Sequence−Conformation Relationship of Zwitterionic Peptide Brushes—Experiments, Theories and Simulations

Zwitterionic peptides are great candidates as antifouling coating materials in many biomedical applications. The charge distribution on the peptide is critical to the structure and properties of surface-tethered zwitterionic peptide monolayers. However, there is a lack of understanding of the relationship between the charge distribution and conformation in these systems, which is important for designing and predicting the functionality of controllable surface tethered polymer brushes. We investigated the structure and antifouling properties of surface-tethered zwitterionic peptide monolayers with different peptide chain lengths and charge distributions using a combination of surface plasma resonance, surface force, and all atomistic molecular dynamics (MD) simulation techniques. All-atom MD simulations reveal that the height of the peptide brush strongly depends on the distribution of the charges along the peptide chain. Contact map analysis reveals that the charge sequence also determines the preferred intrachain (loops and extended) and interchain (head-to-tail and parallel) structures. Through the theory developed by us, we show that the interchain electrostatic interactions are responsible for the contraction of peptide brushes with long charged blocks, while elasticity drives the contraction of peptide brushes with alternating-charged segments.