Unsaturation-Dependent Nanostructures Self-Assembled from Oligopeptide Amphiphiles Capable of Generating Singlet Oxygen

We report here on three oligopeptide amphiphiles (OPA1-3) with different unsaturated double bonds, which self-assemble into shape-specific nanostructures. It was found that OPA1 with saturated hydrophobic tail self-assembled into conventional cylindrical nanofibers, while the unsaturated OPA2-3 molecules self-organized into helical nanoarchitectures. Due to the different double bond numbers in hydrophobic tails of OPA2-3, the helical pitch and width of their self-assemblies varied. Specially, linoleic acid-bearing OPA3 could be oxidized by lipoxidase to create hydroperoxide-containing OPA4, which further generated singlet oxygen (O-1(2)) in the presence of catalytic iron (II) ion. The established system may provide a self-deliverable nanoplatform for O-1(2)-mediated cancer treatment.