CHICAGO, March 25 Researchers in Japan have developed a pair of molecular-scale scissors that open and close in response to light. The tiny scissors are the first example of a molecular machine capable of mechanically manipulating molecules by using light, the scientists say.

The scissors measure just three nanometers in length, small enough to deliver drugs into cells or manipulate genes and other biological molecules, says principal investigator Takuzo Aida, Ph.D., professor of chemistry and biotechnology at the University of Tokyo.

Chemists and biochemists may also use the scissors to precisely control the activity of proteins, Aida says. He presented details of the new technique today at the 233rd national meeting of the American Chemical society, the worlds largest scientific society.

Scientists have long been looking for ways to develop molecular-scale tools that operate in response to specific stimuli, such as sound or light. Biologists, in particular, are enthusiastic about development of such techniques because it would provide them with a simple way to manipulate genes and other molecules.

It is known, for example, that near-infrared light can reach deep parts of the body, says Kazushi Kinbara, Ph.D., associate professor of chemistry and biotechnology at the University of Tokyo and co-investigator of the study. Thus, by using a multi-photon excitation technique, the scissors can be manipulated in the body for medicinal applications such as gene delivery.

The scissors-like molecular machine uses a photo-responsive chemical group that extends or folds when light of different wavelengths falls upon it.

Just like "real" scissors, the molecular scissors consist of a pivot, blades and handles. The pivot part of the scissors is a double-decker structure made of chiral ferrocene, with a spherical iron (II) atom sandwiched between two carbon plates. The three-piece unit creates a shaft that allows
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25-Mar-2007