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Researchers at Stanford University have discovered that a common food dye, tartrazine, can temporarily make skin and muscle tissue transparent. By applying the dye to a mouse’s belly, they could see internal organs like the liver and intestines, and when smeared on the scalp, it revealed blood vessels in the brain. This breakthrough, published in the journal Science, could open up non-invasive medical procedures, such as locating veins for blood draws or spotting deep-seated tumours without surgery.
The dye works by altering the way light moves through tissue, reducing scattering and allowing it to pass more easily. Normally, tissues like skin and muscle are opaque because light is bent as it moves between different structures. However, when the dye is absorbed, it matches the tissue’s refractive index, making it transparent to specific wavelengths of light, especially in the red spectrum. The process is temporary and reversible, with skin regaining its natural colour once the dye is washed off.
While this procedure has yet to be tested on humans, it shows great potential for medical applications and could even help scientists study a wider variety of animals. As researchers refine this technique, microneedles or injections might allow the dye to penetrate deeper, improving its use in imaging techniques. Experts from Imperial College London predict this discovery will spark broad interest, potentially revolutionizing non-invasive diagnostics.
