Polypeptide Nanotoroids Formed on Substrate via Solvent Evaporation‐Induced Self‐Assembly

Abstract Nanotoroids possess unique topological structures and properties, holding great promise for applications in diverse fields. Solvent evaporation‐induced self‐assembly (SEIS) of polymers is an effective way of producing novel nanostructures on substrates, while the formation of polymer nanotoroids is rarely reported. Herein, a first example regarding the formation of well‐defined polypeptide nanotoroids on a hydrophilic substrate via SEIS is presented. On the substrates covered by a thin film of polypeptide solution, the polypeptides self‐assemble into nanorods with the evaporation of solvent. With further solvent evaporation, the solution breaks into small droplets. At the boundary of droplets, the nanorods are exposed to air, which increases their interfacial energy. As a result, these nanorods curve into nanotoroids. The size of the nanotoroids is readily adjusted in a relatively large range by initial polymer concentrations. A low affinity between the polypeptides and the substrates is essential for the nanorods curving into nanotoroids. The information gained in this work can not only enhance the understanding of both the characteristics of polymers and substrates on the SEIS behaviors, but also provide a novel route toward the construction of polymer nanotoroids on substrates.