomic force microscopy are used to show that an elastin-like peptide monolayer attached to gold facilitates the formation of a thin, phase-separated ionomer layer. Dynamic light scattering confirms that the interaction between the peptide with the lysine residue and the ionomer also happens in solution, and circular dichroism shows that the peptides maintain their secondary structures in the presence of ionomer. These results demonstrate that elastin-like peptides are promising tools for ionomer control in electrode engineering.