Biologically responsive, sustainable release from metallo-drug coordinated 1D nanostructures

A multistep self-assembly process produced one-dimensional nanostructures that consisted of a monolayer membrane functionalized with a ligand that acted as a coordination site for an anticancer Pt complex. Control of the mode of the networks of intermolecular hydrogen bonds within the monolayer membrane of the nanostructures completely determined the morphologies of the one-dimensional nanostructures to be nanotapes having widths of 20-40 nm and nanotubes having widths of 16 nm (8 nm inner diameter and 4 nm membrane thickness). Various spectroscopic measurements and microscopic observations revealed that the ligand in a nanotape was located on the surface, whereas the ligand in a nanotube was selectively located on the inner surface of the nanochannel. We calculated the stability constants of the nanotape and nanotube with an anticancer Pt complex to be 10^7.81 and 10^6.53, respectively. The nanotape and nanotube were able to not only stably coordinate the anticancer Pt complex in Milli-Q water but also release it in phosphate-buffered saline through a ligand exchange reaction. With respect to sustainable, slow release of the drug, the nanotube, which has a nanochannel to store the drug, was superior to the nanotape.