(552d) Thermodynamic Properties of Antifouling Polyproline II Helix Peptide Monolayers on Gold

Polyproline II (PPII) helix peptides are promising materials because of their antifouling properties. However, little is understood about the mechanisms of their assembly and antifouling properties. Here, we study PPII peptide assembly and antifouling thermodynamics to uncover the drivers behind PPII properties. A quartz crystal microbalance with dissipation (QCM-D) is used to track mass change with time on a gold surface while an absorption and rearrangement kinetic model is fit to the data at 18-40°C. We confirm the kinetic mechanism is a two-step process, with significant rearrangement, and an insignificant backward reaction rate to the initially adsorbed state. By using the Van't Hoff and Eyring equations, we found the thermodynamic properties of the initial absorption step and the rearrangement, which indicates that entropy plays a key role in the process. The thermodynamic mechanisms of antifouling are similarly explored. These results will be used to improve the design of PPII peptides, where hydrophobicity is likely a key parameter impacting the formation and properties of these promising materials.