October
Chemistry World Podcast - October 2012
1:05- How on earth can crab shells help beat smelly shoes?
3:50- A serendipitous discovery has solved the paradox behind where methane in the world's oceans comes from
6:38- Amanda Wright tells us about nutraceuticals - food with benefits beyond nutrition
12:12- Replacing cocoa butter with fruit juice can make chocolate much healthier
15:30- Two different types of polymer crosslinking results in incredibly tough hydrogels
18:35- Chris Griffiths discusses the science behind the magical claims of skin creams
24:30- Chemists lend art conservators a hand discovering what the grey crust on a van Gogh is
27:25- Graphene's reactivity depends on the nature of the substrate it is sitting on
30:55- Trivia: Its 100 years since Giacomo Ciamician - the father of photochemistry - suggested using sunlight to produce fuel
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
Interviewer - Chris Smith
This month, a shellfish based remedy for stinky feet. Foods to make you live longer and anti-ageing skin creams - do they really work? We talked to the man who did one of the first proper clinical trials to find out.
Interviewee - Chris Griffiths
We mentioned that this did seem to be able to repair fair to white skin and two days later, people were queuing down the blocks to buy this from Boots, some people were buying it at Boots and then selling it at three times the price on e-bay.
Interviewer - Chris Smith
Hello, I'm Chris Smith and with us for this October 2012 edition of Chemistry World are Laura Howes, Bibiana Campos-Seijo and Patrick Walter.
(Promo)
The Chemistry World podcast is brought to you by the Royal Society of Chemistry, look us up online at chemistry world dot org.
(End Promo)
(1:05 - How on earth can crab shells help beat smelly shoes?)
Interviewer - Chris Smith
And to kick us off, (sniffing sounds) Laura?
Interviewee - Laura Howes
Lo, this is something I found out about when I was in Prague recently for the 4th EuCheMS Chemistry Congress. I met a Portuguese scientist called, Joana Amaral who works at the Polytechnic Institute of Tomar and she's looking at using one of the sugars from crab shells and other crustaceans to try and make your shoes smell less.
Interviewer - Chris Smith
Really, what's the chemical?
Interviewee - Laura Howes
The chemical is chitosan and that's a polysaccharide which is made from chitin, which is found in the shells of crabs and prawns and various crustaceans. This is quite a well known polysaccharide for various uses and one of its many uses is that it's antibacterial.
Interviewer - Chris Smith
Do we know how?
Interviewee - Laura Howes
It basically interrupts the cell wall of bacteria, it breaks it, Kills them.
Interviewer - Chris Smith
And so how would this be implemented in a shoe?
Interviewee - Laura Howes
What Amaral and her colleagues are doing is working to introduce it into the leather at the tanning stage, so actually sort of bind it to the leather as part of the colouring and processing before it becomes a shoe.
Interviewer - Chris Smith
Why should that be particularly difficult or isn't it? is it just groundbreaking in the fact that no one has done it before.
Interviewee - Laura Howes
It's quite ground breaking and that nobody has done it before. People are looking at various sorts of improvements to the tanning process to give function rather than just colour. These added benefits are something that's quite new and chitosan if you process it in an acidic environment, it will bind to natural products and natural materials and luckily in the tanning process, they use formic acid. They have shown that quite simply putting the chitosan in with the other tanning processes gives you anti-bacterial leather.
Interviewer - Chris Smith
Many people will say that actually leather shoes aren't too whiffy and in fact its synthetic fibres in trainers and so on that are really bad, so could they do the same trick but with a pair of Nikes or Reeboks compared with leather shoes.
Interviewee - Laura Howes
I'm not sure about putting it into the processing of the material, but what they're actually looking at is to create a spray version of the chitosan, so hopefully even if you don't have leather shoes that have been treated in this way, you can give it a scrub and hopefully treat your shoes.
Interviewer - Chris Smith
And harmless to the wearer, hopefully so?
Interviewee - Laura Howes
Yeah chitosan is used in quite a lot of medical devices and implants. It's pretty much safe.
(3:50 - A serendipitous discovery has solved the paradox behind where methane in the world's oceans comes from)
Interviewer - Chris Smith
So look out for your chitosan odour repelling shoes pretty soon. Patrick not looking at you for any reason other than you have the next story and sticking with a marine sort of focus.
Interviewee - Patrick Walter
We have a methane paradox. Around 4% of the world's methane is thought to leak from the oceans, but we don't really know where it's coming from. So the bacteria that produced some methane are known to be anaerobic, so they can't survive in oxygen rich environment which is basically what much of the sea is particularly nearer the surface anyway.
Interviewer - Chris Smith
So you're saying there's a sort of paradox in the fact that in the ocean that you find a lot of methane in a lot of seawater that's rich in oxygen. And they shouldn't be there.
Interviewee - Patrick Walter
Exactly.
Interviewer - Chris Smith
So where is it coming from?
Interviewee - Patrick Walter
These oxygenated waters are super-saturated with methane at least compared to the atmosphere, but no one knew where it's coming from. Back in 2008, another team was looking at oxygen loving bacteria and they discovered one that can metabolize methylphosphonic acid into methane. It was drawing off the phosphate to use for metabolism and methane was just a by-product.
Interviewer - Chris Smith
Do you find methylphosphonic acid naturally though?
Interviewee - Patrick Walter
But you don't find methylphosphonic acid naturally. That was the big problem with their theory.
Interviewer - Chris Smith
Right
Interviewee - Patrick Walter
So if there's no natural source, then how on earth can it be responsible for this methane coming from the oceans, but what William Metcalf's team from the University of Illinois discovered, well it's purely serendipity, they're out bio-prospecting, they were looking for new antibiotics in the bacteria of the sea and what they discovered was a cluster of genes, when they expressed them in E. coli, they actually produced this methylphosphonic acid.
Interviewer - Chris Smith
So there is a natural source then?
Interviewee - Patrick Walter
So there is a natural source but it's just been missed all this time.
Interviewer - Chris Smith
So the idea they're putting forward then would be that there are bacteria that are oxygen loving that have these genes that can make this methylphosphonic acid and they then feed that to other organisms that also in the presence of oxygen will break it down.
Interviewee - Patrick Walter
Exactly, yeah.
Interviewer - Chris Smith
This will yield methane in the presence of oxygen.
Interviewee - Patrick Walter
And this yields methane in the presence of oxygen. I mean, they estimate about 0.6 percent of the oxygen loving bacteria in the ocean to produce this methylphosphonic acid, so that's really a huge thing for this compound.
Interviewer - Chris Smith
So what's the implication of this, academic only or does it have climate change relevance?
Interviewee - Patrick Walter
Well, it's always very useful to know where the methane is coming from when you're trying draw up a pie chart of different natural sources and how this measures up against what is manmade. It's probably more than just academic, it is useful.
(6:38 - Amanda Wright tells us about nutraceuticals - food with benefits beyond nutrition)
Interviewer - Chris Smith
Patrick Walter. Now you've heard of food for thought, but who would have thought that food would begin to border on being considered medicinal. Well, welcome to the world of the nutraceutical and our guide is.
Interviewee - Amanda Wright
My name is Amanda Wright and I'm a faculty member in the Department of Human Health and Nutritional Sciences at the University of Wales in Ontario, Canada. When people talk about nutraceuticals they're referring to the biological molecule which is isolated from food ingredients and which has some physiological effects beyond meeting basic nutritional requirements.
Interviewer - Chris Smith
To play devil's advocate Amanda isn't that actually what food is for?
Interviewee - Amanda Wright
Absolutely, but we tend to traditionally think about foods in terms of meeting basic nutritional requirements and then there's been much more interest and research into looking at the intricacies of molecules within food and identifying what are the specific ingredients that have health effects and what we've realized is that beyond simply talking about broad classes of macronutrients or even specific vitamins or minerals, there are tons of other molecules that are actually physiologically active and exert some role in nutritional biochemistry and therefore metabolism and health.
Interviewer - Chris Smith
How would we use that sort of knowledge?
Interviewee - Amanda Wright
Industry is very interested in capitalizing on a better understanding of health effects of various molecules and fortifying so called functional foods which are foods for a lack of better explanation could contain some added nutraceuticals for an additional health kick if you will. A lot of people are using nutraceuticals daily as part of their lives now. We see a lot of people at least in Canada, lot of people are taking omega 3 fatty acid supplements. Those are considered a nutraceutical. As people are getting older, we've seen people turn to luteins, which is carotenoid that has strong evidence that it actually prevents macular degeneration, so people are looking at treating and preventing chronic disease conditions through foods that individually might be known to have some effect.
Interviewer - Chris Smith
Is it not a danger that if we enrich for one particular nutrient; yes it could have a health impact, which is positive in certain circumstances for a certain condition, but may also have knock-on effects, making you more at risk, more vulnerable to other problems.
Interviewee - Amanda Wright
I think that we have to be cautious. We advocate that these molecules have potent effects and can in fact help and so just as we are looking at capitalizing on potential benefits, we need to also recognize that there are two sides of every coin and I think this is part of what is driving various jurisdictions in the world to better define, what these nutraceuticals are and how they're going to regulate them, it's certainly not an easy thing, but that's something that's definitely happening in Canada.
Interviewer - Chris Smith
So, where do you think the really big area for intervention and for nutraceuticals in total is now? Where should we be aiming at or where have we got the most ground to gain?
Interviewee - Amanda Wright
A huge area is chronic disease and association with the burgeoning effects of things like obesity and cardiovascular disease, diabetes. These are conditions that come about over a long period of time related in large part to lifestyle factors including diet, and so there may be a role for foods and nutraceuticals to potentially alleviate some of that burden. And then I think broadly in terms of where the industry is going, there really is this convergence between food and pharma. We are looking at foods potentially of having therapeutic benefits that we would typically associate with drugs. So there is a lot of research right now, looking at understanding better; what is the drug industry been doing in order to preserve sensitive molecules and ensure that they are absorbed and that they are bio-available and seeking to apply that to potential nutraceuticals.
Interviewer - Chris Smith
So, are we getting towards the time when are we going to see an isle in the supermarket marked old people, and you're buying ingredients which were enriched for old people, in the same way that you see isles in the supermarket that says for growing teens or something.
Interviewee - Amanda Wright
I think potentially. We have sections of a large supermarket gearing towards that in terms of gluten free molecules, infant and toddler type foods, we've really moved from a point where I remember going up and health food stores were quite, they were a real niche market, and I remember going there on occasion with my dad and there would be these wonderful bins of strange looking herbs and smelling compounds and similar products are now very mainstream in terms of we can go to our big box stores and purchase fish oil supplements or glucosamine or ginseng supplements. Things have really changed. We are certainly seen the whole idea of personalized nutrition definitely on the rise, it's impacting research in this area. We call this field nutrigenomics and that is the whole idea of diet gene and gene diet interactions and people are really mining their understanding of the genome and nutrition to see what polymorphisms would benefit from the consumption of specific nutrients. So, there is absolutely an element of this that is going in that direction.
Interviewer - Chris Smith
Amanda Wright.
Jingle
Interviewer - Chris Smith
You're listening to Chemistry World with me Chris Smith. Still to come, why some of van Gogh's sunflowers are going a bit grey with age, but first, this tasty morsel on chocolate. Warwick University scientist, Stefan Bon and his colleagues have found a way to replace the less healthy cocoa butter in a chocolate fruit juice. Bibi
(12:12 - Replacing cocoa butter with fruit juice can make chocolate much healthier)
Interviewee - Bibiana Campos-Seijo
Well, we all love chocolates and we all enjoy the flavour. One of the main ingredients of chocolate is cocoa butter, which is actually responsible for that melting in the mouth experience and the flavour
Interviewer - Chris Smith
Lovely
Interviewee - Bibiana Campos-Seijo
.( laughs) yes, the texture as well. The problem with it is that if you are conscious about your health and your diet, you should be looking to reduce the amount of cocoa butter that you add to chocolate and obviously manufacturers are aware of this issue or this problem and they have made that a priority, so actually making a chocolate with less cocoa butter.
Interviewer - Chris Smith
But what does that do to the flavour and texture if it has that very important role, leaving it out, must produce a less enjoyable chocolate.
Interviewee - Bibiana Campos-Seijo
Yeah, what they have done so far is they have replaced the butter with bubbles. The bubbles are quite big.
Interviewer - Chris Smith
Of air?
Interviewee - Bibiana Campos-Seijo
Of air yes. You will be familiar with air for example, and yeah they have done it successfully, but what happens is that the consistency is completely different because you have quite a porous and very light chocolate. So, far, reducing the size of the bubbles beyond a threshold which they have identified as 30 micrometers hasn't been successful, they haven't been able to produce chocolate of good enough quality to manufacture and so. So, these guys have come up with a solution which is actually produced with an emulsion that uses fruit juices, they have been able to infuse the chocolate with that emulsion and the juice actually is encapsulated in droplets that are of the adequate size to give a good experience when you actually eat the chocolate. So the smoothness and the flavour will be something that you would expect to have when you eat normal chocolate, but this one has been infused with the fruit juices.
Interviewer - Chris Smith
So, what in the fruit juice doing this?
Interviewee - Bibiana Campos-Seijo
They've done a, it's a water and oil emulsion. They've put in the oil phase, they've put sunflower oil, they've put the chocolate and they've used three different types of dark milk and white chocolate and they also have molten cocoa butter but as I said before they've reduced the amount considerably. In the water phase, they've put the fruit juice they've used stabilizers, they've used chitosan as well and some food grade silicates and that seem to resolve the problem. It makes it into really sort of homogeneous mixture. So, you know, it makes up for really wonderful chocolate and actually
Interviewer - Chris Smith
And you get very fruity chocolate
Interviewee - Bibiana Campos-Seijo
They say that it could affect the flavour. They've also tried this method with flat coke and coffee and it says that you can actually taste it a little bit but they tried it with a little bit of pure water with vitamin C and apparently you can't taste the difference. So, it's very, very difficult to do it with, you know, when you compare it to normal chocolate, so it's good news all around.
(15:30 - Two different types of polymer crosslinking results in incredibly tough hydrogels)
Interviewer - Chris Smith
So diet chocolates on the way. Bibi thank you. Patrick from one thing that's absolutely wonderful to eat to something you wouldn't want to eat but it's certainly got an interesting texture when you taste it if you have an optic contact lens in your mouth. Hydrogels and even better ones tell us about these
Interviewee - Patrick Walter
Right, hydrogels are extremely useful materials. They have very high water content, this makes them great for applications like contact lenses. But the problem with contact lenses is anyone who has ever worn them knows is that they tear very easily. They're not very strong, they're little bit brittle as well, particularl1y if they've dried out that is.
Interviewer - Chris Smith
So, what is the alternative?
Interviewee - Patrick Walter
Well, an alternative or at least an interestingly much tougher hydrogel is one that's been developed by Zhigang Suo at Harvard University. He took two types of cross link polymer or at least he took the building blocks of these two polymers, alginate which is extracted from seaweed and there's polyacrylamide as well. After he dissolved the building blocks of these two polymers in water and then use UV light to cure them, this creates a crosslink network of these two polymers so they're all completely intermeshed with each other.
Interviewer - Chris Smith
So, you get a mixture of the alginates which links up one way and the polyacrylamide which links up in another way, all mixed together. Why is this better than either alone?
Interviewee - Patrick Walter
So, this produces a much stronger much tougher hydrogel. So, this hydrogel can be stretched to 20 times its original length and then it just snaps back and forms and you can barely notice any difference in its properties. But what makes this possible is that the polyacrylamide is covalently cross-linked. So, these are very strong bonds holding all the strands together whereas the alginate fibres, the alginate polymers have an ionic link which is between them so they tend to link up with things like calcium ions. So, these zap between the polymers and they're kind of weaker. So, what happens when these hydrogels put under stress is that the polyacrylamide hold strong. The covalent link just keep it in shape whereas the ionic link which is between alginates have a lot more give in and they unzip, so they pop apart, calcium ions fall away and this gives the hydrogel much more flexibility than the other ones which are just usually made of one material like a polyacrylamide one and they're just like an ordinary hydrogel, a polyacrylamide gel on its own would be very brittle. It would suffer from tearing problems just like other ones. So, it's this unzipping that makes it much more versatile.
Interviewer - Chris Smith
Apart from contact lenses what else could you do with the material that has these new properties?
Interviewee - Patrick Walter
The research has pointed that their hydrogel is 10 times tougher than cartilage. So, it's a possibility it's a replacement there, I mean, there's other possible biomaterial applications as well.
(18:35 - Chris Griffiths discusses the science behind the magical claims of skin creams)
Interviewer - Chris Smith
Ideal if you want to be stretched to 20 times your original length and then snap back to your original size. I'm just kidding Patrick. Now you can't turn back time or defy the ageing process or can you?. One man became overnight sensation when he appeared on television with clinical evidence that anti-ageing cream appeared to contain more than hype. Chris Griffiths is the Professor of Dermatology at Manchester University.
Interviewee - Chris Griffiths
We were interviewed by the Horizon programme for BBC 2 television. Part of the discussion centred around this over-the-counter products that we had to use which had been supplied to us by Boots and we mentioned that this did to seem to be able to repair fair to white skin. And two days later, people were queuing around the blocks to buy this from Boots. Some people were buying it at Boots and then selling it at three times the price on eBay.
Interviewer - Chris Smith
Very entrepreneurial. Tell us about the assay that you developed in order to test this stuff in the first place
Interviewee - Chris Griffiths
Yeah, so, the assay is an in vivo assay if you like; what we've been able to show is that microscopically in the skin there are two forms of extracellular matrix proteins, these are proteins which gives skin its strength and elasticity. One is collagen as I've mentioned and the other are elastic fibres and this one particular elastic fibre called fibrillin and that anchors the upper layer of the skin and this epidermis to the lower layer of the skin called the dermis and if you think of it like a ground sheet spread on the ground and the fibrillin fibres are like tent picks which anchor the ground sheets to the ground. As you age, and particularly if you are sun damaged you lose those fibrillin anchoring pegs and the skin starts to wrinkle. And we used that knowledge to apply products to sun damaged skin that's on the outside of the forearm just for up to 12 days under tactic occlusion so we could ensure the product got into the skin and then take a little skin biopsy to ascertain whether this fibrillin fibres have been repaired and/or restored. And we knew that retinoic acid is the gold standard treatment prescriptions that could do that and up until that time, there's nothing else we'd seen in that assay and seen under the microscope that could recapitulate the effects of retinoic acids and to our surprise this particular product did that.
Interviewer - Chris Smith
Now if this material in the agent that you tested has this profound effect, at what point does it cease to be some kind of cosmetic application and actually be regarded as a medicine, because the stuff it came from is a medicine?
Interviewee - Chris Griffiths
Yeah, well cosmetic companies have actually some very good scientists working there. They have been able to, you know, develop some very sophisticated technologies, and I guess that we're in this sort rather grey area of between what is a cosmetic and what is a pharmaceutical. In the past, cosmetics were used for improving appearance and cleaning or washing the skin and didn't seem to have any significant effects on skin structure but of course that was before the molecular revolution, our understanding that pretty much anything that goes onto the skin cannot regulate or down regulate genes. And most things that go onto the outside of the skin can to some extent penetrate deeper than just the epidermis then getting to the dermis. And so our technology got more sophisticated, we can see that there are some perturbations with pretty much anything that goes on the skin and that's why it sort of moved from being cosmetics to cosmeceuticals.
Interviewer - Chris Smith
Were they putting the chemicals into these cosmetics with the intention that they would mimic the science albeit at a level that was so low that it may actually not really have any kind of effect?
Interviewee - Chris Griffiths
I think that for the most part was what was happening because if you look at some of the ingredients, you know there's small amount of collagen in there, we know that we're putting collagen on the skin topically, we know that it can't penetrate, it's too large. People, you know, general public know yes this has got some collagen in and also loss of collagen produces wrinkles and so putting it on the skin might be beneficial. So it's that sort of pseudoscience which is propelling the whole market and also there were small quantities of retinol in some of these products, but formulated in such a way that they were either just very tiny quantities or they weren't being released from the formulation because one of the problems is that if, you know, you could ask well why don't these products all contain all trans-retinoic acids and then wish we know it works, well, the problems is all trans-retinoic acids can in a fair number of people cause side effects, irritation of the skin and the cosmetic company could not afford for a certain percentage of their customers getting skin irritation. They had all sorts of claims on their hands.
Interviewer - Chris Smith
Where do you think this leaves us then, are we going to see lots and lots of companies increasingly trying to sneak ingredients in low level and hope that they choose a cocktail which is underneath the medical radar, so they can still call this a cosmetic, but is just perching on the therapeutic window which you flushed out with a material that you tested.
Interviewee - Chris Griffiths
Well, I think what we're seeing is that there is a move now towards demonstrating efficacy. And, you know, in the past they didn't do that, so all of these companies are doing this now Procter & Gamble, L'Oreal, Boots, and to me I think that is good, it's very good because, it's actually starting to give us good objective evidence as what works and what doesn't work and on the same time there's money now being invested in research in skin ageing and we're learning a lot more about the underlying mechanisms that are consequences of fair investment.
(24:30 - Chemists lend art conservators a hand discovering what the grey crust on a van Gogh is)
Interviewer - Chris Smith
But most dermatologists still agree that the best anti-ageing cream is sun cream. Chris Griffiths was speaking with me from the University of Manchester. Art now, Bibi.
Interviewee - Bibiana Campos-Seijo
This mystic next story is about the work of van Gogh and what some group of preservation experts uncovered when they were doing some preservation work at the museum where they work, there's not very well known at least hadn't seen it before, hadn't seen this painting before, it's a still life called flowers in a blue vase.
Interviewer - Chris Smith
What does this look like, this painting?
Interviewee - Bibiana Campos-Seijo
( Laughs)It's got flowers and they're in a vase. ( laughs)
Interviewer - Chris Smith
Okay, well that now is a down a bit, why are people interested apart from the obvious artistic interest in this particular piece.
Interviewee - Bibiana Campos-Seijo
It has developed a mysterious grey crust on its surface, so
Interviewer - Chris Smith
All over, just in some places?
Interviewee - Bibiana Campos-Seijo
Just certain places, yeah. The experts were actually looking at it and they realized that this grey crust appeared where the cadmium yellow used to appear
Interviewer - Chris Smith
So the cadmium yellow is pigment that gives a certain colour.
Interviewee - Bibiana Campos-Seijo
Yeah, very intense bright yellow. Yes, so w
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