ABSTRACT

A key challenge in peptide self-assembly is the design of appropriate molecular building blocks that can undergo spontaneous organization into well-defined and stable nanoscale structures using noncovalent bonds. These noncovalent bonds typically include hydrogen bonds, electrostatic interactions, stacking interactions, hydrophobic interactions, and van der Waals interactions. Although all of these forces individually are rather weak, their collective efforts can yield highly stable assemblies. Over the past decade, a broad range of peptidic molecules has been developed to create self-assembling nanotubes, varying from peptide amphiphiles (PAs), cyclic peptides, to amyloid-related peptide elements. 15.2.1 Peptide Amphiphile NanotubesOver the past decade the self-assembly of PAs has been of increasing interest for a variety of biological applications [17-20]. PAs consist of a hydrophilic head attached to a hydrophobic tail and self-assemble through hydrophobic/hydrophilic interactions in such a way that in aqueous environments the alkyl tails pack in the centre of and the head groups orient to the outer surface of the nanotubes (Figs. 15.1A and 15.2A) [21]. The experimental conditions to form nanotubes from

Figure 15.1 Schematic representation (left) and examples of chemical structures (right) of various peptide building blocks that undergo self-assembly.