Chemistry World Podcast - June 2010
00:12- Introduction
01:23- Chemical secrets of dinobird revealed
04:35- Frosty asteroid surprises astronomers
07:45- Mohan Srinivasarao, Georgia Intitute of Technology, US, on why butterfly wings appear coloured
14:38- Natural artificial muscles
17:00- Blood type testing for a few pence
19:30- Dianna Bowles, University of York, UK, tells us about current attempts to increase supplies of antimalarial medication
26:38- All clear for e-paper
29:53- Setting traps for uranium
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
Interviewer - Chris Smith
This month, bright colours but without the pigments, how the wings of a butterfly could make your mobile phone much brighter than it was before. Also how a piece of paper can tell a person's blood group in just seconds and why it's also time to wind your watches back 4.5 billion years.
Interviewee - Phillip Broadwith
The current theories of the solar systems formation say that when earth was formed it was too hot to have any water on it. The water must have arrived after the planet had cooled, proposed sources of that are big icy things like comet but if you look at the hydrogen-deuterium isotope ratio in comets it doesn't match up with the hydrogen-deuterium isotope ratio of the water on earth, so there must be some other sources to account for that difference.
Interviewer - Chris Smith
Phillip Broadwithhas the solution to that watery mystery in the form of a frosty asteroid and it's on its way, that's the answer not the asteroid. Hello, I'm Chris Smith and also in this the June edition of the Chemistry World podcast Mike Brown, Phillip Broadwidth and Bibiana Campos-Seijo.
(Promo)
The Chemistry World Podcast is brought to you by the Royal Society of Chemistry. Look us up online at chemistryworld dot org.
(End Promo)
Interviewer - Chris Smith
First up this month, the chemical makeup of a dinosaur, Mike.
Interviewee - Mike Brown
So, a collaboration scientist from Stanford University, the University of Pennsylvania an the University of Manchester in the UK have been studying archaeopteryx which is a dinosaur specimen that is basically the link between the birds and the dinosaurs, say it's got bird character and dinosaur character, a reptile character. The team had been looking at the fossil specimen of archaeopteryx using a technique called synchrotron rapid scanning x-ray fluorescence which is a technique that identifies a chemical structure at very, very low concentrations.
So this is where you shine synchrotronic in other words x-ray type beams at a surface and various atoms embedded in that surface then fluoresce or glow with light of very specific wavelength which you can pickup and then we should decode what chemicals are on that surface or in.
Interviewee - Mike Brown
Yeah, that's right.
Interviewer - Chris Smith
And how is this helpful to understand what is going on in a fossil?
Interviewee - Mike Brown
Until now people have thought that fossils are just imprints of bones and the structure in this instance archaeopteryx but they've been looking very closely at the fossils and have found that in actual fact this remnants of bone and protein tissue left, so they are not just imprints, they're actually tissue and structure. So, what they have actually found is that there are traces of sulphur and phosphorous on the fossil.
Interviewer - Chris Smith
Presumably the sulphur is coming from proteins and the phosphorous is going to be maybe bits of DNA but probably bone?
Interviewee - Mike Brown
Yeah, that's right, so sulphur is found in cysteine which is in carotene which is a tough fibrous structure of protein in hair and nails. And in birds it's found in the feather shorts, the thick bit at the bottom and what they found is that the sulphur concentration in archaeopteryx is very, very similar, very good correlation to modern birds, now a days like canaries and things like that. And the phosphorous that's present in the sample is also very, very similar to the concentrations of phosphorous in bone of modern birds as well. So this is direct correlation between dinosaur millions of years ago and modern birds which is really exciting.
Interviewer - Chris Smith
Which reinforces the notion that birds are the closest living relative to dinosaurs have today? So what are they going to do now, that they've got his interesting observation, where they're going next with it?
Interviewee - Mike Brown
The plan at the moment is to study other dinosaur fossils so and there are quite a few specimens of archaeopteryx in Germany and they're going to confirm their data by studying other specimens of the fossil, then they're going to move on to other specimens of other fossils, other dinosaurs to see whether we can find out whether there is any residual tissue or bone left in the fossils that they thought were imprints.
Interviewer - Chris Smith
That's really interesting stuff, thank you very much Mike. Let's go from something that we think was responsible for wiping out the dinosaurs, an asteroid to present research on asteroids. Now so tell us about some asteroids and their sugary coating.
Interviewee - Phillip Broadwith
Well, Chris, this particular asteroid 24 Themis it's in the main asteroid belt and it's been found to have a very thin coating of ice all over the surface. It's not usual to find actual ice on these kinds of objects, normally water or ice would sublime at the temperature and pressures around these asteroids.
Interviewer - Chris Smith
Just orientate me in terms of the solar systems and the like kind of things, where is this body, and how big is it; it's a big asteroid, isn't it?
Interviewee - Phillip Broadwith
Yeah, it's a really big asteroid, that's how we can sort of see it using these telescopes, we're actually talking about a family of asteroids, there are in the main asteroid belt; so between Jupiter and Mars and what's been seen in other members of this family is that they have comet-like tails. So that kind of tells us that there's ice on them but they're too small to study properly with the telescopes that we've got, you got to look at the big brother if you like which is several kilometres across and see whether there is ice on that.
Interviewer - Chris Smith
So, how are they accounting for the fact that there is a sheen of ice around the outside of this big body, is that ice coming from inside somehow getting on to the surface?
Interviewee - Phillip Broadwith
So, what these guys did is that they took infrared spectra, they looked at, there's a particular absorption in the spectrum that indicates that there's water of some kind present. They've compared that spectrum with known hydrated minerals to see if the water is trapped within a mineral structure, it's not and then they've used some spectrum modelling to work out exactly what kind of ice they're looking at. Is it small bits or big bits and what they've seen is this it's very thin coating of ice so that's a bit of a conundrum. So what they're suggesting is that somehow ice that subliming from a deeper store within the asteroid is then condensing on the outside because of the very large gravity of this thing; it's bigger than most than a lot of other asteroids, the ice can't quite escape when it's subliming.
Interviewer - Chris Smith
And because the asteroid belt is basically a planetary rubbish dump, its material that would've formed a planet didn't quite get there, it's the building blocks of rubble left over from the building of our solar systems 4.5 billion years ago. Probably this is therefore really informative about the kind of stuff that went in to forming planets and tells us a bit about whether water came from that we find on planets like earth now.
Interviewee - Phillip Broadwith
Exactly that Chris, the current theories of the solar system's formation say that when earth was formed it was too hot to have any water on it; it was a big ball of molten rock. The water must have arrived after the planet had cooled, proposed sources of that are big icy things like comets, but if you look at the hydrogen-deuterium isotope ratio in comets it doesn't match up with the hydrogen-deuterium isotope ratio of the water on earth so there must be some other sources to account for that difference.
Interviewer - Chris Smith
So those asteroids could hold the key to the answer, thank you Phil and incidentally if you would like to read a bit more about that asteroid work, which is being carried out by Humberto Campins, Andrew Rivkin and Joshua Emery you can look up Phil's report which is called frosty asteroid surprises astronomers and it's on the Chemistry World web site at chemistryworld.org.
Interviewer - Chris Smith
Now many of you are probably acquainted with the adage that butterfly flaps its wings in South America and it causes a hurricane somewhere else in the world that's Chaos theory but I bet you haven't had the version that ends in and creates a much better screen for your laptop.
Interviewee - Mohan Srinivasarao
My name is Mohan Srinivasarao, I am a professor at Georgia Institute of technology. We're trying to understand what are all the different mechanisms that exist to produce a visual appearance and in other words what is the colour of the wings of a bird or the wings of a butterfly and things of that sort and what are all the various ways you can produce colour and how does nature get it done.
Interviewer - Chris Smith
Because many people would believe if you look at things around us in the real world that most of those are pigments. That's actually true is it?
Interviewee - Mohan Srinivasarao
Right, there's a lot of pigmented colours obviously lots of plants have pigmented colours although there are a few exceptions where plant colours have structurally based colours by that I mean some kind of a structure that interacts with light to produce the appearance that you happen to see. And so we are particularly interested in things in butterflies or beetles or birds that produce colour not necessarily because of pigments but because of a variety of structural motives that exist.
Interviewer - Chris Smith
The wavelength of light being what it is, those structural colours must be being produced by arrangements of molecules down at nanometre scales. Do you think it's easy personally, to understand how this works but beagle so to copy it?
Interviewee - Mohan Srinivasarao
Copying I think is the easier part because we don't have to arrange the molecules quite the same way as it is done in the wings of a butterfly you just need a structure that mimics that, if I am thinking about say a blue of a blue morpho.
Interviewer - Chris Smith
Which is a butterfly, isn't it?
Interviewee - Mohan Srinivasarao
This is a butterfly, the structural features that produces that colour is absolutely fantastic on multiple length scales; however, in order for me to create a blue that looks more or less like a morpho butterfly blue, I don't exactly have to have the same architecture the butterfly created to produce that blue.
Interviewer - Chris Smith
So, if one looks at a blue morpho butterfly and you could zoom in on the wing surface, what's there to make the colour that we see?
Interviewee - Mohan Srinivasarao
The wings are essentially made up of chitin and chitin is a complex bio molecule however what is more important for the production of the colour is there is a Christmas tree-like structure that is produced and the spacing between certain shape of that Christmas-tree like object that is on the order of the wavelength of light, or a little less than that. It is very intricate and that is what allows the blue morpho to have a colour it does. The beauty of the structure of scales is in the organization of chitin what various structural elements there are is just absolutely fantastic; the variety is just astounding and I don't think we can with all the photo lithography advances I don't believe that we can exactly make what the butterfly does.
Interviewer - Chris Smith
So, are people actually trying to copy this and what they have in mind doing, I mean what could you do with an understanding of this technology?
Interviewee - Mohan Srinivasarao
Right, the idea is not to have any dyes and pigments, you know, in many cases dyes have been associated with variety of problems with disease in some cases. And so the attraction is to produce a colour or produce an appearance of a particular colour without having the pigments involved in it. The second thing is, is it possible that we could understand what is it that creates this beautiful structures in the wings and can we replicate it in a very large length scale over centimetres for example or even several inches if you will without really having to have complex lithographic processes to do that. And so the question is is it possible that somehow we could produce the colour that we want by understanding how the butterflies do it and can we do it rather in an elegant fashion just as elegantly as a butterfly does?
Interviewer - Chris Smith
With an eye on climate change, global warming and making things more efficient though, one thing that I have noticed is that many of these things like butterflies that do use structural colour, they don't' come equipped with their own light source but they nonetheless look incredibly bright, so can we take something away from this in terms of how they do that, how they get so reflective and use that to make much better or more efficient use of energy in the world around us?.
Interviewee - Mohan Srinivasarao
I think that's entirely possible and in fact I think there was a company formed in Massachusetts number of a years ago and I am told that company has been bought out by Qualcomm for mobile phone displays, so for example right now your computer screens are all backlit, meaning there's a light behind the computer screen and that takes away a lot of your energy and your computer screen of course is particularly useless if you're sitting outside in the sun, but the butterflies on the other hand are fantastic. It is that attraction I think that led Qualcomm to buy this company out and the idea was to create structures just like the butterfly does and to be able to move those structures fairly quickly to produce various colours because after all by moving those structures and changing the periodic nature of the material and that changes the reflectivity and this would be a low power consuming but incredibly bright display.
Interviewer - Chris Smith
How long do you think it will be before we start to realize the potential of the things that you've been talking about?
Interviewee - Mohan Srinivasarao
Well, I think Qualcomm already has a display out in the market, although I haven't seen it and I would suspect within the next 5 to 10 years, we will see these things out in the market place, I mean they are already Procter & Gamble has their toothpaste displays that have structural colour in them, other places for example, currencies of certain countries have an interference security device. So we will see them increasingly I think.
Interviewer - Chris Smith
So some day soon, you'll finally be able to see what's actually on the screen of your mobile phone on a sunny day. That was structural colourist Mohan Srinivasarao and he is based at Georgia Tech in the US.
Interviewer - Chris Smith
This is Chemistry World with me, Chris Smith still to come how a piece of paper can tell a person's blood group but first Bibi researchers in Canada and the US are flexing their artificial muscles this month, tell us about this.
Interviewee- Bibiana Campos-Seijo
A lot of research has gone into developing synthetic elastomers to mimic the elastic properties of a muscle tissue for simple medical applications. But there are several limitations associated with this. the very first one is that very often these materials are, they're not identified by the immune system of the host's body and therefore have attacked and rejected. And the other one is that the systems, these materials cannot help with tissue repair or regeneration, therefore trying to synthesize or trying to prepare artificial muscle tissue using protein is an alternative that seems to have some basis.
Interviewer - Chris Smith
How are researchers trying to pursue that?
Interviewee- Bibiana Campos-Seijo
Researchers at the University of British Columbia in Vancouver in Canada together with co-workers at Virginia Polytechnic Institute and State University in the US are working to try to replicate the properties of titin which is a muscle protein. It actually is very interesting because it's the largest single polypeptide in nature and is responsible for the passive elastic properties of muscle.
Interviewer - Chris Smith
It's one of the structural proteins isn't it? It helps the muscle to range where it puts the other fibres like the actin and the myosin that do the contraction, so how have they actually built this protein?
Interviewee- Bibiana Campos-Seijo
They've engineered biomaterials that consist of globular proteins. They are the molecular springs and they're derived from streptococcus bacteria together with amino acid sequences derived from resilin which is an elastomeric protein. They have used genetically modified Escherichia coli bacteria to express these proteins and then they used a photochemical reaction to crosslink them and this resulted in a gel-like material that has the desired properties which are the toughness and the elasticity of the natural muscle proteins.
Interviewer - Chris Smith
Have they actually demonstrated it can be used yet though or is it just at the experimental stage?
Interviewee - Bibiana Campos-Seijo
It is at the experimental state and they're hoping to use it in tissue engineering as scaffolding matrix for artificial muscle.
Interviewer - Chris Smith
Well, terrific news and may hope well it would be too long, because obviously muscles and rebuilding them is important, especially I suppose we possibly try that for micro machines and things as well.
Interviewer - Chris Smith
Well, look here's something that probably will have a tangible use much use much sooner and is probably closer to being realized and it might be in news right now, Mike tell us about this new way of using a piece of paper to work out what blood group someone is having.
Interviewee- Mike Brown
Well, researchers at Monash University in Australia have devised a cheap paper test to quickly identify your blood type.
Interviewer - Chris Smith
Well, that sounds fantastic, obviously identifying what blood group someone is, is very important, so we give the recipient the right blood, so they don't have a transfusion reaction, but how does this work?
Interviewee - Mike Brown
Well, researchers have taken a piece of paper and they put a micro fluid circuit on it containing antibodies at different parts of the circuit; antigens which are chemical markers on the surface of the red blood cells will interact with the antibodies, different antibodies. So, depending on where you put the blood on the circuit the blood where you've spread out because it's not reacting with an antibody or it will agglutinate because it is reacting, so you've got a very visual representation as to which antibodies are affecting your blood and therefore you can workout which blood type you're.
Interviewer - Chris Smith
And it does all the blood groups, what about Rhesus D as well as that's important in childbirth, I think? Does this do that one too?
Interviewee- Mike Brown
Yes it does, yeah; it's got a separate section with the antibody for Rhesus as well.
Interviewer - Chris Smith
And who is this useful for, because obviously we are well developed blood services in countries like this one and where this may be less useful, because we already know how to do this where we have machines to do it for us, so where are they targeting this at.
Interviewee- Mike Brown
The researchers hope that the piece of paper, that the test will be very useful for third-world countries where you don't need specifically someone trained or a doctor or a nurse to do the procedure and you basically take a blood sample and you spot it on the different sections of the paper. So you can have an unskilled person doing it in the third world where they don't have electricity and they don't have access to other ways of testing blood.
Interviewer - Chris Smith
More importantly, what does it cost?
Interviewee- Mike Brown
It's very, very cheap. In theory, you can just send hundreds of thousands of these out and basically they'll be equipped with these tests, so they can find out very, very quickly what blood type someone is and therefore give them the right blood to help save their life.
Interviewer- Chris Smith
Sounds like a fantastic breakthrough, might look like it will make a massive impact especially in developing countries. Thank you Mike.
Interviewer- Chris Smith
Well on the subject of developing countries, many of them have a serious problem with malaria. In fact, there are up to 500 million cases of malaria, every year, 3 million of them fatal and the majority of those fatalities happening in children. The problem is made worse by the fact that the malaria parasite has become resistant to many of the standard drugs that are normally used to treat and prevent the disease. But there is one drug that's showing considerable promise, Dianna Bowles.
Interviewee- Dianna Bowles
The world is keen to eradicate malaria completely and control measures are being substantially scaled up and part of this whole movement to eradicate malaria includes the increased use of a particular therapy, which is called artemisinin combination therapy and this is known to be the most effective treatment of malaria. The problem that the world is facing is that the sole source of artemisinin is a medicinal plant, Artemisia annua. It's found wild in China and in fact many of the leads of the preparation of artemisinin and are actually collected from wild plants still in China. Elsewhere, in the world, it's grown by thousands upon thousands of small scale farmers, throughout Africa, India, China as well and also Vietnam and many other countries, in fact in the developing world.
Interviewer- Chris Smith
So, there's potentially a supply problem.
Interviewee- Dianna Bowles
There is very little plant breeding that has been carried out on this wild medicinal plant.
Interviewer- Chris Smith
How much artemisinin can one get from one plant then?
Interviewee- Dianna Bowles
Well, a typical yield is thought to be about 0.4 to 0.6% of the dry weight of the plant. Obviously, the amount that you get from a plant depends on the biomass, the extent of the leaves of the plant. But in total, it's thought that these days, you need to really plant about 20,000 hectares of Artemisia.
Interviewee- Chris Smith
So, obviously one solution would be to find a way to either bulk up the production by growing more plants or to do something to the plant, so that they're a lot more effective at producing the agent or it's produced in a form which is easier to extract from the plant.
Interviewee- Dianna Bowles
That's right. The difficulty with growing more Artemisia is that it's not a robust crop, the lack of breeding Artemisia has led to really the lack of a robust crop, and even when one is planting large acreages many of those plants fail. And so the difficulty is that those never are consistent amounts of artemisinin on the market to actually ensure a robust supply for ACT. There is getting to be certainly in this year 2010-2011 and increasing shortage of the actual amount of artemisinin and it actually exists and available. But in addition, ACTs are expensive compared to other treatments. Even though artemisinin is the only compound currently that is effective against all forms of the parasite that causes the disease.
Interviewer - Chris Smith
So what can we do about it?
Interviewee- Dianna Bowles
Well, I think there's two issues, one is that there is a massive new funding or financing mechanism to make ACTs cheaper and this reduces the ACT price. It's called AMFm and the AMFm initiative reduces ACT price to equivalent to monitor other substance of drugs. The aim is to increase therefore the ACT availability and therefore more artemisinin will be required and therefore we have a window of opportunity from the funding to actually get more artemisinin and ACTs in the market and we have to therefore improve the quality of the plant to be a crop, i.e., to increase the amount of artemisinin that each plant produces to improve the extraction techniques to ensure that we can increase the efficiency of those and also to develop new plant varieties that have both increased yield of artemisinin and also are robust in the different growing regions of the world, where farmers are growing.
Interviewer - Chris Smith
Do we know how artemisinin plants actually produce the agents?
Interviewee- Dianna Bowles
We have a lot of information about that and certainly the funding from the Bill and Melinda Gates Foundation and the projects that I co-direct with professor, Ingram here at York. What we have really managed to do over the last four years is gain a huge amount of data both at the genetic level and the molecular level and at the chemical level of these plants. We know that artemisinin is made in secretory glands that exist on the surface of the plant on the aerial parts of the plant, on the leaves mainly. And these secretory glands are like microfactories, they're called tricones and they're found on all plants and they're specialized microfactories for many compounds, particularly terpenoids and in fact they play a major role in producing compounds for that to the entire flavour and fragrance industry.
Interviewer - Chris Smith
So, does this mean that we could copy them and put them in a plant that is a bit more robust, or one further step down the line, can we just take the genes that are orchestrating the synthetic process and put them into something which is a lot more cooperative, yeasts or bacteria or something.
Interviewee- Dianna Bowles
That's also a very interesting comment because the Bill and Melinda Gates Foundation are funding two strategies really to make sure that the artemisinin supply is improved. One is our project which looks at plants and is the only sources of Artemisin currently and before they funded our project, they actually also funded a team in the Sates to do exactly as you were saying, which is to list the genetic machinery, out of the plant and put into a fermenter and start industrial fermentation. This project is also ongoing but I think one of the important things for everyone to remember is that really the amount of artemisinin that's required if the AMFM initiative is to work to eradicate malaria. We'll require multiple approaches to producing artemisinin and in terms of the plant, it's been calculated by many, many different groups, at least 60 to 70 percent of the artemisinin required for the next 10 years will have to come from plants, whether or not, the industrial fermentation route is successful.
Interviewer - Chris Smith
Dianna Bowles, s
No comments yet