DNA Origami Switch Flips in Milliseconds, Holds for Hours, Enabling Molecular Machines

Creating machines that operate at nanometer dimensions has long been a goal for scientists, yet producing dependable moving parts that work reliably on that scale has remained elusive. A new study reports a DNA‑based switch that can toggle rapidly between two stable configurations, mimicking the on‑off behavior of conventional electronic components.

Since Richard Feynman’s famous 1959 talk “There’s Plenty of Room at the Bottom,” researchers have pursued the vision of building devices atom by atom. In practice, however, thermal fluctuations keep individual molecules in constant motion, making precise assembly and control of nanoscale mechanisms extremely difficult.

Switches are especially problematic because they must hold a position, transition cleanly to an opposite state, and remain stable afterward. No design had previously achieved that combination at the molecular level.

Now a team at the Technical University of Munich has engineered a switch composed of folded DNA strands that stays locked in a given state for up to an hour and flips in just a few milliseconds when a short electric pulse is applied. The device can be cycled repeatedly without noticeable loss of function.

“Individual devices sustain hundreds of thousands of switching cycles over several hours and remain functional for actuation over several days,” the authors note in their Science Robotics paper. “As a nanoscale electromechanical interface, our device enables applications in molecular information processing, optical nanodevices, and the dynamic control of chemical reactions.”

The switch employs a snap‑through mechanism—a principle common in macroscopic engineering where a structure rests in one of two positions and only moves when a sufficient force is applied, much like a household light switch.

To shrink this concept to a few dozen nanometers, the researchers designed rigid arms connected by flexible molecular hinges, ensuring the system settles into one of two configurations without spontaneous flickering. They used DNA origami, folding a long DNA scaffold with hundreds of short “staple” strands into the desired three‑dimensional shape.

One arm includes an extended lever that serves as the moving element. Because DNA carries a negative charge, an applied electric field pushes the lever hard enough to trigger the snap‑through, flipping the switch. In the absence of a field, the team estimates the structure remains in its chosen state for roughly six hours, and no spontaneous transitions were observed while monitoring 70 switches for an hour.

Durability proved to be a standout feature. A single switch endured more than 200,000 toggles over five and a half hours, while a simplified variant survived one million cycles in three hours, still operating at about 85 percent efficiency. Performance varied among devices, with some failing after only a few thousand cycles and others persisting for days.

The authors attribute failures to a mix of contaminants, surface wear, and chemical changes in the surrounding fluid. Intriguingly, some non‑functional switches later resumed activity, suggesting a capacity for self‑repair.

To demonstrate practical utility, the researchers attached a gold nanorod to the moving arm, creating a tiny light switch that altered the scattering pattern of incident light. In a separate experiment, they used the switch to expose or conceal a molecular binding site, thereby regulating whether additional DNA strands could attach.

This ability to hide or reveal binding sites could be leveraged to switch chemical reactions on and off, for example by controlling enzyme activity. The team envisions such switches serving as “control knobs” for chip‑based biomanufacturing platforms that execute sequential reaction steps.

Significant challenges remain before the technology can be deployed in real‑world applications. Each switch represents a single bit of information, and integrating many switches into functional circuits is still a distant goal.

Nonetheless, establishing a reliable nanoscale switch marks a crucial step toward the broader ambition of molecular machinery. While the dream of fully fledged nanomachines is still far off, this development brings the scientific community a little closer to Feynman’s original vision.