By Gabe Romain

The first molecular motor has been created that runs on electricity or light.

Developed by Frederick Hawthorne and colleagues from the University of California, Los Angeles, the tiny motor could power machines on a scale smaller than biological motors such as flagella.

"Given the existence of biological motors, the interest of chemists in designing molecular motors stems from the challenge not only of making even smaller nanomachines that perform controllable motion, but also of creating systems that can be powered with light or electrical energy, rather than depending on the delivery of ATP," say the researchers.

Molecular machines

While the term has come to take on several meanings, "nanotechnology" is used to describe tiny machines that work at the molecular level.

While much progress has been made in developing nanostructures--objects measured in billionths of a meter--mature nanotechnology would involve the ability to manipulate atoms or molecules with great control.

Researchers theorize that such manipulation can be done with tiny actuators and other moveable parts. Some of these parts would require nanoscale motors.

Nanoscale motors consume energy in one form and convert it into motion at the molecular level.

Such motors could be used to power structures thousands of times smaller than the width of a human hair--small enough to ride on the back of a virus.

Besting biology

The smallest nanomachines made to date are based on changes in molecular bonding.

In biological motors, such as those that power muscle contractions, motor molecules function by undergoing shape changes using energy from the biological fuel ATP.

Molecular motors with linear motion have been developed, but only a few molecular motors have been developed that are capable of rotary motion, and none can be run on electricity or light.

Atomic construction

The molecular motor that Hawthorne and colleagues developed is a metal complex that undergoes step-wise rotary motion.

It can be controlled by simple electron transfer processes or photoexcitation.

The motor includes a nickel atom that serves as an axle. This is sandwiched between a cage-like assembly of carbon, boron and hydrogen atoms that rotate around the axle.

The motor could be used to close a valve or a switch, the researchers say, and could function in a liquid, gas and vacuum environment.

"Potential applications of the circular motion include modifying, on command, the properties of a surface or molecule to which the device is attached and blocking and opening specific regions on a surface, such as pores or reactive sites," say the researchers.

The motor is reported in the journal Science.