My first thought was: if it's a common food dye, why is this only just discovered?

I mean, Herbert G Wells seems to have guessed such a technique 127 years ago, has it really taken this long for someone to go "hey, I wonder if that would actually work"...?

Also, there's an image at the top of the article seemingly showing a human hand, but later on the article says "the procedure has not yet been tested on humans and researchers will need to show it is safe to use", and watching the video doesn't show that hand image, but does show a clearly fake arm with alongside "the method has not yet been tested in humans", so WTF is up with that?