Functional Polyion Complex Vesicles Enabled by Supramolecular Reversible Coordination Polyelectrolytes

Reported here is a new class of PICsomes (vesicles formed by polyelectrolyte complexation) in which the anionic/neutral diblock copolymer is replaced by an anionic, reversible, supramolecular polyelectrolyte based on metal–ligand coordination. This supramolecular polyelectrolyte forms exclusively inside the wall of the assembly, and therefore self‐adjusts its length to that of the cationic block provided. Moreover, the supramolecular coordination polyelectrolytes introduce new and tunable properties and functions associated with the specific metal. As a proof‐of‐concept Mn‐based PICsomes were prepared and display high magnetic relaxivity, as well as enhanced contrast in in vitro magnetic resonance imaging tests. The simplicity of our approach, together with the new functions derived from the metal ions, demonstrates a robust strategy for the preparation of a variety of PICsomes with well‐defined and tunable structures and properties.