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

Graphical Oligopeptide amphiphiles (OPAs) with different degrees of unsaturation self-assemble into shape-specific nanostructures. The linoleic acid-bearing OPA could generate singlet oxygen ( 1 O 2 ) in the presence of lipoxidase and catalytic iron (II) ion, which offers new insight into designing self-deliverable nanoplatform for 1 O 2 -mediated cancer treatment. 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 ( 1 O 2 ) in the presence of catalytic iron (II) ion. The established system may provide a self-deliverable nanoplatform for 1 O 2 -mediated cancer treatment.