The latest iteration of nanoscale drills developed at Rice University are activated by visible light rather than ultraviolet (UV), as in earlier versions. These have also proven effective at killing bacteria through tests on real infections.

Six variants of molecular machines were successfully tested by Rice chemist James Tour and his team. All of them punched holes in the membranes of gram-negative and gram-positive bacteria in as little as two minutes. Resistance was futile for bacteria that have no natural defenses against mechanical invaders. That means they are unlikely to develop resistance, potentially offering a strategy to defeat bacteria that have become immune to standard antibacterial treatments over time.

"I tell students that when they are my age, antibiotic-resistant bacteria are going to make COVID look like a walk in the park," Tour said. "Antibiotics won't be able to keep 10 million people a year from dying of bacterial infections. But this really stops them."

The breakthrough study led by Tour and Rice alumni Ana Santos and Dongdong Liu appears in Science Advances.

Because extended exposure to UV can be damaging to humans, the Rice lab has been refining its molecules for years. The new version gets its energy from still-blueish light at 405 nanometers, spinning the molecules' rotors at 2 to 3 million times per second.