Month: July 2001

from the Molectronics dept.
An article in Science News ("Chemists decorate nanotubes for usefulness", by J. Gorman, 23 June 2001) describes work by researchers who have developed a new technique for attaching groups of atoms to the sides of carbon nanotubes, creating compounds with extraordinary strength and conductivity. The article is not available at the SN website, but is reprinted on the SmallTimes website. The work is described in a recent issue of the Journal of the American Chemical Society (123:6536).
The research team was led by James Tour of Rice University and Paul Weiss of Pennsylvania State University. The article suggests the functionalized carbon nanotubes could be used for making electronic circuits that are far tinier than today's silicon-based circuitry. Doing so will require chemically hooking carbon nanotubes to other microscopic electronic components, comments Weiss. One of the functional groups that the Rice researchers successfully attached to carbon nanotubes has exhibited both memory and switching behaviors necessary for electronic devices, says Tour. The researchers are investigating whether a nanotube and its functional groups retain their desirable strength, conductivity, and chemical traits after they're combined.

As noted here on nanodot, a team led by Tour and Weiss announced in June 2001 that they have demonstrated single molecules that switch between "on" and "off" states based in part on conformational changes.

from the step-by-step dept.
Researchers at Stanford University led by chemistry professor W. E. Moerner have gained further detail on how the kinesin molecular motor pulls objects along microtubule tracks inside cells. Their studies reveal that while one end of a kinesin molecule holds onto its cargo, the other end uses a remarkable two-headed structure to grab the microtubule and pull the cargo forward – a process called "kinesin walking" The work is described in the June 2001 issue of Nature Structural Biology.

As reported here on nanodot in June 2001, other research indicates kinesin systems may also harness the energy of random Brownian motions to move along microtubules.

Kinesin molecular motors are also employed in the microtubule molecular shuttles developed by a team led by Viola Vogel at the University of Washington (Seattle) Center for Nanotechnology. The shuttles are capable of moving cargo along engineered paths. Vogel and her co-workers have demonstrated methods of controlling the direction of motion of microtubules on engineered kinesin tracks, how to load cargo covalently to microtubules, and how to exploit ultraviolet light to turn the shuttles on and off sequentially. These are the first steps in the development of a tool kit to utilize molecular motors for the construction of nanoscale assembly lines. This work was described at the 2000 Foresight Conference in November 2000.