The humble plaster is one of the simplest steps on the road to repairing the damaged body, yet it is a marvel of chemical engineering - a miniature hospital, dispensing everything from antibiotics to aftercare. But how does the plaster stick, and how does it allow the wound to breathe, while at the same time keep it dry? Our knowledge of the chemistry of our bodies now extends far beyond plasters. Now we have soap, toothpaste & shampoo that make us smell nice, our parents look younger and our teeth last as long as we do. Check out the lecture to discover more!

Professor Tony Ryan
[Tony enters lecture theatre on mountain bike. He points to the overhead screen displaying a still picture of Tony's healed knee.] Only eight weeks ago, I fell off a bike like this, and this was the result, and now it looks like this. So, what happened to my knee? Why doesn't it look like something out of a horror movie any more, and what are the ways we can help our bodies repair themselves?
Today we're going to explore the chemistry that allows us to keep fit and healthy.

[Tony holds up a plaster.] Most accidents leads to cuts and grazes that are a lot less severe than my knee, and almost instinctively, we reach for a plaster. You see, the injury breaks the skin and that's a natural barrier. It prevents bacteria and fungi coming in, and its first job is to close the gap. But to compare a plaster to a piece of sticky tape would be unfair. Covering the gap is only the start of what this pocket hospital can do.

The first bandages were used in Egypt, we think, because they wrapped up their dead kings and queens as mummies, and if you got a cut in the 1850s, things would look very strange compared to the way they are now. [Music.]

[Black-and-white reconstruction sequence: Tony visits an 1850s pharmacist.] So you'd visit a pharmacist. I've run in from the present century to two centuries ago, and here he is - a rather dodgy-looking pharmacist, and he's preparing a bandage.
It's made from a piece of leather, so what he's doing is, he's mixing, putting glue on and then some sort of herbal remedy. Something that'll make it sting gets put into the middle of the piece of leather.
Ooh! What a horrible one that was. Ah, such pain!

Yeah, this pharmacist is called Hammy, I think, from the way he's acting. Yeah?
They were metal tongs that squeezed the metal on and there wasn't a National Health Service then, so I had to pay him. [Applause.]

[Tony holds up a modern-day plaster.] This is skin-coloured. It's tough and this one breathes. Our beautiful model over here of a big plaster also breathes, but it breathes through perforations, and most of the early bandages that were made out of plastic had those perforations, but these modern bandages can breathe on their own without the need for these obvious holes. But why is breathing so important in a bandage? Well, I'll show you.

[Demonstration to show breathable fabric.] So here is a membrane over some hot water that's not breathable and you can see the condensation.
We can use condensation to develop patterns that I've got on these gold wafers. I'll just breathe on one to show you how it works.
So if there's moisture around, it says "Ri", OK?
So that's our moisture detector, and I'll put one over this obviously breathable bandage, and we just need a little while for them to develop.

So here is the moisture detector from the membrane that doesn't transmit vapour, and here is the moisture detector from one that does. So this breathing is very important.

The transport of moisture across the membrane helps the healing. You see, the bandage not only covers you, but it covers - oops - a big, undamaged area, and your skin's covered in sweat glands. There are three million of them.

You can produce three litres of sweat in an hour. I'm going to weigh myself at the end of this lecture, see how I've done. And it has an important role.
You see, water evaporates and cools you down, and if you cover the skin with something like this, you get no evaporation.

The wounds become soggy and they're very, very slow to heal. So our breathable bandages are made from my favourite molecules.

[Close-up shot of block copolymers.] These are block copolymers and they're designed to be permeable, so the purple chains - these ones here - and the blue chains - these ones here - don't like each other, so they separate, and the colours separate in such a way that you get a structure on a tiny, tiny scale, so this instrument is called an atomic force microscope and we can read the structure, so over there, on the computer screen, is the structure that these molecules have formed.

Those blobs of blue and purple are a thousand times finer than a human hair. You see, the purple chains really like water, but the blue chains hate it, so in our breathable bandage, the water hops from purple chain to purple chain to purple chain, avoiding the bits of blue chain that have all clumped together, and comes out of the plaster.
Now those of you who came here in a waterproof coat or a cagoule had the same types of polymers inside your coats and they did exactly the same job as the membrane does in this bandage. They allowed the sweaty vapour to escape, but in the time between you cutting yourself and putting the bandage on, thousands of bugs can find their way into your body.

Here comes a bug now. Oh, there he is. [Tony chases Ri helper 'Bipin the Bacteria' round lecture theatre/demonstrates power of immune system.]
Here's Bipin the Bacterium and I'm a white cell and I'm gonna catch him. I am gonna catch him!
I missed him! There! I've caught him now, and what these do are, they protect you from invasion.
Your immune system has special white cells and the cells eat the invaders, and both cells die. [Aaah].
I tell you, Bipin the Bacterium isn't the worst thing we've called him this week. [Laughter.] And these dead cells are exuded as pus, and re-infect the cut.

You see, you need some way of sucking this evil liquid away, so here's the pus and away it goes, and this stuff can really, really do you some damage, so the gauze pad that collects the pus uses exactly the same technology as we find in a nappy, so nappies contain a special gel, and the gel can suck up vast amounts of water, so how much water do you think a nappy can absorb?
Its own weight? Twice its own weight? Well, let's have a look.

I need a volunteer to help me fill a nappy. [Laughter] This young man seems very keen! Down you come to help me fill the nappy.
OK, I want you to stand on this end, right, and you need to peep round the corner, yeah, when I tell you to, and read the scale. What's your name?

[Jaygo] Jaygo? Pleased to meet you. You all right? Good.
So here's a nappy. See how thin it is. Now put it on.
It weighs 22 grams, OK. I weighed it earlier. Now this - feel it - it's a warm liquid, isn't it. We're gonna pour it in here and you need to be careful, OK.
I tell you what, I'll hold it down here and you pour it in for me.
Whoa, whoa, whoa, whoa, whoa, whoa, whoa, whoa, whoa, whoa!
I bet you've never filled a nappy that fast before, have you! [Laughter]

OK.
See, we've poured the liquid in, but the membrane on the top is still white.
It appears dry, and we've already put - let's have a read - we've put [200 grams] 200 grams - wow! - so we've already put 10 times its own mass in there.
Let's see if it takes some more. See, it goes in really, really quickly, yeah?
What I'd like you to do for me is have a feel. Does the surface feel dry? [Hmm, no].
No? Really? You don't think so? Are you sure?
You see, I think it feels dry. I'll even wear it as a hat! [Laughter/applause.] Thank you very much. [Applause.]

Professor Tony Ryan
[Further demonstration to show super-absorbent nature of nappy.] But how does the nappy do what it does? It'll absorb far more than even the messiest baby.
It took 250 millilitres of fluid, 10 times its own mass. In fact, I can absorb a litre of water in 5 grams of the material that fills a nappy.
So I need to pick it up, give it a shake as it goes in. So these are the granules that are inside your nappy. Better put them all in.
If I don't follow the recipes, Annie gets quite upset. Put the right lid on, shake it around.

You see, these molecules are really thirsty, and what they'll do is, they'll absorb the liquid.
They're used in hospitals to clean up spills and the polymer molecules want to dissolve, but they can't dissolve 'cause they're linked together, just like the strands on the web, so they'll solidify a whole litre of water. That's 200 times their own weight.
[Applause]
But when you put your nappy on, it's all well and good having something that'll absorb all this bodily fluid, right, the stuff that oozes out - the blood, the pus.

You need to stick it on, and you need to use a glue.
Now in earlier lectures, we've heard about all sorts of strong glues used to stick training shoes and jumbo jets together, but to show you the kind of glue we need in a bandage, I'm gonna pick on you. [Demonstration of the 'sticky' plaster.]
Hold your arm out. I am a corn fan too, you see, right? I'm gonna put the bandage on, just leave it to settle a while, right?
[Tony puts the plaster on the boy's arm.]
Really suits you, that colour, by the way. Right?

What I'm gonna do now is, I'm gonna peel it off.
I'm gonna try.
It's stuck on really well, is this. Right, are you ready? [Yeah].
Did it hurt? [No, it's all right].
Oh! Are you sure? I'll get a bigger one! [Laughter.]

See, when you peel the bandage off, it hurts because the glue is quite strong and it takes skin cells off, and the more that get ripped off, the more it hurts, so why not have a glue you can turn on and off?
It sounds a bit odd, but Annie's got one here, so on it goes.

[Tony and Annie demonstrate properties of plaster sensitive to ultra violet light.] Yeah. And shall I try and..., (Hmm hmm.) Oh. Can you see?
It's lifting my skin up, yeah?
That's the cause of the pain, but under here is a special adhesive.
It's an adhesive that's sensitive to light. It's sensitive to blue light and ultraviolet light, and the molecules stick because they've got all these dangly ends, and the dangly ends are reactive, and the ultraviolet lamp makes the sticky ends stick together, so if they're stuck to each other, they won't be stuck to you.

So what happens is, the bandage'll no longer stick to my skin and it'll almost fall off.
Shall we have a go? [Hmm hmm].

Right.
This light-sensitive plaster is going through trials at the moment. It came off very easily with less pain than our friend over here experienced, and it's just an example of how plasters are evolving.
Now if you go to the chemist's, you can get plasters that are impregnated with all kinds of chemicals, from antibiotics that fight infection to growth factors that encourage new cells to grow and plug the cut.

Now if I'd fallen off my bike a hundred and fifty years ago, I might not have been so lucky.
The wound might have healed up nicely, but it's far more likely that I would have got an infection, and in those times, this might have cost me my leg or maybe even my life.
It's sobering to think that the average life expectancy in the UK has increased from 45 to 75 in the last century.

Now some of this progress is down to medicine - drugs that kill bacteria, viruses and fungi.
But now we understand how infectious bacteria and viruses get into our bodies, and we can develop ways to deal with them. Now we know how to sterilise, so all these devices come in a sterile packaging, killing the nasty infectious material before it gets close to our bodies, but it's also very important in developments in personal hygiene.
You see, clean water, soap, shampoo and toothpaste also serve to extend our lives and these are the things we'll be looking at next.

Today, we use products like soap and toothpaste to keep our bodies clean and free of dirt, because this dirt is the favourite food of bacteria that can cause us infection, so if these personal hygiene products are effective at keeping us clean, they'll also be effective at keeping us healthy.

Michael Faraday started these lectures in 1826 and life was very, very different then, especially when it came to personal hygiene.

To help us show this, we ran an experiment. Please welcome Tony and Adam. [Applause.]

[Tony and Adam run downstairs to the lecture theatre floor.] So over you come, boys. How you doing?(Fine) Which one are you? (Tony.) Pleased to meet you, Tony. You must be Adam then. (Yeah.)
Pleased to meet you, Adam.
OK, now, you helped us out a lot, so we got you to follow the personal hygiene habits of the Georgian age.
First we asked you not to brush your teeth and only to wash with cold water and no soap for a whole week.
How did you find it?

Tony
I found it quite hard.

Professor Tony Ryan
Did you? Oh, that's a surprise.
I thought you'd enjoy it! [Laughter.]
Right, so why was it hard?

Tony
It's because I'm used to washing like every day, (Oh, right.) having a wash in the morning, but I couldn't.

Professor Tony Ryan
[Overhead screen shows footage of teeth being cleaned with bicarbonate of soda.] OK, well, let's have a look at what we made you do.
It's toothpaste, yeah? So this is you, isn't it. (Yeah.)
So, turn round. Tell them what you were doing.

Tony
I had to brush my teeth with bicarbonate of soda.

Professor Tony Ryan
Right, so in the 1820s, bicarbonate of soda was the toothpaste of choice, (Yeah.) right?
What did it taste like?

Tony
It wasn't very nice and it stuck to the back of my teeth. (Oh, did it.)
Yeah.

Professor Tony Ryan
You know, your Mum uses that if she bakes a cake and it's called baking soda, but did it get your teeth clean? (Yeah.)
Right. You know why it got your teeth clean? (No.)Well, it's a very good abrasive.

It's like sandpaper. It just scratches all the gunk off. (That's horrible.)
But that's what normal toothpaste does, so there's nothing wrong with that, and how about your brother Adam?
What did we do to you?

Adam
I had to wash my hair in lard.

Professor Tony Ryan
[The overhead screen shows footage of Adam washing his hair.] You had to wash your hair in lard? Nah! Surely it was soap? (No.)
OK, well, let's have a look. Yeah. So what he's doing now is, he's scraping soap from a bar. It wasn't lard at all. [Laughter.]
What was it like to do? How did it feel when you washed your hair?

Adam
It was like normal soap.
It was a bit stickier.

Professor Tony Ryan
So it was like normal soap, but a bit stickier, OK.
Oh, dear me, and that was a week's worth of muck, that, wasn't it.
How did your hair feel before?

Adam
It was all right. It was like smooth, but then after it felt like straw.

Professor Tony Ryan
[Tony offers a box to the boys.] It felt like straw.
All right, so I'm gonna make you an offer. (Oh no.)
Two for one. Two Georgian to one modern.
Will you take it? What would you take? (Modern.)
Modern. And you? (Modern.) Modern.
Well, thanks a lot, boys. You've been good sports. [Applause.] Well done.

Professor Tony Ryan
He was half right. The soap was made from lard, but it was soap.

You see, soap is made by reacting a fatty acid with an alkali, and in Georgian times, alkali was very expensive because it's made, or it was made, by burning bones, so only the rich could afford it, and until 1852, there was a tax on soap-making, just like there's a tax on petrol now.
So soap was made in big, large vats and they were locked with a big padlock.

Only the tax man had a key to unlock the vat and you couldn't make the soap secretly and sell it on the black market, so there were soap police wandering round looking for contraband soap. But times have changed since then. Soap's now cheap, but has there been a change in soap technology?

[Demonstration/making bubbles.] So Charlie's gonna come out. She's gonna help me make some bubbles. You go first. (Yeah.)
Look at - oh! Look at those films, how they bend backwards and forwards. Right?
See if I can catch one. Oh, ooh! Shall we have another go? Oh, sorry about the AFN's [applause] ... cheers, Charlie.
It's because of the bubbles that the soaps are so useful to us.

[Tony holds up coloured chains to demonstrate parts of molecule.] You see, the soap molecules are in two bits, and I'm gonna describe them using two molecules. One molecule has a bit that likes water and we call that hydrophilic, and the other molecule, the other part of the molecule hates water and we call that hydrophobic. Sometimes the two parts of the molecules are chains and sometimes there's what's called a head group and a tail group, but they work the same way.

You see, water is a very sensitive molecule. It gets upset by the bit of the chain that doesn't like it, so what it does is, it turns its back on that piece of the molecule, as do all the other water molecules around it, but this bit of the chain, the hydrophilic part, this is a peacemaker, so what it does is, it gets in the way and all the hydrophobic parts of many molecules clump together and the hydrophilic parts poke out and they make something that looks like this [Tony holds up coloured chains] - so all the hydrophobic bits are in the middle and all the hydrophilic bits are on the outside, and we call them micelles and we can use these to remove stains.

See, what happens is, the hydrophobic part will bury itself in a stain and here's a big greasy stain, and all the hydrophobic parts will stick to it, surrounding the dirt and lifting it off your skin or grubby football shirt.
Wow, marvellous. Thanks, Bipin.
And we got some kids from St Wilfrid's School in Sheffield to help us demonstrate this.

You see, when there's not much soap around, single soap molecules wander around on their own and when they stumble across a stain, the hydrophobic parts bury themselves on the inside, getting as far away from the water as possible.
More and more soap molecules arrive and eventually the stain gets surrounded and lifted off, but when there are lots of soap molecules around, they've already formed micelles, and as they come across a greasy stain, they envelop it and lift it off.

So let's look at how soaps have changed since Georgian times and look at how we wash our hair in a bit more detail.
Well, you all know what hair is. It grows out of follicles like these [close-up shot of hair follicle].
There are 100,000 follicles on most of your heads and hair's just a funny kind of skin really.

You see, we usually use soap on our skin, and shampoo is mostly soap. It's the soap that captures the dirt, just like we saw on the screen, but as we all know, modern shampoos make your hair feel soft, full of life, right?
At least that's what the adverts tell us, and this actually isn't just marketing.

[Tony holds up shampoo bottle.] You see, inside this bottle of shampoo are a number of ingredients that are designed to make it kinder to your hair.
Soap's there. It's sodium lauryl sulphate, but there are all sorts of other ingredients to protect your hair from the harshness of the soap. So we'll take a closer look at the hair. What does harshness mean?

Well, harshness is what happens to the hairs when they're washed, so at the far side, you can see a hair that's scaly, and that's close to your scalp. In the middle is a hair where most of the scales have fallen off, and at the end is a hair where all the scales have fallen off.

It's a protein called keratin. It's found in your skin and nails. It's tough and it makes your hair strong, but the alkaline nature of the soap means that it gets ripped off and your hair has no scales on when it feels all dry and straw-like, but the world of personal care products never stands still.

It's no longer a simple matter of applying shampoo, especially if you're fashion conscious. I bet most of you use conditioners, don't you, and I'm gonna show you how they work.

You see, the shampoo removes the dirts and oils and these are replaced by the oils in the conditioner, and you get that soft, tangle-free look.
The hairs get separated.
You get a smooth, shiny coating because the hairs are made smooth and they reflect the light more, but now you can buy conditioning shampoos.

Conditioning shampoos? That doesn't make any sense.
The conditioner's an oil, so the shampoo's designed to take anything that's oily away. How does that happen?

Well, I'm gonna show you the sneaky way of getting the conditioner onto the hair so it's not taken away, so it contains these marvellous polymer particles that get coated in soap.

[Demonstration to show use of conditioners.] When you're washing, there's hardly any water around. It's mainly soap and the soap stays on, but when you rinse, off comes all of the soap molecules and this exposes the polymer particle.
This now falls out of solution and deposits the polymer and the conditioner it contained.

Now demonstrations like this are classics of the Royal Institution Christmas lectures - a bit Heath Robinson, but you get the point. [Laughter/applause.]

Now I got a message from a lady called Daphne Richmond after I'd been on the radio last week talking about conditioning shampoo and she said they left too much silicone in your hair, but these girls from Sheffield High School don't think so.
Do you want to come out and tell us what happened?

[Girls with Unilever technician give Tony the results of the experiment.] So if we go over. So this is Carol. (Hello.)
Hi, Carol, how are you doing? (Hello.)
And your name? (Charlotte.)
Hi, Charlotte, how are you doing? (Fine.)
(Esra.) Esra? How are you doing? What happened to them today?

Carol
Well, I shampooed their hair in a half-head method. (Right.)
I shampooed the left-hand side with a clarifying shampoo and the right-hand side with a conditioning shampoo.

Professor Tony Ryan
Right, and how does it feel, girls?

Charlotte
Well, the one that we conditioned feels a lot smoother. It's sleeker and it's a lot easier to comb (right) when it was wet.
On the side that we only used shampoo, it was very knotty when we came to brush it (Hmm hmm.) and it doesn't reflect the light so much and it's a lot coarser!

Professor Tony Ryan
Yeah? It's not as shiny (No.) and it's easy to spot.
Can you tell which side's been conditioned and which side hasn't, just from taking a look?
Do you wanna just give us a flick? We might be able to see then.
Great, thank you very much indeed. [Applause.]

[Hair-washing demonstration by Unilever hair technician.] That wasn't just a demonstration. Let's look at the science behind what happens.
You see, we saw a piece of scientific research. Carol's job at Unilever is to wash hair in a special way so we can measure the shampoo's properties, so she washes hair in two different shampoos.
So here you can see the hair being washed and then, they use a laser light to measure where the polymer particles that wrapped the conditioner up went.

[Close-up shot of mannequin's head.] So this is a mannequin head that's been rotated in a laser beam and then you can pick up where the conditioner particles have gone.
So there's an awful lot of science and technology in the supermarket, sat on the shelf.

You pay no attention to it, it's cheap, but behind it all is some excellent scientific understanding.
You see, these products do no harm to their producer's balance sheets. I used to think, just like you, that all those adverts were pseudo-scientific tosh, but I've learned that that's not the case.
Now I'm sure that you're all worth it, but are they? [Laughter.]

Now you can use soap not only on skin and hair, but also inside the body.
If you remember, I told you that life expectancy had increased greatly over the last century. This is down to a number of things - clean drinking water, personal hygiene and the development of drugs, but as strange as it may seem, we can start to use soap technology inside the body to deliver drugs more effectively.

Why waste drugs by sending them everywhere in your body? Why not just deliver them where they're needed?
[Tony stands by model of a micelle.] Well, here's a micelle.

It's just like the ones that the soap molecules make, except for these.
These are proteins on the surface and they're the key to getting the micelle into a cell in your body.

You see, when a cell's infected, it sticks molecules on its surface that says, "Help me, help me!", right, and now these proteins will bind onto those distress molecules and the micelle will be dragged inside, and once this happens, the micelle will fall apart and the drug's released, and this magic bullet is now being tested to treat diseases like cancer.

You see, the magic bullet's a very modern way of delivering drugs and our ability to repair the human body is growing all the time, but it's only possible because we're beginning to understand the detailed chemistry of our bodies and how to mimic it, and in a moment, I'll show you how we're using this knowledge to construct a new age of medical treatment.

[Applause/music.]

Professor Tony Ryan
[Sequence/rebuilding parts of bodies/Tony makes brick wall.] So far, we've looked at how technology has elongated and enriched our lives, from plasters helping to repair damage and keep us free from infectious dirt - to personal care products that keep us clean and make us look good.
Now I want to jump to the cutting edge of medical technology, so let's start with how we can rebuild parts of our bodies just like I'm building this brick wall.
So let's look at what supports our bodies - bones.
[Close-up shot of skeleton.] "Hey up, John."

So this skeleton is made from bricks and mortar.
The bricks are a mineral called hydroxyapatite and the mortar is a protein called collagen.

You see, the hydroxyapatite mineral gives the bone its strength, whereas the collagen, which is the cement, is elastic and can absorb any sudden change in forces, so it makes bone a superb, strong material that isn't too stiff and rigid and it's ideal for holding our bodies in place.

[Close-up shot of Tony pointing to a section of bone.] Now the bone has a tubular structure, so here's a piece of bone and inside it's a tube.
Tubes are light and rigid, but more importantly, where it needs to be, bone is porous, so as you move away from the rigid tube, you end up with a porous joint.
In fact, it's a smart material.

It responds to the forces, so the amount of bricks and cement vary depending on what you're doing. So if you're working hard, you end up with stronger bones, and if you're lounging around a lot, you end up with weaker bones.

[Tony explains the hip replacement process using a model of a hip joint.] So if we have to do something like make a hip replacement, this is a very common joint replacement in the UK.
There are 40,000 a year, so we need to have a ball and a socket, but it needs to be made out of inert materials, materials that the body won't react to and reject the implant.

Various materials have been tried. First, glass was used. Doesn't sound very clever, that, does it. It shatters under stress.

Some hip replacements used acrylic type polymers, but they squeaked as you walked along.
Now we use a lightweight polymer, a ceramic ball - sorry, a lightweight metal, a ceramic ball and a plastic cup, so the ball is inserted into the bone. This bit's generally necrotic or not in good nick and chopped off, so in goes this piece, but the metal's far from ideal.

You see, it's as strong as the bone, but it's stiffer, so it carries more weight and the bone responds - because it's not got that much stress - by disintegrating, and this can lead to all sorts of problems.

Metals corrode. Hip replacements last 20 years, which in many cases just isn't long enough. Ideally, we want to make a smart material that can respond to its surroundings, something that will last a lifetime and allow people to lead a normal acting life.

You see, trying to find man-made materials that mimic bone takes a lot of time, effort and money, so rather than mimic with an unnatural material, why not grow with your body's own materials? We all know that transplants are possible, but rejection's a big problem, so what we need to do is grow stuff to order.

[Demonstration explaining control of cells.] Now we all come from just one cell, and when we're born, there are 200 different types of cell in our bodies and the reason is that the single cell divides and makes cells that don't know what kind of cell to turn into and they're called stem cells, so here come some stem cells now.

So a stem cell needs to get a chemical called a growth factor, and the growth factor comes along, wiped onto the stem cell and it knows it has to become a new body part, so this one's just been told, "Be a heart cell."

If we damaged an organ, we could implant some of these stem cells, give them a wipe with the appropriate growth factor and repair the organ, but if repair's not good enough, we could replace a whole organ, but then, not only do we have to teach the cells to be different - liver cells or kidney cells - we also have to give them the right shape outside the body, and how can we do that?

Well, the answer lies in something that's completely unconnected to medicine.

It's architecture, so to help me demonstrate what I mean, I need a couple of volunteers. So we need some kind of people who are a bit big, OK, so we'll use the two in the white T-shirts with the squiggles on, up there, yeah? We need you to be tall and have long arms. Down you come. Just these two. [Volunteers stand with Tony.]

[Demonstration using cling film.] OK. Now I want you to start wrapping this up, OK.
This is some special material that's covered in cells, all right, so away you go, both of you. You need to go round and round.
I'll help you get started. Round you go. You can pass it to each other, so you stay there, round it comes. Oh dear, you broke it. No, good, it got stuck.
I'll tell you what, I'll give you a hand, we'll get going. Yeah, round, round, round.

[Shot on overhead screen of Statue of Liberty/further shot showing skeleton of statue.] The Statue of Liberty is a magnificent structure, but the only reason it stays standing is hidden away on the inside.
It's supported by a scaffold, a network of beams and trusses that support its gleaming exterior. You need to go up to the top and down to the bottom as well, if at all possible.
There we go. Now, as ridiculous as it might seem, this scaffolding is what happens when we make replacement organs.
The scaffold's made from a special kind of material. It needs to be inert and impregnated with growth factors and be biodegradable.
How are we doing down there? (OK.)

We've got skin cells left. Good, keep going then. You see, here, I have a screw in my hand. Keep going, you're doing great. These screws are made of a special kind of material. They're designed to dissolve in the body and they're self-tapping and are used for screwing bones back together. Well, I'll tell you what, that's the best nose job I've seen for ages. Thank you very much, the pair of you.

[Applause.]

So what we did there was what's called tissue engineering and it seems rather complicated to me, but we're already starting to do this tissue engineering and can build new body parts.
Up on the screen is a twitching muscle cell and that muscle cell has been made from a stem cell.

It's been treated with the special chemical to turn it into muscle and it's been treated on a scaffold that's friendly, and it's been grown outside of the body, so if we can make muscles outside the body, we can treat diseases like muscular dystrophy or something.

Now let's return to skin. We've seen injuries from crashes like mine and cuts, but how about the worst kind of injuries at all - burns?
[Close-up till shot on overhead screen of burnt arm.] Look at this unlucky person. Yeah. He'd been burnt really badly in an accident and he's injured his armpit.

See, burns can be life-threatening. If you lose more than 50 per cent of your skin, it's highly likely that you'll die and the normal treatment for burns is a skin graft.

Doctors take skin from another part of your body, normally your buttocks, but if the burns are really severe and life-threatening, there's a problem. There won't be enough skin to cover you in grafts. But since the early 1980s, it's been possible to grow skin in the lab and to use your own skin to give you a skin graft and they're used to treat the burn.

Now three weeks ago, some friendly scientist in Sheffield took a biopsy or a sample of my skin and here it comes.

[Close-up still shot on overhead screen of Tony's skin.] So you can see the surgeon's hands holding my skin tight. You can see the little patch of blood and can you see the thing that looks like a cheese plane and that little flap on it?

Yeah, well, that's a piece of my skin, yeah, and it came from here. It's still quite sore actually.
So what they did was, they grew it on a special surface, a Petri dish that had been modified by plasma polymerisation. You can see - almost - the skin on here.

[Close-up shot of dish with label.] In fact, they've stained one of them, so you can see exactly where the skin is, but they obviously don't think very highly of me because they've labelled me up as a bio-hazard. [Laughter.]

So what I'd like to do now is introduce you to the scientists who did this.
It's Graham Leggett and John Laycock who are from the Tissue Engineering Centre. [Applause.]
So, you've being doing some neat things with my cells, culture them up. I think Graham's gonna tell me what you've done whilst we have a look at a sample whilst John fixes it up in the microscope.

Graham Leggett
[The scientists explain the cell process.] We've been making patterns of hydrophobic and hydrophilic areas in thin layers that are one molecule thick, so if we have a look at the micrograph, we can see the cells are lining up along the hydrophilic areas that they like and they're staying right off the hydrophobic areas in between.

Professor Tony Ryan
And what have you been up to, John?

John Haycock
Well, Tony, with your skin cells, I've made you the ultimate identity badge.

Professor Tony Ryan
[Tony holds up a sheet with his name on.] Marvellous! So how does that work?

John Haycock
Well, what we did is we took a patterned surface that had your name spelt on it that really likes your skin cells, and we grew them in the laboratory and they stuck to the letters, forming your name.

Professor Tony Ryan
Oh, so this is the ultimate name badge, right? It's written with the molecules that define me. Thank you very much, Graham and John. [Applause.]

So these are fun examples and they serve to demonstrate our capabilities, but there's a more serious point to all this. In the future, we could grow body parts and organs to order.

Putting lumps of metal in our bodies and pieces of tape over our wounds could be a thing of the past. Careless cyclists like me could carry patches of their own skin around for use in times of emergency.

But there's every possibility we could extend our lifetimes even further by using this tissue engineering technology, but more importantly, we might be able to make smart composites just like bone that respond to stresses and strains and we don't have to limit this to doing medicine.

We could replace conventional engineering in all sorts of technologies. Imagine the bridge that was built in not quite the right way. It had a design fault, but the material could correct it automatically.

Or a car suspension that changed depending who the driver was, right? These are all possible as we begin to understand more and more about how our own bodies work.

[Applause/music/credits roll.]