Arginine clustering on calix[4]arene macrocycles for improved cell penetration and DNA delivery

Cell-penetrating peptides are widely used as molecular transporters for the internalization inside cells of various cargo, including proteins and nucleic acids. A special role is played by arginine-rich peptides and oligoarginines covalently linked or simply mixed with the cargo. Here we report cell-penetrating agents in which arginine units are clustered on a macrocyclic scaffold. Instead of using long peptides, four single arginine units were covalently attached to either the upper or lower rim of a calix[4]arene, kept in the cone conformation building a ‘parallel’ cyclic array. These new macrocyclic carriers show high efficiency in DNA delivery and transfection in a variety of cell lines.