Capture of a single molecule in a nanocavity

We describe a heptameric protein pore that has been engineered to accommoda te two different cyclodextrin adapters simultaneously within the Lumen of a transmembrane beta barrel. The volume between the adapters is a cavity of similar to 4400 cubic angstroms. Analysis of single-channel recordings reve als that individual charged organic molecules can be pulled into the cavity by an electrical potential. Once trapped, an organic molecule shuttles bac k and forth between the adapters for hundreds of milliseconds. Such self-as sembling nanostructures are of interest for the fabrication of multianalyte sensors and could provide a means to control chemical reactions.