This evening, I will show you something that you won't be able to see.
And it's precisely because you can't see it
that you will see it.
And to start us off, one little question:
What is the colour of gold?
Yellow.
Golden.
Yes, you're right.
Look.
In this vial, I have some water
and some little flakes of gold,
somewhat like in a snow globe.
The gold is beautiful and golden.
But my gold ...
is not golden.
My gold,
it's this colour here.
My gold is ruby-red.
In this vial, I have some water and some nanoparticles of gold.
The nanoparticles of gold are little grains of material,
infinitely small, invisible to the eye.
However, I can show them to you, I took a photo of them.
Here they are.
Aren't they magnificent?
This gold, I heard about it for the first time at university,
in my second year.
One morning, I went to a lecture,
a little tired from revising the night before,
and I remember the professor coming in -
he had a splendid, white beard -
and he put down on the demonstration bench in front of the board
a hot plate with a beaker that had some water in it.
He mixed in two liquids, switched on the device,
and started his lecture.
20 minutes later, the solution that had been transparent -
it had been water -
became red,
red like in my vial, ruby-red, red like TEDx!
He had just made nanoparticles of gold.
I was blown away.
I wanted to know more.
The colour!
The colour.
And the colour comes from an interaction
between the light and my nanoparticles of gold.
We call this phenomenon localised surface plasmon resonance.
I fell in love with it.
(Laughter)
Afterwards,
when I spoke about my nanoparticles of gold to people around me,
generally, it was something they had never heard of,
and sometimes, those who had already heard about it
tended to view it with incertainty, negatively.
They associated it with sanitary or ecological risks.
And I can understand why.
Because historically, there are many examples
of materials that have proved dangerous to man.
For example,
does anyone recognise this object?
It's not a quiz, you just need to guess it's a water jug.
It's a water jug that was sold in the 1910s in the United States.
Let's look at the advertisement.
"Here's Health!"
That's the promise it makes.
Let's read the text.
"To keep that health, you must keep Nature's laws.
They are simple and easy to keep;
but if they are broken,
Nature exacts a heavy penalty from each and every one.
Get plenty of sleep, exercise and wholesome fun.
Avoid overwork, all other excesses,
eat fresh, natural foods, breathe fresh air,
and drink plenty of fresh, invigorating, natural ... radioactive water
from the Radium-Spa."
Yes, this object offers you, provides you with,
water that is radioactive.
Don't start saying that it's typically American.
We had the same thing in France:
Tho-Radia, a company that sold cosmetics at the same time.
"Healthy lipstick!"
And what did Tho-Radia put in their cosmetics?
Ah well, some radium and thorium.
For those who don't know,
these are two chemical elements that are extremely radioactive:
ultimately, these cosmetics won't give you anything but cancer.
(Laughter)
That was meant to be serious.
To sum it up, when you think about it,
a simple, naïve, overtrusting ignorance, mixed with some negligence,
made way for a catastrophe.
It's what gave way to a distrust in the population today
in relation to this kind of novelty.
That's understandable.
But is it really the fault of radium?
Radium isn't a problem in itself; it's the ignorance we had about it.
We know today that we don't need to dismiss ignorance, on the contrary.
We should interested ourselves in it,
confront it, study it, understand it better ...
and take advantage of it.
Get to know it ...
let's get to know my nanoparticles.
Well, I've already shown you the red ones, which are spherical and of gold.
But if, instead of the spheres, we have some minute gold rods,
my gold is going to be blue.
If instead of using gold, I change the metal,
and I try silver,
it can be orange,
or it can be purple,
or it can be -
what do I have in my pocket? -
yellow.
It'll be more helpful with a photo.
You can see in the photo that should come up
that, in general, we can have different colours
just by changing whether its gold or silver,
by changing the shape of these particles.
We can even go a little bit further.
I have one last thing in my pocket.
It's a little disc.
And if you look at this sheet here ...
if I put the disc above my lamp,
you might say, "Well, the disc must be blue!"
However, if I show you the colour of the disc,
this one is opaque and orange.
This phenomenon is called bichromatism,
a property of nanoparticles,
where the colour of the object itself is different from that projected.
However, there's something -
Before I go on,
you mustn't put words into my mouth.
Here, I'm showing you some gold, some nanoparticles,
but I'm not saying that they are harmless.
In this case, it's in solution, in water, or in some solid material,
there's no problem.
If I had, for example, some mercury,
or radium, which, of course, is radioactive,
you would need to take more precautions because it would be dangerous.
Put succinctly, you just need to handle it appropriately.
You just have to be careful.
Well, just what are these nanoparticles useful for?
Well, I personally, during my work at university,
used this gold to develop a gas sensor,
a hydrogen sensor, for applications in energy.
But that's not what I want to talk to you about this evening.
This evening, I want to show you that this gold is also your treasure.
To show this, I have this image.
Here we have a cell.
We see its body in green,
the nucleus in blue, where the DNA is, the heart of the cell.
The little carpet of red stars are my gold nanoparticles.
So, why do scientists mess around
putting my gold nanoparticles in their cells?
Well, the fact is that this cell is a human cell and it is cancerous.
It is diseased.
But the effect that gives the red colour to my gold will have another effect:
my nanoparticles will heat up.
Not a lot, my vial isn't hot,
but enough to heat up the cancerous cell,
and it will die.
Healthy cells, they will survive.
Ultimately, in this vial I have a potential treatment for cancer
that today shows very promising results
for patients taking part in clinical trials.
And it's very often the case
that nanoscience, nanotechnology,
comes up with some very interesting findings
with the potential to really improve our daily lives.
We have learned a great deal in recent decades.
But what I can tell you is, is that, yes, when you wake up in the morning
and on the radio there's about a peak in particle pollution,
you should worry.
Because then, yes, they are dangerous.
But it is still no time to completely forget science.
It's no time to be taken in by hype,
it's no time to fall for marketing propaganda.
Let's take a totally idiotic example.
We all more or less agree that a diet of natural food
is considered a good thing.
But that's not all there is to it:
tobacco is natural,
radium is natural and yet ...
We must take a critical approach,
whether it's GMO or organic food,
or climate change, and so on, and so on.
Ultimately then, with education and a critical approach,
we will have confidence in science, confidence in our researchers.
That way, we will generate innovation,
and thereby learn even more.
For the people here tonight
who are themselves scientists, researchers,
academics of whatever discipline,
I have a favour to ask of you:
Don't let non-experts speak in your name.
Don't leave a void to be filled in by whomever or whatever.
We need to hold out a hand.
Just as here this evening at TEDx, we must be accessible,
we must be open.
For those of you who work in other fields,
those of you who aren't academic staff members,
don't hesitate to look to us,
be prepared to have faith in us.
Come to meet us, in person.
Any day you like, you can send us an email with a question you have.
Because all this learning, all this knowledge,
it needs to be accessible to everyone.
It must be allowed to create beauty in our world,
and form a legacy, one of our humanity.
Thinking about it,
coming back to my nanoparticles,
they're a bit like people:
there are good ones,
there are bad ones,
and you can even fall in love with them.
Thank you.
(Applause)