Dingcheng Sun

Light we can't see but feel as heat turns out to be the key to cellular life. A new type of microscope uses waves 2000–2500 nanometers long, three times longer than red light, and such waves barely scatter in tissue. Thanks to this, the device peers into a tumor spheroid like a flashlight through frosted glass, illuminating individual molecules.

Inside every cell, there are tiny power stations — mitochondria. They burn nutrients and store energy. Two helper molecules, NADH and FAD, oversee this process. Previously, they were detected by their faint glow, but it was dim, and signals from different molecules overlapped. The new microscope works differently.