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.

Cerium oxide/hydroxide adsorbents have emerged as promising phosphate removal materials due to their excellent performance and stability. In this study, an engineered cerium affinity peptide immobilized on a metal surface was utilized to synthesize a novel, nanoscale, and bio-enabled phosphate adsorbent. The goal of this work was to characterize the binding of phosphate and potential competing ions to the novel material, demonstrating the potential utility of the engineered peptide in biotemplating applications. Phosphate binding and competing ion binding with time were investigated via a quartz crystal microbalance with dissipation (QCM-D). Kinetic modeling of the QCM-D data revealed that the bio-enabled material facilitated strong phosphate adsorption behavior in a wide pH range of 3–7. Changing the media from simple phosphate solutions to more complex synthetic wastewater solutions did not negatively impact the observed binding constants. The main phosphate adsorption mechanism likely followed a ligand exchange process, with enhanced adsorption achieved by increasing the number of surficial hydroxide groups. The strong binding behavior observed with phosphate was not observed when the material was exposed to common competing ions. Overall, this study presents a sequence-defined peptide as a promising tool for the engineering of advanced phosphate capture materials.

Cerium has a wide range of current and emerging applications, and the binding of cerium ions to solid substrates is important for cerium recovery, or in advanced material synthesis. In this study, we investigate the affinity of a surface‐bound peptide derived from the EF‐hand loop I of calmodulin for cerium (III) ions and compare the results to a scrambled control. Results obtained via quartz crystal microbalance with dissipation are used to estimate the dissociation constant between the bound EF‐hand loop I peptide and cerium (III) ions (1.3 ± 0.1 μM), which is comparable with other dissociation constants measured for EF‐hand peptides and cerium ions in solution reported this work and in literature (0.95‐5.8 μM). Circular dichroism also suggests that the peptide binds to cerium (III) ions in solution, and undergoes a secondary structural change upon binding. Overall, this study shows that EF‐hand loop peptides are capable of binding cerium (III) ions in solution and when attached to a solid substrate.

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A high-throughput platform was developed to analyze struvite formation, finding that peptide addition modulates growth in a potentially favorable way.