Programming the π-Conjugated Peptide Morphology by Controlling Molecular Sequence: A Molecular Dynamics Simulation Study

Biohybrid amphiphiles offer a versatile platform for programming material structures and functionalities across hierarchical length scales. While significant progress have been made with respect to control their self-assembly process, the challenge lies in exploring the vast parameter space available for experimental synthesis. In this study, coarse-grained model is employed to investigate the morphology formation of π-conjugated peptides by using molecular dynamics simulations. The conjugated core can stack onto each other due to π-π interactions, and symmetric peptide groups are placed at two sides of the core. We examined the conjugated core length (N_c) and peptide length (N_p) effects on the system morphology. Our findings show that systems with small N_c and N_p exhibit clear, fiber-like structures. As N_c increases with a short N_p, the morphology expands in all directions, leading to network-like structures. Conversely, when N_p significantly exceeds N_c, peptide steric interactions restrict structural growth, resulting in disordered morphologies. To explain these observations, we developed a theoretical framework that captures the competition between peptide steric interactions and conjugated core stacking, aligning well with our simulation results. This study underscores the critical role of molecular sequence in programming the morphology of π-conjugated peptide systems.