Artificial cilia: Scientists develop nano-structured transportation system

Molecules that wiggle when exposed to light are known for a long time. But directed movement had not been possible up until now because back and forth movement cancel each other. To achieve a net displacement, the cilia should beat only to one side. Applying a trick within the molecular construction, the chemists of Kiel University's Collaborative Research Centre 677 "Function by Switching" solved this problem: Moreover, to get those molecular cilia up and running, the scientists fixed them on a surface. "We attached a kind of molecular suction cup onto the switches," project leader Herges explains.

Studies have shown that this suction cup adheres very well to gold surfaces. The team of scientists observed that the molecules self-assemble autonomously on the surface, densely packed, side by side like oranges on a shelf. "The suction cups adhere to the surface but they are still mobile and attract one another," explains doctoral candidate Tellkamp. In this way, an artificial epithelium is formed.

The next logical step is to find out if the artificial epithelium works much in the same way as our nasal mucosa. In collaboration with Prof. Olaf Magnussen in the Physics Department of Kiel University atomic force microscopy (AFM) will be used to visualize the light driven, directed transport of nanoscopic particles.

The recent findings are particularly interesting, not only with respect to fundamental research. With artificially ciliated epithelia, a molecular nano-fabrication seems possible -- machines of molecular size would build other machines by positioning chemical products specifically and precisely. Entire production plants could thus fit onto a tiny chip. Other conceivable fields of application include artificial organelles equipped with molecular cilia that are controlled by an external stimulus; or in the more distant future, they could operate autonomously within the bloodstream and carry drugs to the site of a disease.