Formation of Nanotubes By Catanionic Mixtures of Drug-Amphiphiles

Self-assembly of therapeutic agents into well-defined architectures not only creates a new means for the development of self-delivering anticancer drugs or molecular probes, but the self-assembly process itself also provides new insight for the rational design of micro- or nanostructures with increased complexity. Tubular structures, in particular, have drawn much research interest in various biomedical and electronical areas, owing to new properties associated with their hollow nature. There is a great deal of literature that reports the co-assembly of oppositely charged amphiphilic molecules into bilayer-based structures, such as vesicles, icosahedra, nanodiscs, nanobelts, and nanotubes. It is generally believed that the formation of ion pairs by oppositely charge surfactants alters the packing geometry as a result of charge screening. In this context, we report our use of catanionic mixtures (CAMs) of drug amphiphiles containing a 36% fixed drug loading to construct tubular structures. We attempted to elucidate the potential factors that contribute to the construction of such interesting tubular morphologies.