A nanostructure composed of a plurality of peptides, each peptide containing at least one aromatic amino acid, whereby one or more of these peptides is end-capping modified, is disclosed. The nanostructure can take a tubular, fibrillar, planar or spherical shape, and can encapsulate, entrap or be coated by other materials. Methods of preparing the nanostructure, and devices and methods utilizing same are also disclosed.