Far-from-equilibrium self-assembly is nature’s way of making actively-driven self-assembled materials such as the cytoskeleton, where the self-assembled structures are transient and collapse as the energy source driving assembly is removed. In nature, the energy these non-equilibrium systems consume can then be converted mechanical work, e.g. motion1 and continuous beating.2 Our work is aimed at using far-from-equilibrium self-assembly to creating active peptide-based materials capable of autonomous motion. We reason that the key to this are methods that improve the spatial and temporal control and speed of energy flow. We report here on our progress in this field including the design and creation of a transient programmable supramolecular peptide-gel system.3 This new transient hydrogel system uses orthogonal methods for activation and deactivation, i.e., the competition between the gelation of the oxidised cystine form of N,N’-dibenzyol-L-cystine (DBC) gelator and its reduction to the soluble cysteine by a chemical reducing agent; tri(2-carboxyethyl)phosphine (TCEP). Detailed kinetic analysis of the system allowed the authors to program the lifetime of these gels with good accuracy down to 15 min. Furthermore, we are able to generate multiple transient hydrogel cycles (sol↔gel oscillation), simply by periodically adding more of the DBC gelator to a TCEP “bath”. The general concept outlined here relies on kinetic control over self-assembly and is applicable to not only redox-active systems but other stimuli –responsive systems – which should aid the design of next-generation of spatiotemporal hydrogel peptide materials.

Transient programmable peptide self-assembly

2019 Spring National Meeting

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