Hierarchical Helical Toroids Constructed from One-pot Controllable Self-Assembly of Polypeptides

Self-assembly has proven to be a robust strategy for constructing intricate hierarchical structures. The construction of chiral or toroidal nanostructures has attracted considerable attention. However, hierarchical nanostructures involving both chiral and toroidal features are rarely reported and related mechanism is less understood. Herein, we report a discovery of toroids with controllable helical senses from the one-pot self-assembly of polypeptides. Through the addition of selective solvent to polypeptide solution and the followed dialysis, uniform toroids with left-handed helical structures are formed. Mechanism analysis revealed that the polypeptides are initially assembled into spherical aggregates, then the spheres perforated into toroids during the dialysis process. Simultaneously, chain rearrangement occurs, resulting in an ordered packing of polypeptides within the toroids and the formation of helical structures. The formation of helical toroids can be well controlled by the assembly conditions, and its chirality was found to be dependent on the polypeptide backbone chirality. This is a pioneering example of one-pot self-assembly of hierarchical structures containing multiple topological features, providing a straightforward efficient strategy for constructing complicated nanostructures with chiral and toroidal features.