How proteins are being tweaked to be quantum sensors inside the body Premium

Learn how modified fluorescent proteins are evolving into quantum sensors, enhancing our understanding of cellular processes.

For decades, fluorescent proteins have been among the most powerful tools in biology. They glow when illuminated, allowing scientists to see where molecules are inside cells and how they move. From tracking cancer cells to mapping neural circuits, these luminous markers transformed the life sciences, work recognised with a Nobel Prize in 2008.

Now, two major studies published in Nature suggest that fluorescent proteins can do more than glow. Certain fluorescent proteins can be modified to detect magnetic fields and radio waves from inside living cells. In effect they behave as quantum sensors, devices whose operation depends on the behaviour of electrons at the smallest scales.

Until recently, quantum technologies were confined to ultra-cold laboratories filled with specialised equipment. Biology by contrast has been viewed as an unlikely home for quantum effects. Living cells are warm, crowded, and constantly in motion — conditions thought to destroy fragile quantum states.

The new results challenge that assumption, opening a path towards genetically encoded quantum sensors and a new class of hybrid quantum-biological technologies.

When a fluorescent protein absorbs light, one of its electrons is pushed into a higher-energy state. Usually, the electron quickly returns to its original state and releases energy as light. That simple process is what makes the protein glow.

In some proteins, however, this journey is more complicated. The excited electron can briefly interact with a nearby molecule inside the protein, forming what scientists call a radical pair, two molecules that each carry an unpaired electron.