Chemistry World Podcast - May 2010
00:12- Introduction
01:14- Mars meteorite gets a boost of youth
03:38- Going for silver - green plastic production
06:40- Hunter Waite and Tim Griffin chat about using mass spectrometry in space and up volcanoes
14:56- Lead joins the aromatic ring club
17:42- Rousing sleeping sickness research
20:35- Drew Pomerantz, from Schlumberger, on petroleomics and hunting for oil
27:17- Immune cells fight off nanotubes
29:29- Nanoparticles successfully deliver RNA interference in cancer patients
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
Interviewer - Meera Senthilingam
This month, nanoparticles that target cancer cells, using silver to go green in the plastics industry and extreme science with the use of mass spectrometry out in space and in our most active volcanoes. Plus the best way to find oil.
Interviewee - Drew Pomerantz
What we like to do is measure the composition of petroleum, sampled from different places within the reservoir and from looking at differences we observed in the composition, try to understand what has happened to the reservoir in the past or what might be happening to the reservoir now.
Interviewer - Meera Senthilingam
Drew Pomerantz will be explaining how his team at Schlumberger set about doing this later in the program. I'm Meera Senthilingam and also in this May edition of Chemistry World our Bibiana Campos-Seijo, Mike Brown and Matt Wilkinson.
(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)
(01:14 - Mars meteorite gets a boost of youth)
Interviewer - Meera Senthilingam
First up this month, useful meteorites, as a Martian meteorite has been revealed to be a lot younger than we all thought. Is that right Bibi?
Interviewee - Bibiana Campos-Seijo
Yes, this meteorite is the oldest Martian rock found on earth, but is not as old as originally thought. Scientists had dated it at 4.5 billion years old, but it appears to be only 4.09 billion years old.
And so how did they set about revealing this new age?
Interviewee - Bibiana Campos-Seijo
Well, it's a collaboration between scientists at the University of Houston and their colleagues at NASA in Houston as well in the US and while traditionally the age of the meteorite had been calculated by looking at the ratios of long lived isotopes of samarium and neodymium, now these team of researchers have looked at the measures of lutetium and hafnium.
Interviewer - Meera Senthilingam
What about the presence of lutetium and hafnium make them more reliable as elements to be looking at?
Interviewee - Bibiana Campos-Seijo
Samarium and neodymium are present in phosphate minerals, which are relatively reactive and therefore can be easily altered by acidic solutions or shock, but lutetium and hafnium are present in more in minerals that are more resistant to weathering. So the scientists have agreed that that would give a more accurate age for the rock.
Interviewer - Meera Senthilingam
So now they've worked out that this meteorite is younger than we previously thought, but what does this mean about finding out more about Mars?
Interviewee - Bibiana Campos-Seijo
Yeah, they thought this meteorite was part of their primordial crust of Mars, but it was actually formed after a period of very intense volcanic activity. The fact that the meteorite is 4.09 years old and is younger than originally thought, it proves that it formed when Mars was wet and had a very stable magnetic field, which are conditions known to encourage the development of very simple forms of life and these agrees with the original findings of a group of scientists who in 1996 looked at the rock under the microscope and found what looked like fossilised bacteria. So, this new finding seems to support that or confirm that, but the question is very, very difficult to answer. So, but you know, there's information towards confirming the existence of life.
Interviewer - Meera Senthilingam
And now, moving away from the red planet and moving to being green, here on earth, our scientists have identified a more eco-friendly way to produce propylene oxide, now Mike what is propylene oxide currently used for?
Interviewee - Mike Brown
Well, propylene oxide is a very versatile compound, it's a key intermediate in many industrial processes such as creating plastics and things and it can be used in cosmetics, paints, detergents and even in products for your car like antifreeze. Traditional methods for making propylene oxide have produced harmful byproducts like chlorinated waste and acrolein which is a simple unsaturated aldehyde and it's very reactive and toxic to the environment. Other methods that are used also produce carbon dioxide, so these are bad routes to make such a key intermediate because you obviously have to make a lot of it and you're producing lots of toxic byproducts.
Interviewer - Meera Senthilingam
So how have they set about making this more environmentally friendly and who's been working on it?
Interviewee - Mike Brown
So the scientists that've been working on it are collaboration between the US Department of Energy, the Fritz Haber Institute in Berlin and the University of Illinois and they've come up with a new class of nanometer silver catalysts. So they've taken clusters of three silver atoms and reacted them at low temperatures and they found that propylene oxide has been formed with very few byproducts. So, the group have been doing experiments aside of it and they've also had theoreticians helping them to look at the mechanism involved and they found that the open shell electron structure of this silver may be behind the reason why its improved selectivity.
Interviewer - Meera Senthilingam
And in what other ways is this more environmentally friendly?
Interviewee - Mark Brown
Yeah, this new method doesn't produce carbon dioxide and very low levels of other byproducts like chlorinated waste and acrolein, so the environmental implications are so much better. Similar catalysts such as gold catalysts have been studied and with this catalyst, the catalytic cycle is faster and greater by a factor of 4 than the gold catalysts, so the silver catalyst is actually quicker and producing the propylene oxide and its also more environmentally friendly.
Interviewer - Meera Senthilingam
So that's quite an improvement. So what stage is this at now, is it early stage or is this just been discovered, so when they hope to actually be in use in industry.
Interviewee - Mike Brown
At the moment, that's right, it's just on an experimental scale at the moment. But the group is hoping to scale it up to an industrial scale to be used in the future and hopefully this will have an impact on environmental issues in the future. They also are trying to combine catalysts, so that they're bifunctional, which means, basically that they can have one catalyst doing two catalytic steps in a particular process. So that's another area of research that they're thinking of. So maybe in the future, we can have plastic production with one catalyst that moves all the way from the starting material all the way to the plastic at the end.
Interviewer - Meera Senthilingam
Fingers crossed for such a revolution. Thanks Mike.
(06:40 - Hunter Waite and Tim Griffin chat about using mass spectrometry in space and up volcanoes)
Interviewer - Meera Senthilingam
The analytical technique of mass spectrometry has been in use for over 50 years to determine the elemental composition of chosen samples. It identifies elements by ionizing a sample to give charged molecules, the elements within which can then be identified by measuring their mass to charge ratios. It's a common technique in chemistry today, but scientists today are constantly pushing its limits to explore more extreme environments. One such scientist is Hunter Waite from the Southwest Research Institute in San Antonio, Texas and he designed a mass spectrometer to explore the outer realms of our solar system.
Interviewee - Hunter Waite
Well, this mass spectrometer was on the Cassini orbiter, it arrived in 2004 and has been flying around, orbiting Saturn, but passing close by many of the icy satellites and moons of Saturn over the course of the mission, as an example, when we fly close through the upper atmosphere of titan, we find a dense atmosphere and so its usually the brining the instrument or the orbiter in proximity to these moons, where we've been making our measurements.
Interviewer - Meera Senthilingam
What kinds of substances were found then here?
Interviewee - Hunter Waite
Well, Titan's atmosphere is composed largely of molecular nitrogen with a little bit, a couple of percent of methane and the action of solar ultraviolet light on the upper atmosphere, as well as particles from the magnetosphere electrons and ions cause reactions in the upper atmosphere and its created a very rich organic mixtures, hydrocarbons and nitrogen compounds that are much more complex, much higher in density than we ever anticipated. We've seen things that are heavier than molecules such as insulin at those altitudes, so we're creating organic macromolecules, a 1000 kilometers above the surface of Titan just due to the interaction of the sun's ultraviolet light with the upper atmosphere of Titan.
Interviewer - Meera Senthilingam
So given that this was unexpected then was the mass spectrometer designed for this able to cope with what was found or are there now limitations in which future kind of models of this will need to be improved upon in order to accommodate this?
Interviewee - Hunter Waite
Well, this was exploratory type mission; we'd only designed this mass spectrometer to go up to about a 100 Da mass. Many of the molecules were much more complex. If one was to go back, obviously you'd want to go to a higher mass range. In our laboratory we've been working on new techniques that have much higher mass resolution instrumentation and more sensitive as well. A couple of orders of magnitude more sensitive instrumentation as well as higher mass resolution.
Interviewer - Meera Senthilingam
So how would you summarize then given these findings by Titan of organic compounds, how has this improve the understanding of Saturn's atmosphere?
Interviewee - Hunter Waite
I think one of the important things is that in the case of Titan it's a chemistry that's indigenous to Titan itself. It gives us a whole new view of Titan as an abiotic chemical factory in the solar system. It produces organics on the surface that exceed the oil, gas, and coal reserves of the earth by a 10 to 100 times. So there're very effective organic factory in the outer solar system.
Interviewer - Meera Senthilingam
So any potential of shoveling that back to earth to solve our oil supply problems?
Interviewee - Hunter Waite
It would not be impossible, but there would have to be a major investment in transportation systems to make it happen.
Interviewer - Meera Senthilingam
So may be not the answer to our energy problems. That was Hunter Waite from the Southwest Research Institute in Texas. And another scientist hot on Hunter's heels is Tim Griffin, Chief of the chemical analysis branch at NASA whose work using mass spectrometers in space has led to their use in another extreme environment, volcanoes.
Interviewee - Tim Griffin
Yes, we originally used mass spectrometers to help support launch vehicles, to help make sure that we can get vehicles safely into space off the ground. Lot of the gases that we looked for on there are the same as a what are interested in volcanoes. For this reason, we have adapted our equipment and taken our knowledge about being able to take samples from an area and bring it to a mass spectrometer and be able to push the mass spectrometer to its limits and be able to see things that are difficult to see by any other method.
Interviewer - Meera Senthilingam
Now what kinds of gases would you be looking for in terms of a volcanic eruption or an impending volcanic eruption.
Interviewee- Tim Griffin
Hydrogen to some extent, but mainly helium, sulfur oxide and water and carbon oxide. The sulfur dioxide when it gets into the water turns into sulfuric acid, so that is also another thing that can be looked at. The helium is, we believe, is really big precursor for how active the volcano is. Helium is created in the magma, earth's core, and as it becomes closer to eruption times, you can see the increase in the helium.
Interviewer - Meera Senthilingam
And is this the case for all volcanoes or would this have to be adapted to different types of volcanoes.
Interviewee- Tim Griffin
Well there are different types of volcanoes. There are ones that give off more gases than others, the one that just erupted in Iceland had a lot of gas and it was a whole lot of particulate. So, the instrumentation does need to be adapted whatever the particular application is.
Interviewer - Meera Senthilingam
What are the current techniques used to try and predict or monitor gases of volcanoes or predict impending eruptions.
Interviewee- Tim Griffin
The current method for collecting gases are you take an evacuated bottle down into the crater of the volcano and you collect that sample and then you take it back to the lab. Our instrument, we actually can take and do monitor in place. So we can get a better tracking of what's going on with the plume and hopefully some over time trend data.
Interviewer - Meera Senthilingam
What different methods have you used in order to collect your samples?
Interviewee- Tim Griffin
We've carried just around in multiple ways, we've put it on multiple air crafts, and we've put it on the NASA WB57 air craft, which is an air craft that flies up to 50000 feet at a very slow pace. We've also put it on some small personal air craft such as Cessna aircraft and flown it at a very low altitude over volcanoes. Now we've also put it in the back of cars, so we can monitor as we're driving through areas and we've also hand carried it on a sling between two people, so it's proven to be a very versatile instrument.
Interviewer - Meera Senthilingam
And now having taken these samples around the volcanoes in Costa Rica then what were the gases that your spectrometer has picked up.
Interviewee- Tim Griffin
We were able to see a little bit of helium, when we carried it in on the ground and carbon dioxide and sulfur dioxide were the primary gases that we saw and we were able to see and characterize pretty well what happens to the plume.
Interviewer - Meera Senthilingam
This seems like a very promising technique. So how would it operate in the general field of predicting volcanic eruptions then?
Interviewee- Tim Griffin
Well, our technique is pretty new in order to be able to make any predictions about the volcanoes. So a whole system would be incorporated into a suite of instruments that would be able to answer all the questions about the volcano including satellite imaging and satellite instrumentation, to really get a true feel for what's going on. You wouldn't want to do that on every volcano that would be impossible. So you choose your most active or most one's of interest and but that suite of instruments on that, so this would be one part of many instruments that would be used on volcanoes.
Interviewer - Meera Senthilingam
So playing its part in the much needed detection of impending eruptions. That was Tim Griffin from the chemical analysis branch of NASA.
Interviewer - Meera Senthilingam
This is Chemistry World with me Meera Senthilingam. Still to come, the chemical way to find the best oil reserves and the use of nanoparticles to target and kill cancer cells. But first, a new form of aromatic molecule, Matt.
Interviewee - Matt Wilkinson
A team of Japanese researchers have managed to incorporate for the first time a lead atom into an aromatic carbon ring. Masaichi Saito, of Saitama University in Japan took these molecules that contains four carbons and one lead atom and managed to convert it into an aromatic compound. Now for those of you who don't understand what an aromatic compound is, my simple example of one is a benzene ring, which contains six atoms of carbon bonded together with automating single and double carbon-carbon bonds and what's really interesting about it is rather than the bonds being single and double bonds in reality they're all the same length, which indicates the electron density between the double bonds that's shared all the way around the ring and that makes all the bonds much stronger, and gives it some very interesting properties, compared with a normal single and double carbon bonds.
Interviewer - Meera Senthilingam
And now why up and until this point has it been difficult to form an aromatic ring with elements such as lead.
Interviewee- Matt Wilkinson
Well, I think one of the reasons is that it hasn't necessarily been tried, but the other thing is that this group has tried it with a little of steric alkyl around the rings. They will have six carbon rings around them anyway and on the lead itself, what they've done is it originally had two phenol groups on there and they've swapped those for two lithium atoms or lithium ions I should say, and that gives the lead a negative charge, which can be then be delocalized around the ring, so its really a case of finding the right system to get this to work.
Interviewer - Meera Senthilingam
And now will this be possible with similar elements.
Interviewee - Matt Wilkinson
Well, there are other examples where you can include other elements in these types of rings. I think this is one of the heaviest that's been included, so far and the problem with that is it has atoms get bigger or elements get bigger, their electron shells become more diffuse, so there's less overlap between a really big electron shelf and say a lead atom with say one from carbon, then there would be of two carbon atoms where they're the same size, so the problems becomes in having the correct overlap between those orbitals. So you might get bigger atoms being included but there will eventually become a limit where the sharing of those electrons becomes too small for it to really begin to count to aromaticizer.
Interviewer - Meera Senthilingam
Now having put in this effort to these aromatic molecules, what are the benefits or what can be done now they've made these.
Interviewee- Matt Wilkinson
Well, I think in the first case, this really is a chemical curiosity, its one of these things we don't see everyday. The researchers themselves believe that there may be some applications in catalysis because they do mimic a type of molecule called carbene that has found lots of use in various different catalytic reactions, but how far this will move down at this stage is unknown.
Interviewer - Meera Senthilingam
And well moving over to some more biological aspects of chemistry and that's sleeping sickness, where a potential oral drug for sleeping sickness could soon be on the horizon Bibiana Campos-Seijo.
Interviewee- Bibiana Campos-Seijo
Yes, African sleeping sickness is neglected disease that affects more than 50000 people over the world and if left untreated, its almost always fatal. So a collaboration between researchers at the University of Dundee and the University of York, both in the UK have screened more than 60000 small molecules for a potential lead to try to treat the disease.
Interviewer - Meera Senthilingam
Now what are the limits of current treatments against sleeping sickness?
Interviewee- Bibiana Campos-Seijo
While the treatments at the moment are not very good at all, first of all they need to be administered by injections and one of them is a bit of Russian roulette because one in 20 patients that take melarsoprol are killed and those that survive have very nasty side effects because it contains arsenic. The other available treatment, a fluoromethane requires although less toxic several visits to the hospital and you have to have intravenous infusions for a number of hours during that period of two weeks. So, obviously not something that you will be able to do very easily in the developing world for example.
Interviewer - Meera Senthilingam
So, how would this new molecule go about inhibiting the disease?
Interviewee- Bibiana Campos-Seijo
The researchers have identified a new target protein called, NMT or N myristoyltransferase which is found in the parasites that cause the disease through Trypanosoma brucei parasites. NMT is an enzyme that attaches fatty acid chains to about 60 proteins within the parasite; therefore it controls the protein's localization, stability and function, so by attacking NMT you could potentially impair the growth of the parasite.
Interviewer - Meera Senthilingam
That sounds like a very good target indeed. So what stages is that now, what's all the potentials for it to be used as a drug.
Interviewee- Bibiana Campos-Seijo
They have done in vitro cell culture studies and they have also done in vivo technical studies in mice and they administer very high doses, but they were cured off the diseases within about 3 days, but we're talking about the bloodstream parasite, but with sleeping sickness, you have two stages in the disease, the first one is when the fly bites the host and releases the parasite into the bloodstream. From that it moves onto the central nervous system, where it disrupts the host's sleeping patterns and causes dementia, comas, and potentially death. At the moment, the scientists have only been able to attack the parasite while it is in the bloodstream, but not when it is in the CNS. There's obviously the issue of getting the drug through the blood brain barrier of course.
Interviewer - Meera Senthilingam
And so is that potentially what this molecule could hopefully do?
Interviewee- Bibiana Campos-Seijo
We continue to do studies and also they will be looking at the toxicity and also the potential for the parasite developing resistance.
Interviewer - Meera Senthilingam
Thank you Bibi. Oil - as much as we're trying globally to wean ourselves off it, we still need it a lot and demands are fast outweighing the supply. So how can scientists set about exploring our reserves to best resources of oil and also the best way to extract it without changing its composition? Well, one person whose job it is to come up with this is Drew Pomerantz, research scientists at oil field service company, Schlumberger.
Interviewee- Drew Pomerantz
So, petroleum is one of the most complex naturally occurring mixture and its out job to try to understand what is the composition of petroleum and to use that information to figure out where in a reservoir oil might be located, how much oil might be there and what would be the most efficient way to get that oil out of the ground.
Interviewer - Meera Senthilingam
So what are the components of petroleum that you look into and how do you look into them?
Interviewee- Drew Pomerantz
The most abundant component in petroleum is usually alkanes, but in terms of finding oil and figuring out how to produce it, you need to think not only about the composition of oil but its functions. So for example oil has some resistance to flow, some viscosity, it has some propensity to separate into different phases, for example, a solid phase separates out that is likely to clog out your flow lines or even worse clog out the pore space in your reservoir rocks that makes a really difficult to get the oil out of the ground. To understand things like viscosity and what people refer to as flow assurances is breaking into phases, now you have to look at more than just the most abundant components of the oil. For example, it is the highest molecular rate, the highest boiling point components of oil referred to as Asphaltenes, this is the same thing that you make roads out of and then you make roofing tar of, its found in petroleum and that fraction really contributes to the viscosity of the oil and it really contributes to the propensity of the oil to separate out asphaltene-rich solid phase that could clog your pipes or clog your rocks.
Interviewer - Meera Senthilingam
So essentially, you want to try and find the places or the sources of oil that wouldn't have that present.
Interviewee- Drew Pomerantz
Exactly, before you can figure out what you can do to remediate it, for example, as people begin looking in deeper and deeper waters? To produce oil one of things they encountered is that they now have to pipe their oil through relatively cold waters in order to go from the reservoir to the shore. At those temperatures, there can be waxes that precipitate out and one of the things we like to know is first of all, can we predict the wax onset temperature, when this problem will occur, then can we come up with the most economic way to remediate against it, that could be heating the pipes or could we be adding the diluents or some sort of solvent to the crude oil that would better stabilize the waxes.
Interviewer - Meera Senthilingam
Now as well as temperatures, what other factors can play a role in changing the composition of the oil.
Interviewee- Drew Pomerantz
When oil is produced from the ground to the surface, the two main changes that occur are the temperature drops and the pressure drops and each of those can cause a problem. For example, you could imagine that there is some components that are in the gas phase at the high temperature reservoir but they condense when you drop the temperature, when you produce the oil. At the same time, you could imagine there are some components that are in the liquid phase when the oil is at high pressure in the reservoir, but they volatilize when you drop the pressure to get the surface, so changes can occur both ways in liquids going to gases, gases going to liquid or supercritical fluids going to either. You must understand which of these processes will occur in order to figure out most efficient way to capture the oil. The plumbing that you put on the surface is going to be different based on whether you expect to produce mainly gas or you expect to produce mainly liquids.
Interviewer - Meera Senthilingam
So, your role is to find out where now you can extract and how you could extract oil from the ground then. So how would you target the places that you could feasibly extract oil or petroleum?
Interviewee- Drew Pomerantz
One thing that the industry is only really now only beginning to appreciate is that even within a particular reservoir, the composition of petroleum can vary greatly, oil being complicate mixture of many components will naturally settle out into different compositions at different places in the reservoir. A typical example is the relatively light components of the petroleum, for example, methane, ethane being at low densities they raise to the top, they're concentrated near the top of the reservoir. On the other hand, the high dense components like asphaltenes are found concentrated near the bottom of the reservoir. A reservoir may even today, be actively charged or actively filled with oil or gas or the oil that's in there may be actively being altered by the presence of bacteria. So, if you have all of these processes that p
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