Time-Resolved Dynamic Assembly and Disassembly of Fueled Peptide Systems

Many molecules can self-assemble into higher order structures. Depending on the environment, the molecules will either assemble or disassemble towards their equilibrium (lowest) free energy state. Fueled molecular systems allow for a fundamentally di!erent behavior, namely an assembly into a higher free energy state (via the consumption of fuel) and a subsequent disassembly, allowing for new material properties. Here we quantify the fueled assembly and disassembly for structures formed by Lphenylalanine acyl ethyl phosphate (FEPs) and contrast this with the equilibrium self-assembly of diphenylalanine (F2). Importantly, we derive kinetic and thermodynamic parameters, e.g., e!ective (dis)assembly rates, phase coexistence points, and chemical potential biases for this system by fitting a mean-field model for chemical fueling of transient states (CFTS) to time-resolved atomic force microscopy (AFM) data. This quantitative framework provides a physical basis to define and analyze the lifetime of transient states, establishing how initial fuel concentrations and internal thermodynamic parameters dictate such non-equilibrium systems. Additional ex-situ AFM experiments yield molecular structural information and delineate the influence of substrates. Understanding the underlying mechanisms for fueled molecular systems is essential for further developing this growing field.