A colourless food additive sometimes found in snack items has the potential to render skin translucent, making its internal organs visible, scientists have discovered.
Scientists discovered that by applying the dye to the skin, they could visually observe the blood vessels in the brain and watch as the organs and underlying muscles responded.
The researchers carried out their study using mice. However, they believe the dye is safe to use in other animals, and it may be feasible to use it in humans.
The dye is a food colouring called tartrazine, used for its yellowish hue. However, the same colour means it absorbs light, particularly blue and ultraviolet light.
We're usually unable to see through skin because it scatters light, much like fog does. However, this colour works by altering the way skin bends light – a change that prevents it from scattering as much, making it appear more transparent to the eye.
Scientists can easily apply the pigment: they rub a mixture of the colouring dissolved in water on to the animal's skin. Shortly after, it becomes transparent, as it seeps into the skin.
Researchers were then able to see the blood vessels and organs beneath, and even watch the muscle contractions that occurred as the mice's digestive system worked.
After the tests have been completed, the dye may be washed off and the effect will be undone. Any of the dye that remains in the skin will be absorbed and then removed as waste through the urine.
The dye itself is safe for living organisms, which is fortunate because it's already used in sweets, snack crisps and other edible items. It has also been given regulatory clearance by the US National Food and Drug Authority as safe for use in food products.
It is still unclear whether the process would be effective for humans, given that human skin is 10 times thicker than a mouse's skin. Researchers suggest that it might be possible to use more dye or a different delivery method to penetrate the skin fully.
But doing that could potentially enable doctors and healthcare professionals to gain a deeper understanding of what's going on inside a patient's body.
“In human medicine, we currently make use of ultrasound to examine the deeper parts of the living body,” Ou said. “A lot of medical diagnosis platforms are very costly and out of reach to a wide range of people, but platforms based on our technology should not be.”
.
.
