Dr Michelle Dickinson: nanotechnologist on food dye creating see-through mice

Did you ever dream you had X-ray vision when you were a kid? While that might sound like something from comic books, new research published in Science this week could bring us one step closer to making it a reality.

Scientists have found a way to see inside the bodies of living animals without surgery by using a surprising tool: a food dye that is common in America. This breakthrough discovery revealed that the dye, known as tartrazine, can make skin, muscles, and connective tissues temporarily see-through!

Tartrazine is a yellow food dye commonly found in products like Doritos and other snacks in the U.S. The dye doesn’t just colour food; it has an unexpected ability to change how light moves through tissues. Normally, light entering biological tissue scatters because of the different structures inside the body, like fatty membranes and cell nuclei. These structures have a different refractive index from the air around them, which is why light doesn’t travel smoothly through our skin and other tissues.

This scattering effect is what keeps us from seeing through our skin - or anyone else's. However, in this study, tartrazine was found to reduce the amount of light scattering inside tissue, allowing light to penetrate more deeply. The result? Scientists could see through the skin of living animals.

In a fascinating experiment using mice, researchers applied tartrazine to the animals' skin. When rubbed onto the belly, the dye allowed scientists to clearly see the liver, intestines, and bladder beneath the skin. When applied to the scalp, they could even observe blood vessels in the brain!

Even more amazing, the skin returned to its normal colour after the dye was washed off, meaning the effect wasn’t permanent.

To understand how this works, think about what happens when you place a pencil in a glass of water. The pencil appears bent or distorted because light behaves differently when it passes through water compared to air. This is due to something called the refractive index, which measures how much light bends when it passes through different materials. The same principle applies when light passes through biological tissues like skin.

Under normal circumstances, biological tissues scatter light, making it impossible to see through them. The dye used in this study helps certain wavelengths of light pass through tissues more easily, reducing that scattering effect.

While this discovery is ground-breaking, it’s not perfect. The effect is limited by how deeply the dye can penetrate into tissues. For now, the transparency only works on surface-level tissues. However, the scientists are already developing techniques like micro-needling and injections to allow the dye to reach deeper layers of skin and tissue.

Although this study was conducted on mice, the potential applications for humans are enormous. Imagine doctors being able to visualize organs, blood vessels, and deep tissues without invasive surgery. This technology could revolutionise fields like diagnostics, allowing for real-time monitoring of the body’s internal structures with minimal risk to the patient.

The future possibilities are exciting. With further research, this dye technique could become a powerful tool for non-invasive medical imaging, bringing us closer to a world where X-ray vision isn’t just a superpower - it’s science.

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Episode Transcript

Speaker 1 (00:06):
You're listening to the Sunday Session podcast with Francesca Rudgin
from News Talks.

Speaker 2 (00:11):
Be good to have you with us Now. Food dye
has a bit of a mixed reputation, doesn't it. But
finally scientists might have discovered a reason why food dye
is actually quite cool. Doctor Michelle Dickinson joins us Now
to explain more.

Speaker 3 (00:24):
Good morning, Good morning.

Speaker 2 (00:25):
This is this is a pretty interesting discovery.

Speaker 3 (00:28):
Do you know when I read it, I checked the
date because I thought it was April fourth. I was like,
there's no way this is a real scientific document. But
it's published in the journal Science, which is like one
of the highest ones out there. So I had to
go to multiple sources and then read the original because
I was like, there's no way this is true. But
this is true. This is super exciting. So have you
eaten doritos before?

Speaker 2 (00:48):
Occasionally?

Speaker 3 (00:49):
Okay, you know how orange they are? Yeah, well, if
you go to America, they are more orange. In America,
Doritos use a special type of dye. It's called tartrasine,
and they also use it in a drink called sunny
d which is a tremendous bright yellow orange type like juice.
That's never seen an orange in its life and touch

(01:10):
sine is an interesting food colored diye. It's banned across
a lot of Europe, including the UK. We approve it
here in New Zealand, but it is not in our
dourrito's as far as I can see. I did check
the ingredients. But what they did is instead of putting
it on their chips, they took this dye, they turned
it into a paste and then they rubbed it onto
the bellies of mice like a cream. And you go,

(01:33):
where is this going? Well, let me tell you, if
you've ever dreamed of having X ray vision as a kid,
it pretty much gave them that. It literally made the
skin of the mice totally transparent, so that you could
see through the skin to the internal organs of the
mouse throw its belly.

Speaker 2 (01:50):
What I'm curious about, hero, is what was it about
the dye in the first place that made them think
it would have these superperals?

Speaker 3 (01:57):
And how many things are they rubbed into massa?

Speaker 1 (01:59):
I don't know.

Speaker 3 (01:59):
I don't know the answer to that. We're only talking
about the good news stories. So they're able to see
the liver, the intestines, critible ladder through the skin without
doing anything evasive. Nothing was kind of open. The skin
just went transparent. They did the same thing on the
scalp and were able to see blood vessels around the
brain and you just go, that's bunkers, And so you
think about, well, how does it work? Whide does it work?

(02:20):
So it's also do with something called reflective index and
reflective indexes where light, which we used to see, travels
through different media at different speeds. And you know this
if you've ever put a pencil in a glass of water, right,
the pencil looks like it's bent in the water because
the wavelength of light is traveling differently through the water
than through the air. If you ever gotten a swimming
pool and you look at your legs and they look
a little bit weird, that's a reflective index change. So

(02:41):
what they found is this die can actually help certain
wavelengths of light to pass through the tissues more easily,
which reduces the scattering, which is what makes things not
see through. And so yeah, they just basically gave you
X ray vision, at least for mice. They haven't tested
on humans yet. But you go, this is bonkers. Literally
a food die if you could rub it if you

(03:01):
had a truemoil you want to see inside somebody's body,
you could just rub it on them and change.

Speaker 2 (03:06):
Where we do.

Speaker 3 (03:08):
Yeah, so the thing is mice a very thin skin,
so one of the changes. It's only going to work
for as thick or as deep as the dye can go.
So now they're working on micro needling and even injections
of this dye into the skin to see if we've
got thicker tissue like we do as humans, whether or
not work for humans. But the great thing is as
soon as they rubbed the die off, like they washed
it off, it stopped. That was the end of it.

(03:30):
It wasn't permanent. So it literally is the dye on
the skin creating the skin to appear transparent. But yeah,
I think of futures. If you've got a tumor growing
or something just on the surface of your skin that
you want to see underneath, you want to look underneath,
you can make your skin see through. This is bonkers.
Go look at the journal, though it's a journal science,
because there's some I mean they're a bit gory, but
there's some amazing pictures in here of literally the insides

(03:51):
of a mouse that you can see through the skin
and I wouldn't have believed it if I didn't read
it three times.

Speaker 2 (03:57):
And do you think it would be safe to if
we were using it too injeeked?

Speaker 3 (04:01):
Why they haven't done it in huge yet? Let's sort
of and look that tartisine is banned for in many countries,
but the evidence around why they've banned it isn't strong
so and the UK have banned it voluntarily without any
scientific evidence. So what they're saying is it might bring
in hyperactivity, it might bring in some exma, a little
bit of esthma, but they actually haven't been able to

(04:23):
show that with some good scientific evidence.

Speaker 2 (04:25):
So if you go and find it as a product
of Zealand, don't mesh it up into some kind of
paste and put it on your skin, because actually it's
not going to be strong enough for you to see
and sign.

Speaker 3 (04:34):
It's not that the concentrations. Well you can do it.
I mean, it's probably not going to do it any harm,
but it's probably not. So you can buy this stuff
in you just yellow for a bit, Just go yellow
for a bit. And the reason why we have it
here is because we don't have the high level of
ultra processed foods they do in America, so it's not
in all of our things. It's a very common food
ingredient in America. So New Zealand and Australia have decided

(04:54):
to leave it in our system because we just don't
have the range of ultra process foods. But yeah, see
through mice, super fun, go look at the pictures Journal Science,
and it looks like our dreams of X ray vision
as a kid might be coming true.

Speaker 2 (05:05):
Very cool. Still dying to know what it is about
that particular what that particular die that they thought this
will be it.

Speaker 1 (05:13):
For more from the Sunday Session with Francesca Rudkin. Listen
live to News Talks It'd be from nine am Sunday,
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