Biophysics

Your body contains roughly 20,000 different kinds of proteins. Each one is a tiny machine that folds, twists, and flexes thousands of times per second to do its job: digesting food, firing neurons, fighting infections. When one of those machines jams or snaps into the wrong shape, you get disease. But for decades, watching a single protein change shape in real time has been like trying to film a hummingbird’s wings with a pinhole camera. The motions are too fast, the proteins are too small, and the measurement tools introduce too much noise.

Researchers at the University of Queensland just solved that problem. In a paper posted to arXiv on July 17, they describe a silicon-chip sensor that can track the shape changes of a single protein molecule at sub-microsecond speeds, continuously, for minutes at a time. No fluorescent dyes, no averaging over millions of molecules, no physical tether that might alter the protein’s behavior. The device is a nanoscale stethoscope pressed up against a single molecule, and it’s revealing things about protein motion that nobody had seen before.

Place a single cell on a circular micropattern, a dinner-plate-sized arena at the cellular scale, and something strange happens. The cell doesn’t wander randomly. It starts tracing a petal-shaped loop, over and over, circling clockwise or counterclockwise with the determination of a figure skater. About half go clockwise, half counterclockwise. Until they don’t.