Woah Science! New Molecule-Sized Submarines Use Ultraviolet-Driven Motor

The “fastest-moving molecules ever seen in solution.”

byLawrence Ulrich|
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It may be a 106-inch squirt of crapulent plastic, but as the smallest car sold in America, the Smart ForTwo still fits two adults inside. Now, consider vehicles so small they could fit inside you. Rice University created the first nanocar a decade ago, a single-molecule cruiser with an organic chassis and axles and four “buckyball” wheels, spheres of pure carbon containing just 60 atoms apiece.

Clearly geeking on Fantastic Voyage, or the 1987 Innerspace version with Dennis Quaid, Martin Short and a then-adorable Meg Ryan, Rice scientists have now gone the submersible route. Built in a 20-step chemical synthesis in the lab of chemist James Tour, these miniaturized subs comprise a single molecule and 244 atoms, with a motor powered by ultraviolet light. Each revolution of the motor drives the sub 18 nanometers forward, with a top speed of less than one inch per second.

“These are the fastest-moving molecules ever seen in solution,” Tour said, notwithstanding the torrential combo of a frat pledge and beer bong.

Rice University

When excited by light, the motor’s rotor jumps from atom to atom a quarter-revolution at a time. That provides suitable propulsion for the 10-nanometer subs, without using or generating toxic chemicals as in some previous nano-scaled power sources. The subs can’t be steered as of yet, but Rice says the motors are powerful enough to drive the craft through solutions of moving molecules of roughly the same size.

“This is akin to a person walking across a basketball court with 1,000 people throwing basketballs at him,” Tour said.

To allow scientists to track the subs without altering their fast operation, the craft were equipped with red pontoons—in scientific terms, “itty-bitty red pontoons”—that fluoresce when hit with a laser beam. Researchers foresee the subs being used to carry medical or other cargo. In a photo, safety-goggled Rice graduate student Victor García-López holds a vial containing millions of the single-molecule nano-submersibles. Just off-camera, we imagine, his fellow science nerds dare him to drink it, so they can watch the subs under attack by an army of white blood cells.