Chemistry World Podcast - February 2008

00:10  --  Introduction

02:03  --  Fish skin holds a dazzling secret

04:00  --   Edible antifreeze could take the icy crunch out of ice cream

06:30  --   The chemist who saved evolutionary biology: Richard Corfield tells the story of John Young Buchanan

17:00  --   Non-stick at the flick of a switch

19:36  --   A polymer gel that could prevent skin grafts from shrinking

23:09  --   Biofuels: Martyn Poliakoff tells us how renewable fuel policies could be creating more problems than they solve

29:36  --   Paris's tropical past

32:35   --  What exactly is the smell of a gas leak? And we have a new, safety conscious, chemical conundrum

(Promo)

Brought to you by the Royal Society of Chemistry, this is the Chemistry World  Podcast.

(End Promo)

(00:10   --   Introduction)

Interviewer - Chris Smith 

Hello, and welcome to the February edition of the Chemistry World podcast with Mark Peplow, Victoria Gill, James Mitchell Crow and Ananyo Bhattacharya.   I'm Chris Smith   On the way, longer lived frozen food and smoother ice cream and that's all thanks to a simple protein that we've all heard of.

Interviewee - Ananyo Bhattacharya

A food scientist in the US has found that fragments from the protein, gelatin, could help to make food last much longer in the freezer and also get rid of that unpleasant crunchiness you get from ice cream.

Interviewer - Chris Smith 

More from Ananyo coming up shortly, plus we'll be hearing about the non-stick surface that you can turn ON and OFF.

Interviewee - Mark Peplow

If you imagine the non-stick surface on your frying pan, imagine if you can just switch that ON and OFF, just with a switch and that's exactly what scientists at Bell Laboratories in New Jersey in the States have developed.

Interviewer - Chris Smith 

And we'll also be finding out why the EU's plans for biofuels aren't very environmentally friendly.

Interviewee - Martyn Poliakoff

The same wheat being turned into ethanol can give enormously wide variation from about 10% greenhouse gas mitigation up to 80 or even higher percentage, depending how it is processed and what fermentation technology and so on is used.

Interviewer - Chris Smith 

That's Martyn Poliakoff who'll be telling us about the report written by the Royal Society on the EU's proposals for future biofuels.   Also on the way is the answer to last month's Chemical Conundrum  where Mark wanted help in answering this question.

Interviewee - Mark Peplow

Since natural gas doesn't smell, what's actually added to it to create the familiar smell of gas?

Interviewer - Chris Smith 

No idea.   Well the answer is on the way.   And if you are one of the people who wrote in with the answer keep listening to find out whether you are a winner because we could be reading out your name later in the program.

(Promo)

The Chemistry World Podcast is brought to you by the Royal Society of Chemistry.   Look us up online at chemistryworld.

(End Promo)

(02:03   --   Fish skin holds a dazzling secret)

Interviewer - Chris Smith 

First this week, all that glitters is not gold, but could it be silver? Victoria!

Interviewee - Victoria Gill

Yes.   So, this is about iridescence, it's about the shine that you see on fish skin, which is actually really important to fish because it protects them from their predators when they shine and when they are swimming at shallow depths which is when they are quite vulnerable, they just look like rippling water and Israeli scientists at the Weizmann Institute of Science in Rehovot have studied the crystals -- they're called photonic crystals that fish grow in their skin that reflect light and produce this iridescence.

Interviewer - Chris Smith 

So this is the silver effect?

Interviewee - Victoria Gill

Yeah exactly!

Interviewer - Chris Smith 

So what did they find?

Interviewee - Victoria Gill

They took a sample of the fish skin and looked at the photonic crystals on the underside of their scales in their skin and they found that they are composed of guanine molecules, which is what they expected.   So what they've done is they've compared guanine grown in laboratory and guanine as it forms in the crystals in the fish skin and it was quite a surprising results, because crystals form in a certain shape or pattern because it's energy efficient for molecules to stack up in a certain way; the forces of attraction between each of the molecules are stronger in a certain direction and that's what causes the crystals to grow, but in the fish skin, crystals they grow in the opposite way that they would've expected.

Interviewer - Chris Smith 

So this is a very energy inefficient process, potentially?

Interviewee - Victoria Gill

Yeah exactly! They form into flat plates, so the fish are actually having to expend energy on forcing these crystals to grow in a certain way.

Interviewer - Chris Smith 

It's obviously worth spending the energy because it gives the fish this added evolutionary advantage that they're harder to see.

Interviewee - Victoria Gill

Yes, because these flat plates can stack up in layers and what's important about that is the thickness of these crystal plates and the distance between them corresponds with the wavelength of visible light, so as visible light goes into these crystals, it's disrupted and reflected back which is what produces this iridescence.

Interviewer - Chris Smith 

That sounds brilliant quite literally. 

(04:00   --   Edible antifreeze could take the icy crunch out of ice cream)

Interviewer - Chris Smith 

Well, from fish that perhaps you could eat to a new form of antifreeze which is eminently more edible than existing antifreezes, Ananyo!.

Interviewee - Ananyo Bhattacharya

Yes, that's right Chris.   A food scientist in the US has found that fragments from the protein, gelatin, could help to make food last much longer in the freezer and also get rid of that unpleasant crunchiness you get from ice-cream that's been frozen and re-frozen.

Interviewer - Chris Smith 

But why is ice-cream that's been repeatedly thawed and frozen crunchier like that because we've all experienced that and it's not very nice.

Interviewee - Ananyo Bhattacharya

Yeah!  Once ice cream is thawed out and re-frozen, you get large ice crystals forming and that's what gives that horrible crunchy texture.

Interviewer - Chris Smith 

So what's the new advance that's been discovered by these guys?

Interviewee - Ananyo Bhattacharya

So what Srinivasan Damodaran did was that he used an enzyme to break down gelatin into small pieces and then he found that these small pieces had antifreeze properties.   I think this was a bit of a surprise, but in some ways it's not totally surprising because many animals and insects also produce antifreeze agents and many of these very small proteins as well.

Interviewer - Chris Smith 

Do we get any insights into how those natural antifreezes that are known from the animals you describe, how they actually work?

Interviewee - Ananyo Bhattacharya

Well, they think they know that these proteins bind to ice crystals when they are really, very small and somehow prevent them from getting any larger.   How that works and how they actually stick to the ice crystals that's not so clear at the moment.

Interviewer - Chris Smith 

So this gelatin breakthrough means that potentially we could start just adding the same ingredients as we eat already to foods and they would not make these nasty ice crystals and they would be much more flavoursome potentially.

Interviewee - Ananyo Bhattacharya

Well flavoursome may be stretching it, but yes, that's the idea.   I mean some companies like Unilever, for example, already include some of the antifreeze agents they got from elsewhere in their products.   The problem has been that to produce them in large quantities they've resorted to GM yeast and that's not been very popular with some concerns.

Interviewer - Chris Smith 

Unpalatable with some people; they are harder to digest.   But obviously this is not going to go down to vegetarians though, is it because gelatin of course comes from animals?

Interviewee - Ananyo Bhattacharya

Yeah, well that's true but if you don't mind eating marshmallows or jelly then you can't really have much of an objection to this.

Interviewer - Chris Smith 

So hard science is definitely alive and kicking even if it is the science of soft ice-cream, thanks Ananyo. 

(06:30   --  The chemist who saved evolutionary biology: Richard Corfield tells the story of John Young Buchanan )

Interviewer - Chris Smith 

On the way, how scientists have invented a surface that's non-stick at the flick of a switch and also the chemical clues pointing towards Paris having had a tropical climate in the past, but first to a tale that's over a hundred years old.   It's the story of how a charismatic chemist John Young Buchanan saved Evolutionary Biology  from almost certain humiliation.   In the mid to late 1800s, scientists believed that a jelly like substance lurking on the sea floor that they'd called Bathybius held the key to all life on Earth.   So it took a very sharp mind and strong self-belief to realize and then to tell the biologists why they were wrong.   To tell Buchanan's story, here's Richard Corfield.

Interviewee - Richard Corfield

If you could have stood on the brow of the hill behind the English town of Portsmouth in late December of 1872, you would have seen below you a harbour crowded with warships.   To the left would've been men o' war, the three-decked iron steamers of her majesty's Navy's new dreadnoughts and destroyers, to the right were the government officers, dry docks, cranes, piers, and jetties.   On this side too, were the troop transports and official yachts, the central fairway would've been crowded with pinnaces, jolly boats, cutters and pleasure steamers.   This was the nerve centre of the Victorian Navy.   But what's that in the corner? Almost hidden by the gunmetal grey flanks of warships, you would've seen the three small masts of an unremarkable corvette, a ship tiny in comparison with a hulking leviathans around it, but one that was about to change the face of science forever: HMS challenger.

The objectives of Challenger's voyage as agreed by the Royal Society and the Royal Navy were fourfold:

1.   To investigate the physical conditions of the deep sea in the great ocean basins as far as the Great Southern Ice Barrier in regard to depth, temperature, circulation, specific gravity and penetration of light.

2.   To determine the chemical composition of seawater at various depths from the surface to the bottom, the organic matter in solution and the particles in suspension.

3.   To ascertain the physical and chemical character of deep sea deposits and the sources of these deposits.

4.   To investigate the distribution of organic life at different depths on the deep sea floor.  

There were five scientists aboard.   Charles Wyville Thomson, Emeritus Professor of Zoology at the University of Edinburgh and the expedition's leader; John Murray, a fiery and outspoken Canadian; Henry Moseley a naturalist of Oxford University; Rudolf von Willimoes-Suhm, a young German naturalist who had trained at the University of Bonn and the most enigmatic figure of all, the expedition's chemist, John Young Buchanan. 

The Challenger expedition was largely focused on physical and chemical oceanography, but a significant part of its brief was biological.   Darwin's Theory of Evolution  had come out in 1859, carrying with it the caveat that evolution was driven by environmental change.   This, in turn, implied the unchanging environments, such as the sea floor was thought to be, would harbour living fossils, organisms only known from the rock record on land.   Consequently, Challenger was tasked with investigating whether or not the sea floor really was a silent landscape, but evolution proceeded very slowly amongst the unchanging vastness of the abyssal plains which were populated like Conan Doyle's Lost World  with organisms that were known only as fossils from the sunlit realms above.   Nothing highlighted the importance of this idea more than the concept of Bathybius -- the hottest topic in biology at the time.   In 1868, Thomas Henry Huxley re-examined a sediment sample that had been taken by an Atlantic dredging expedition in 1857.   He found that it contained a white, jelly-like substance.   Examination of other deep-sea specimens showed that this material was found in most of them.   Staining with carmine indicated that it was organic material.   This led Huxley, after Darwin himself, the most famous biologist in the British Empire, to suggest that the floor of the ocean was covered in this substance, which he considered to be the most primitive living material on the planet.   He named it Bathybius haeckelii after his friend, the eminent German biologist, Ernst Haeckel.   Haeckel took the idea even further, suggesting that not only was Bathybius primitive, but that it was nothing less than the missing link between life and non-life.   The senior scientists aboard Challenger knew that an unwritten part of their brief was to find out more about Bathybius, but Wyville Thompson and John Murray were sceptical, neither had ever been convinced that the material, not withstanding the carmine staining, was truly indicative of light and so as the expedition set out, all hands were primed to look for Bathybius.   Even diffident Buchanan, the chemist, knew this as he wrote early in the voyage.

Interviewee - Ed Hutchinson Excerpts from Buchanan's Diaries: (clock ticking sounds) 

It was not only expected that the bottom of the sea would be found every where covered with calciferous deposit, but it was believed to have been shown that the mud at the bottom of the ocean was everywhere associated with an all-pervading organism to which Huxley, its discoverer, had given the name, Bathybius.

Interviewee - Richard Corfield

Challenger's voyage lasted four long years and as they sailed south through the Atlantic to Cape Town and then onto the vicinity of Antarctica and the Great Southern Ice Barrier, Buchanan and the naturalists aboard laboured to isolate Bathybius.   Eventually, it seemed that they had struck gold.

Interviewee - Ed Hutchinson Excerpts from Buchanan's Diaries: (clock ticking sounds) 

Mr. Murray who had been working according to the directions given by the discoverers of Bathybius had actually observed a substance like coagulated mucus which answered in every particular, except the ones of motion,   to the description of the organism.   As chemist of the expedition, I looked at matter from a different point view from that of a naturalist.

Interviewee - Richard Corfield

Buchanan decided to evaporate the water from fresh samples dredged from the bottom of the ocean, theorizing that the residue of Bathybius would inevitably have to be left behind, but he drew a blank.   Once the seawater had been evaporated, there was nothing left, but a barely perceptible greyish powder without any sign of carbonization or burning that might indicate the presence of organic matter, as Buchanan tested and tested and as Challenger sailed from Australia up to the Great Volcanoes of Dutch East Indies, he began to uncover a truth that, however, unpalatable to the naturalists excited him; he was beginning to realize that carmine staining was not uniquely diagnostic of life.

Interviewee - Ed Hutchinson Excerpts from Buchanan's Diaries: (clock ticking sounds) 

Haeckel relied chiefly on his faculty of being stained by carmine as evidence that the body which he was examining was organic, but sulphates of lime is prepared by the precipitation of a aqueous solution of calcium salt by alcohol is a perfectly amorphous flocking precipitate, which is coloured intensely by carmine and the colour is fast as against treatment with spirit.   The naturalist on board had great difficulty at first in believing that this reaction was not as Haeckel had thought it was, absolutely decisive of the organic character of the body.

Interviewee - Richard Corfield

Eventually Buchanan was ready to tell the others that Bathybius was a myth.

Interviewee - Ed Hutchinson Excerpts from Buchanan's Diaries: (clock ticking sounds) 

There remained but one conclusion, namely, the body which Mr. Murray had observed was not an organic body at all, and on examining it and its mode of preparation, I determined it to be sulphates of lime which had been eliminated from the seawater, always present in the mud.

Interviewee - Richard Corfield

Bathybius was not an organism at all.   It was a chemical artefact caused by the reaction of the preserving fluid with seawater.   Wyville Thompson and John Murray agreed that Buchanan's findings were conclusive and with some trepidation Wyville Thompson wrote to Huxley to tell him that not a trace of his beloved Bathybius had been found.   Huxley, not only a great scientist, but also a gentleman of stature, realized his error and capitulated immediately and gracefully withdrawing what he called 'the mistake' in an article published in the journal Nature.   Huxley never mentioned Bathybius again, although Haeckel was not as willing to give his eponymous organism and continued to believe in it until his death.   Eventually HMS Challenger docked again at Portsmouth in May 1876 and the crew disbanded.   Wyville Thompson died soon after of overwork and it was left to John Murray to finish the 50 volume report of the voyage.   John Young Buchanan took a lectureship in Cambridge for four years, but his heart was not in it.   With an existing personal fortune and distaste for administration, he had no use for university life and spent the final years of the 19th century exploring the oceans of the world aboard the yacht of his friend, Prince Albert of Monaco.   He moved to America when the First World War broke out and when it ended, returned to live out the rest of his life in a west end hotel.   He died in 1950; the last of HMS Challenger's Scientifics.   His obituary reads "he was not a man who made friends very readily and he certainly did not wear his heart on his sleeve, but once a friend you were always a friend,  for he was a man whose quality of heart equalled the quality of his brain".

Interviewer - Chris Smith 

Oxford based scientist and Science Writer, Richard Corfield telling the story of the expedition of HMS Challenger.   The extract you just heard is based on Richard's book, 'The Silent Landscape:   The Scientific Voyage of HMS Challenger', which is out in the bookshops at the moment.   The extracts from Buchanan's Diaries were read by Ed Hutchinson.   Thanks Ed.

(Music)

(17:00   --   Non-stick at the flick of a switch)

Interviewer - Chris Smith 

Most of us own something non-stick and it's a wonderful technology, whether you are frying an egg or using chatter-free windscreen wipers, but now Mark, scientists have come up with a Teflon effect that you can actually turn ON and OFF.

Interviewee - Mark Peplow

That's right, if you imagine the non-stick surface on your frying pan, imagine if you can just switch that ON and OFF just with a switch and that's exactly what scientists at Bell Laboratories in New Jersey in the States have developed.   The way that they've done is, detect the sort of materials that you'd normally find on a non-sticking frying pan, fluoropolymers and coated them over nano-nails made out of silicon.   Now these nails look pretty much like the nails you'd find in your shed.   Apart from the heads that are just 400 nanometres across that's 200 times thinner than the human hair.   Now they line row upon row of these nails up on the surface and they found that normally liquids, water, oil, all sorts, sort of bead up into droplets on the top - it's non-stick, but they found when you had a current through this, when you put a voltage across the nano-nails, the heads accumulate, this electrostatic charge, which pulls the liquids underneath the nail head and that makes the liquid spread out across the surface, so the surfaces effectively become non-stick.

Interviewer - Chris Smith 

So that sounds phenomenal, but why would you want to have a surface which would be selectively stick or non-stick.

Interviewee - Mark Peplow

Well, the scientists are proposing a couple of potential uses for it.   One, they talk about self-cleaning surfaces.   The other, which I think, is probably more realistic in terms of realizing in a short-term is, use in miniature laboratories which many scientists are now working on called 'labs on a chip'.   Now if you imagine a laboratory that's the size of a postage stamp, you can do miniaturized science in a very efficient way.   You can potentially have hundreds and hundreds of experiments going on, on just a normal bench, and what they would use the surface for in this would be to move liquids around, you can imagine if you have this surface which is either sticky or non-sticky, you move the voltage across that surface and it's going to help a droplet of water roll from one side to the other.

Interviewer - Chris Smith 

How easy is to make and therefore is this a scalable thing?   Will we be able to make literally sheets of this stuff, so that it is usable along the lines of what you've said?

Interviewee - Mark Peplow

At this stage, in terms of manufacturing it -- they're sort of unique items, but if you look at how nano manufacturing has changed over the last decade, we've gone from a situation where many objects, which 10 years ago would be spoke took three months for some poor grant student to make, now you really are making them hundreds of thousands at a time and it is automated.   So I think it's only matter of time, before you really could churn these things out.

(19:36   --   A polymer gel that could prevent skin grafts from shrinking)

Interviewer - Chris Smith 

Well, nano scaling might be bit of massive breakthrough certainly isn't so? Is this, Victoria, which has strong promise for people who have burns?

Interviewee - Victoria Gill

That's right.   This is early stage work, but it's really exciting medically.   This comes out of Sheila MacNeil's group at the University of Sheffield and Sheila MacNeil is very well known for her tissue engineering work.   She makes engineered skin for skin grafts which are used to treat serious burn patients, so if your skin is destroyed by burns, you have new skin grafted onto your body, and obviously the more extensive the burn the less availability of health skin on your body there is to graft it on, so what Sheila MacNeil's group do is they make the tissue engineered stuff, that's kind of like a store of using your own cells to grow skin.   Now there's a serious problem with skin grafts, in that they shrink and this is a particular problem in children and the inflammatory process and the burn process seem to sort of contract up your skin, so although the graft might be successful and healed you then get shrinkage of the skin on the actual wound.   So at first, Sheila MacNeil's group thought this was just a big problem, but then they actually realized if they can look at why this works and start looking for drugs to combat it then, they've actually got in their tissue engineered skin a perfect model to test it on.

Interviewer - Chris Smith 

Have they any clues as to why the skin does this?

Interviewee - Victoria Gill

It is a process of inflammation and healing and scarring which has its also sorts of complicated biochemical mechanisms, but one very important one that they've identified is the activity of an enzyme called lysyl oxidase and what does is that it causes the collagen molecules in the deep layer of your skin to crosslink and this cross-linking gives collagen its strength but too much cross-linking seems to lead it to shrink up like this, so they've identified an inhibitor of this enzyme called 3-amino-propionnitrile.   If you apply this to the skin it seems to prevent this cross-linking, so it inhibits the enzyme, stops the cross-linking, and it prevents the contraction.

Interviewer - Chris Smith 

That sounds good, but the one potential problem I can immediately think of is you wouldn't want that going everywhere in your body because in the right place at the right time that amount of cross-linking is ideal, so how do you confine the effect just to the skin?

Interviewee - Victoria Gill

That's the issue and this is a really nice example of how the team have got together with another group of scientists in a different discipline.   So they need a topical treatment and another group in Sheffield led by Steve Armes working on polymers that are specifically developed to be biocompatible so that you can put them onto your skin or even into your body and they won't harm you, they won't be toxic, so they got together with Steve Armes and he has developed triblock copolymer that's a perfect vehicle for their enzyme inhibitor, so you put the drug and your copolymer together and the polymer gel releases the drug slowly but over a reasonable period of time, over about 48 hours, and you have a good topical treatment.

Interviewer - Chris Smith 

When you apply this drug in their model on the skin in culture, what does this actually show when you subjected to, sort of, burn conditions?

Interviewee - Victoria Gill

Well, that's the really great thing is that the model itself is tissue-engineered skin, it is human skin, so they've got this great 3-dimensional model and they can burn it and show that it contracts in the same way that these skin graft do and when they burn their tissue-engineered skin, it contracts by about 80%, but when you apply the drug to it topically, it only contracts by around 60%, so they are getting a really significant result with that drug.

Interviewer - Chris Smith 

Very encouraging indeed and we wish them luck with that as they move towards trials in real patients.   Thank you, Victoria.  

(23:09   --   Biofuels: Martyn Poliakoff tells us how renewable fuel policies could be creating more problems than they solve)

Interviewer - Chris Smith 

And now onto a subject that seems to feature in almost every episode of the Chemistry World podcast and that's biofuels.   The EU have set some very ambitious targets for greenhouse gas emission reductions.   In fact by 2020, they want to see a 20% cut on the levels as they stood in 1990.   They are proposing to achieve this in part with a drive for more biofuel use, but a report compiled recently by group of scientists of the Royal Society argues that "renewable fuels policies are encouraging biofuels that don't cut greenhouse gases and could cause social and environmental problems.   Martyn Poliakoff, one of the scientists involved in drawing up the reports told me why.

Interviewee - Martyn Poliakoff

Well, in the UK, at the moment, the use of biofuels is governed by the road transport fuel obligation, which describes biofuels mainly that they come from a biological source and doesn't really put in any way a life cycle component, to see whether something is actually cutting greenhouse gases or merely just coming from plant materials.

Interviewer - Chris Smith 

So just because it is a biofuel, it doesn't necessarily mean that it is good for the environment.

Interviewee - Martyn Poliakoff

No, because there are whole series of issues, first of all, what you grow and where you grow it; for example, if you cut down rain forests in the Indonesia which grow on peat, the act of cutting down the rain forests before you plant the palms that produce palm oil, releases large amounts of carbon from the peat, which will negate any greenhouse mitigation from the fuel for many years to come and then after that the way that you actually process the fuel can also have quite a big impact. Some ways of processing fuel can be very much better than others and if you look at Richard Van Noorden's article in Chemistry World you'd see that Jeremy Woods from Imperial College at the Press Conference explained that the same wheat being turned into ethanol can give enormously wide variation from about 10% greenhouse gas mitigation up to 80 or even higher percentage depending on how it is processed and what fermentation technology and so on was used.

Interviewer - Chris Smith 

So are you saying then the politicians in producing these guidelines haven't considered the facts pr