A municipality food coloring which has the property of absorbing a lot of light temporarily makes transparent the skin of a living mouse, to the point of making the blood vessels of the scalp, the movement of the organs which are found under the skin of the abdomen and the tiny contractile units of the muscles at work. Published in the magazine Science from the group ofStanford University led by Zihao Outhis result opens the way to the possibility of detecting images of internal organs in a less invasive and simpler way.
PROGRESS IN RESEARCH ON TRANSPARENCY OF FABRICS
In recent years, other experiments have been carried out in this direction. For example, in 2014 the California Institute of Technology (Caltech) had made organs and entire bodies transparent by immersing them in a hydrogelwith a technique not applicable on live animals. The technique developed in 2016 at theUniversity of Munich.
A NEW TECHNIQUE APPLICABLE TO LIVE ANIMALS
The technique of Stanford can instead be applied to living animals thanks to the physical principle on which it is based. The dye molecules used have in fact the characteristic of strongly absorbing light when they pass through media such as fabrics they organsare characterised by considerable light dispersion due to their aqueous component.
The dye tested at Stanford is able to modify therefractive index of the aqueous parts of the tissues, absorbing light in the regions near the ultraviolet and blue of the spectrum. In this way, the part of the spectrum that does not absorb light, i.e. the red-orange part, is transmitted deeper through the tissue. The result is an effect of temporary transparencywhich can be removed with a quick wash and does not harm live animals.
THE COLORANT TARTRAZINE AND ITS EFFECTS
The dye used is called tartrazineis yellow and is usually added to carbonated drinkssweets, ice cream, chewing gum and jams, as well as in the capsules of some drugs. By applying it on the scalp of mice it was possible to observe the blood vessels which pass through the brain and, by applying it to the abdomen, it was possible to observe the contractions of theintestine and the movements caused by the heartbeats and breathing. The effect wore off within minutes and, once the dye was rinsed off, the fabrics returned to their normal appearance. tartrazinethe researchers note, does not appear to have long-term effects and the excess amount is expelled from the body within 48 hours.