Adding to the rapidly growing list of developments in the nascent field of nanotechnology, researchers have created self-assembling molecules that link together to form tiny rosette-shaped tubes (see image). According to the scientists, these novel nanotubes can serve as scaffolds for various molecular add-ons aimed at giving the structures particular properties. As such, they could form the basis for molecular wires and other components of nanoscale electronic devices, as well as drug delivery systems. A report detailing the findings appears today in the early online edition of the Proceedings of the National Academy of Sciences.

During the self-assembly process, say Purdue University chemist Hicham Fenniri and his colleagues, the molecules organize themselves into groups of six to form diminutive rings, which then join together to make the tubes. Electrical charges on the outside of each tube form an electrostatic belt, onto which other molecules can be attached. "By using different chemicals on the outside of the structure, you can modify its function or make it bind to a specific target, such as amino acid," Fenniri explains. "It's like we have a skeleton, and we just have to put a dress on it. And we can decorate the tube with all sorts of dresses."

Remarkably, the rosette nanotubes flourish in the face of heat. "This opposes common wisdom, because generally when you heat something it falls apart," Fenniri observes. "Our demonstrations show that these structures become more and more stable under the influence of temperature and attain a new level of self-organization." Thus, he says, they could aid the development of nanoscale biomedical devices for use inside the human body.