Self-Sorting in Diastereomeric Mixtures of Functionalized Dipeptides

Abstract

Self-sorting in functionalized dipeptide systems can be driven by the chirality of a single amino acid, both at a high pH in the micellar state and at a low pH in the gel state. The structures formed are affected to some degree by the relative concentrations of each component showing the complexity of such an approach. The structures underpinning the gel network are predefined by the micellar structures at a high pH. Here, we describe the systems prepared from two dipeptide-based gelators that differ only by the chirality of one of the amino acids. We provide firm evidence for self-sorting in the micellar and gel phases using small-angle neutron scattering and cryo-transmission electron microscopy (cryo-TEM), showing that complete self-sorting occurs across a range of relative concentrations.

Self-Sorting vs Coassembly in Peptide Amphiphile Supramolecular Nanostructures

“…Chirality is one of the many factors that govern the formation of helical and fibrillar nanostructures. − While manipulating molecular chirality has been explored for self-sorted artificial systems, the role of supramolecular chirality in the creation of nanostructures with more than one type of molecule needs to be established. This is an area that is also very relevant to the amplification of chirality from nanostructures to hierarchical assemblies. ,, Self-sorting can be controlled by manipulating intermolecular hydrogen-bonding sites, , or combining molecules with distinct geometric shapes to increase the enthalpic penalty of mixing. , For instance, self-sorting supramolecular hydrogels have been developed where one component assembles due to peptide-type hydrogen bonding, while the other assembles due to lipid-type hydrophobic collapse, with each component responding to an independent chemical or enzymatic stimulus to form a supramolecular double network (SDN). , However, self-sorting networks from geometrically and chemically similar components have been more challenging to create, although recent progress in thermodynamic and kinetic control of self-assembly has provided insight into self-sorting strategies in supramolecular copolymerization. ,,, …”