It sounds like magic. Or maybe futuristic Star Trek-level science. Either way, the headlines were stunning: "Scientists use food dye found in Doritos to make see-through mice." No, this wasn't achieved by witchcraft.
Physician and journalist Bruce Y. Lee explains that the process starts with tartrazine, aka Yellow Dye. No. 5. It's a food dye that's used in many products, including Doritos. But the tartrazine doesn't change the chemical composition of the mice's bodies. It changes the way we see the mice.
"The reason why you can or cannot see through something depends on how much light is scattered or bent," Lee explains. If light can go straight through something, it appears transparent. But the more light gets scattered, meaning it bounces when it hits something, the less transparent that thing becomes. When there's enough scattering of the light, you can no longer see through something and it becomes opaque.
Tartrazine powder sits in a Petri dish. Photo by Shutterstock.
Scientists tried different materials that decreased light scatter in body tissue and eventually found one — Yellow Dye. No. 5 — that worked. When they painted it on the bodies of living mice, they could see through the skin to view the blood vessels, muscles, and organs underneath.
The process hasn't been tried on humans, who have thicker skin than mice. If it eventually works in people, it has promising health applications. What if you could see what's happening under your skin without getting an X-ray or MRI? It might also make certain procedures, like threading a catheter or removing a tattoo, easier. But we're a long way off from that.