Molecules form nano containers

Researchers from the University of Minnesota and Technion-Israel Institute of Technology in Israel have found a way to coax the self-assembly of minuscule multicompartment structures.

The structures could eventually be used in drug delivery systems, according to the researchers. They would be especially appropriate for applications that require different chemicals to be delivered to the same place at the same time in precise proportions.

The key to making the compartmented structures is putting together molecules that frustrate each other. The structures are made from three highly incompatible polymer components -- a hydrocarbon, a fluorocarbon, which are hydrophobic, and polyethylene oxide, which is water-soluble.

The components are connected in the geometry of a three-armed star, and in water multiple stars self-assemble into multicompartment structures. Depending on the length of the polyethylene oxide molecule, the resulting structures are either individual nested compartments or long and worm-like with segmented cores.

The hydrocarbon and fluorocarbon components form the core of the structure so that they are protected from water by the polyethylene oxide. Units of the fluorocarbon are surrounded by the hydrocarbon, and stacks of these encapsulated units are encased in the polyethylene oxide.

The worm structures range from 12 to 20 nanometers in diameter, depending on the particular molecular structure of the three component molecules.

The nanostructures could be used in practical applications in two to five years, according to the researchers. The work appeared in the October 1, 2004 issue of Science.