Molecular self-assembly provides a powerful route for the construction of functional materials and systems with potential applications in biomedicine and nanotechnology. The �design rules� that are actively pursued in this area usually refer to thermodynamically optimised structures. It is increasingly recognised that non-equilibrium, kinetic controlled molecular assembly allows access to various superstructures with different functionalities. We will provide examples showing how such route dependant tailoring of materials properties may be achieved using biocatalytic [1], thermal and (audible) sound control of self-assembly and gelation. We will discuss supramolecular peptide nanofibers that display dynamic instability, i.e. they are formed by competing catalytically controlled assembly and dis-assembly reactions, where assembly is favoured away from equilibrium [2]. The process results in macroscopically observable temporary hydrogelation, which may be repeated upon refuelling the system with further addition of the chemically activated amino acid precursor.We demonstrate that, by varying the thermal history of a self-assembling aromatic peptide amphiphile, supramolecular chirality of nanofibers formed can be controlled, and even inverted, thereby overriding the molecular chirality of the peptidic building blocks[3,4]. This results in formation of gels with identical composition but dramatically variable nanoscale morphology, gel stiffness and proteolytic degradability. The resulting non-equilibrium nanostructures display a varying balance of aromatic and hydrogen bonding interactions which underpins the observed supramolecular helicity and fiber morphology observed. Finally, we will report on the use of audible and ultra sound to control and direct molecular self-assembly. 1. (a) S.K.M. Nalluri, et al., Chemical Science, 2013, 4, 3699-3705.; (b) Y.M. Abul-Haija, et al., Small, 2014, 10, 973�979.; (c) K. Thornton et al., Soft Matter, 2013, 9, 9430-9439. 2. S. Debnath et al., J. Am. Chem. Soc., 2013, 135, 16789�16792. 3. (a) S. Fleming, et al., Biomacromolecules, 2014, Advance Article.; (b) S. Fleming et al., Chem. Commun., 2013, 49, 10587-10589.; (c) S. Fleming et al., Langmuir, 2013, 29, 9510-9515.

(Non)-equilibrium peptide self-assembly driven by biocatalysis, temperature, and sound

248th National Meeting (2014)

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