Category: Research

According to a press release, a team of scientists at the Weizmann Institute of Science in Israel a simple biocomputer (a programmable two-state, two-symbol finite automaton) using DNA molecules and enzymes. The work was reported in the 22 November 2001 issue of Nature. According to the press release, ìCollectively, the computers perform a billion operations per second with greater than 99.8% accuracy per operation while requiring less than a billionth of a Watt of power. This study may lead to future computers that can operate within the human body, interacting with its biochemical environment to yield far-reaching biological and pharmaceutical applications.î

Additional coverage is available on from Reuters, the BBC Online, and the Nature Science Update website.

from the Molectronics dept.
According to a press release (8 November 2001), researchers at Lucentís Bell Laboratories have announced they have succeeded in fabricating an individually addressable transistor whose channel consists of just one molecule. The latest results are a step forward from their work reported in October, in which they announced the creation of the single-molecule transistors. However, they had previously only been able to fabricate these "nanotransistors" as a matrix of a few thousand molecules that worked in tandem. Now, using a new technique, physicist Hendrik Schon and chemists Zhenan Bao and Hong Meng have succeeded in fabricating molecular-scale transistors that can be individually controlled. Their results were reported online in the 8 November 2001 edition of Science Express.

Using two of the nanotransistors, the Bell Labs scientists built a voltage inverter, a standard electronic circuit module that converts a "0" to a "1" or vice versa, creating a NOT gate for computer logic. The Bell Labs device is significantly different from the nanotube-based NOT gate created by IBM researchers announced in August.

Additional coverage is available in this news story from Reuters News Service and this Associated Press news story on the New York Times website.

from the natural-selection dept.
According to a press release, researchers at the Rockefeller University Laboratory of Molecular Neurobiology and Biophysics have worked out the three-dimensional structure of the inner workings of an ion-channel protein complex. Ion channels act to pass only specific atoms through cell membranes, and thus act as biological ëatom sortersí. The channel examined in this study is specific for potassium ions.
The overall protein consists of four subunits, like four staves of a barrel. Inside the protein is a narrower tube called the selectivity filter where the potassium ion is recognized. The selectivity filter works as a sorter that chemically senses the ions as they go through the channel. When it senses another type of ion inside the channel, the filter prevents it from entering. The researchers discovered the structure of the filter is very finely tuned to pass potassium ions very quickly, but to exclude other kinds of atoms.

The work was reported in two papers in the 1 November 2001 issue of Nature. The Nature Science Update website has a brief summary of the research, with some helpful graphics.

from the More-molectronics dept.
A collaborative research team from the University of Arizona and Motorola, Inc. have devised a method to measure the electrical conductivity of a single molecule using contacts bonded to the two ends of an octanedithiol molecule. Many previous efforts to characterize possible molecular wires and other molectronic components have given variable results because the contacts were often simple mechanical contacts, not chemically-bonded connections. In their report in the 19 October 2001 issue of Science, the UA/Motorola team describe a method for creating through-bond electrical contacts with very small (2 nanometer) gold particles bonded to single molecules and the achievement of reproducible measurements of the molecules' conductivity. A schematic image is also available.

from the Molectronics dept.
Researchers at Lucent Technologiesí Bell Laboratories report they have created organic transistors with a single-molecule channel length. The companyís press release, along with videos of a press conference and interviews with the principal researchers, are available on the Bell Labs website. The research was reported in the 18 October 2001 issue of Nature; additional coverage ran in the New York Times (18 October 2001).