Common Food Dye Found to Make Skin and Muscle Temporarily Transparent
coolgopher writes:
"Researchers have peered into the brains and bodies of living animals after discovering that a common food dye can make skin, muscle and connective tissues temporarily transparent.
Applying the dye to the belly of a mouse made its liver, intestines and bladder clearly visible through the abdominal skin, while smearing it on the rodent's scalp allowed scientists to see blood vessels in the animal's brain.
Treated skin regained its normal colour when the dye was washed off, according to researchers at Stanford University, who believe the procedure opens up a host of applications in humans, from locating injuries and finding veins for drawing blood to monitoring digestive disorders and spotting tumours.
"Instead of relying on invasive biopsies, doctors might be able to diagnose deep-seated tumours by simply examining a person's tissue without the need for invasive surgical removal," said Dr Guosong Hong, a senior researcher on the project. "This technique could potentially make blood draws less painful by helping phlebotomists easily locate veins under the skin."
[...] "The most surprising part of this study is that we usually expect dye molecules to make things less transparent. For example, if you mix blue pen ink in water, the more ink you add, the less light can pass through the water," Hong said. "In our experiment, when we dissolve tartrazine in an opaque material like muscle or skin, which normally scatters light, the more tartrazine we add, the clearer the material becomes. But only in the red part of the light spectrum. This goes against what we typically expect with dyes."
The researchers describe the process as "reversible and repeatable", with skin reverting to its natural colour once the dye is washed away. At the moment, transparency is limited to the depth the dye penetrates, but Hong said microneedle patches or injections could deliver the dye more deeply.
The procedure has not yet been tested on humans and researchers will need to show it is safe to use, particularly if the dye is injected beneath the skin.
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Turning tissues temporarily transparent
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