Bio-Inspired Peptide Membranes for CO ₂ Capture: A Molecular Dynamics Study of A ₆ H and A ₆ R Interfaces

The increasing concentration of atmospheric CO₂ demands the development of advanced and sustainable materials for carbon capture. Peptide-based nanostructures have emerged as promising candidates due to their tunable chemistry, biocompatibility, and ability to self-assemble into ordered supramolecular architectures. In this work, we investigate the adsorption behavior of CO₂ on self-assembled A₆H and A₆R peptide membranes through classical molecular dynamics simulations. The A₆H and A₆R sequences consist of six alanine residues capped by a terminal histidine or arginine residue, respectively, and self-assemble into stable β-sheet membrane structures whose surface charge distribution and hydration organization are governed by the nature of the terminal residue. After equilibrating the membranes in an aqueous medium, water molecules were removed, and CO₂ was introduced into the simulation box to evaluate gas-surface interactions under idealized gas-phase contact conditions. The results reveal distinct adsorption mechanisms governed by headgroup chemistry: the imidazole-terminated A₆H interface exhibits preferential electrostatic and hydrogen-bond-driven interactions with CO₂, whereas the guanidinium-terminated A₆R membrane, characterized by a higher surface charge density, promotes enhanced electrostatic attraction and a larger number of CO₂ binding events. These findings highlight how the chemistry of peptide terminal residues modulates CO₂ affinity at ordered, self-assembled membrane interfaces, underscoring the potential of bioinspired peptide membranes as tunable platforms for carbon capture. By focusing on experimentally validated supramolecular architectures rather than peptide aggregates or hybrid systems, this study provides molecular-level insights that can inform the rational design of peptide-based sorbent materials for sustainable CO₂ sequestration.