Let’s make one thing clear: Dorito cheese dust will not make you see-through, or at least it shouldn’t. But as researchers at Stanford University have found, the use of a certain dye that these chips contain could be the key to advancements in optical research in biology.
Published in the journal Science on September 6, 2024, the study ‘Achieving optical transparency in live animals with absorbing molecules’ delved into revolutionary research taking place at Stanford University. In an experiment led by Dr. Zihao Ou, researchers used diluted tartrazine, otherwise known as FD&C Yellow 5, to see through the skin of live mice. The scientists rubbed the dye solution onto the mice’s skull and abdomen skin. After just a few minutes, blood vessels were visible in the mouse’s brain. More interesting still, internal organs and even muscle contractions were observed in the abdomen, showing just how effective this method is for optical research.
The motivation for this research came from a need to see tissue and organs within the body without utilizing invasive surgical procedures. Researchers wanted to be able to see active internal processes. While other methods have been attempted, including fluorescence and microscopy, none have been quite suitable for live animals until this research. One vital aspect of this study was biocompatibility, which means that a material is able to be in contact with a living system without causing negative effects. As of yet, the use of dye has had no significant toxic effects on the mice, with their skin regaining opacity after being washed with water and the dye leaving their body after urination. This shows that this material is biocompatible, which is a success in this study.
This research called for aspects of both physics and biology. The lead researcher stated that this process of turning transparent is actually very fundamental physics, but to those who do not know physics that well, it can seem like a magic trick. The relatively simple physics behind the transparency is that skin is a scattering medium, meaning that light does not travel through it linearly. The yellow dye absorbs most light, and when combined with skin, a translucent effect occurs. This is not to say that this specific dye will lead to these transparent effects in humans when consumed in typical amounts like serving sizes; the concentration of FD&C Yellow 5 used in the experiment was much higher than what would be in food.
Ultimately, the goal of this study is to translate this work into humans. The process could be much harder when translated to use in humans; however, since human skin is about ten times thicker than that of mice, it would take a much larger concentration of the dye for the same effect to take place. In addition, the light of a microscope could not go all the way through a living being, which means that microscopy is not a viable option. This breakthrough could lead to many advancements in optical biology, allowing them “to look at more detailed dynamics”, according to Dr. Ou. The discovery may help to make the future of medicine and biology crystal clear with a substance as simple as yellow food dye.
