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Imperfect Diamonds -

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Imperfect Diamonds

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It's not every day that a defect can be considered an advantage - but in the case of a diamond
nanocrystal with a nitrogen vacancy, the very imperfection renders it perfect. Tanya Ha meets the
team of scientists at Melbourne University responsible for creating a nano-diamond sensor that's
providing insider information about cells - including how drugs work and their efficacy.

NARRATION

A human cell - the basic unit of life.

Tanya Ha

We're made up of trillions of them, a bit like this one. There's a lot going on in there, much of
it's still a mystery. Well come with me, because new light is being shed on just how things move in
a place like this. Here at the University of Melbourne, great insights into cell biology are being
made by theoretical physicists. It's not what you'd expect, but then, that's nanotechnology for
you.

NARRATION

Professor Lloyd Hollenberg usually works in the mysterious world of quantum computing. He's now
experimenting with human biology.

Professor Lloyd Hollenberg

We hope to have a new way of seeing inside the cell, using quantum properties. We'd developed a lot
of new ideas in how to use atoms as technology, and so we thought, well perhaps we can actually use
this technology that we've been developing as a new type of sensor that would be of particular
interest in a living cell.

NARRATION

The sensors Lloyd's using are tiny little diamonds.

Professor Lloyd Hollenberg

These nano-diamonds are several tens of nanometres across. In our case fifty nanometres. And that's
roughly a thousand times smaller than the width of a human hair.

NARRATION

Lloyd has a discerning eye for diamonds. He's interested in ones with a very particular flaw.

Professor Lloyd Hollenberg

Within the nano-diamond, there's a defect, and it's actually one of the most perfect defects that
you could imagine, if you're a quantum physicist.

NARRATION

This defect is a vacancy in the nano-diamond's structure.

Professor Lloyd Hollenberg

All the carbon atoms here, they're grey.

Tanya Ha

Yeah.

Professor Lloyd Hollenberg

And you've got the nitrogen atom here ...

Tanya Ha

Yeah.

Professor Lloyd Hollenberg

And where there would have been a carbon atom, you've got the vacancy.

Tanya Ha

You know it's the thing that I really like about this, is that it's the absence of something that's
quite significant.

Professor Lloyd Hollenberg

No, that's right, there's this vacancy here that makes this entire quantum system very special
indeed.

One of the things we use the nano-diamonds for is to use the nitrogen vacancy system itself as a
tiny little compass, when it acts like kind of a GPS-type beacon.

Tanya Ha

The nano-diamonds are suspended in this liquid which Dr Annie Yan then adds to living human cells.

NARRATION

The cells ingest the nano-diamonds by the clever process of endocytosis. This allows the
nano-diamond to have its own membrane-bound capsule inside the cell.

Dr Yan (Annie) Yan

This is of great interest to a cell biologist, because nano-diamonds can be used as a probe to
telling us how those important molecules interact with the cell.

NARRATION

The cells are now ready for a unique quantum investigation involving lasers and microwaves.

Professor Lloyd Hollenberg

What you're seeing is predominantly green light, and that excites the nitrogen vacancy centre. Here
are two wires that guide the microwaves into the sample.

Tanya Ha

So this is what the microscope sees?

Professor Lloyd Hollenberg

That's right.

Tanya Ha

Okay.

Professor Lloyd Hollenberg

So you can see the individual cells here, and there are lots of little bright spots of light. Some
of these are the light being emitted from a nitrogen vacancy centre. If we zoom in to one of these
areas, here we see, you can just see the outline of the cell membrane here.

Tanya Ha

Oh yeah.

Professor Lloyd Hollenberg

And here is the light actually coming out of a single nitrogen vacancy centre.

Tanya Ha

So that tells you the position of a nano-diamond within a cell?

Professor Lloyd Hollenberg

That's, that's right.

NARRATION

Once Lloyd knows where the nano-diamond is, he then applies the microwave.

Tanya Ha

So what more does that tell you about what's happening inside the cell?

Professor Lloyd Hollenberg

Well one of the things that it can tell us is the orientation of the entire nano-diamond, while
it's moving in the cell.

Tanya Ha

These nano-diamond sensors are going to give us a clearer picture of how things move once they're
introduced into living cells - things like therapeutic drugs.

Dr Yan (Annie) Yan

We hope those nano-diamonds can specifically interact with the targeted cells. For instance, cancer
cells, and they enable to deliver those drugs only to those cells, and not impair the functions of
the normal healthy cells.

NARRATION

It's a quantum leap in theoretical physics, that's poised to make a huge impact in cell biology.

Professor Lloyd Hollenberg

To be able to say that we did the first quantum measurement in a living cell, is really quite an
achievement, I think.