Chemistry World podcast - July 2013


Audio Files

The Chemistry World podcast is sponsored by Waters – world leaders in innovative analytical science solutions. Visit waters.com for more information.

1.33 The surfaces of lava stones from Mount Etna, in Sicily, may be leaching manganese into the environment - Misdiagnosed manganism near Mount Etna?

4.24 US researchers have discovered a way to selectively isolate and recover gold from raw materials using a simple sugar derived from corn starch - Sugar solution to toxic gold recovery

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6.23 Hagan Bayley explains how 3D printing offers the control he needs for scientific discovery - Press P to print

13.32 Historical parchment scrolls that have become too fragile to be unrolled could soon be read again thanks to an X-ray imaging technique - Digitally unrolling historical scrolls

16.16 Scientists in Canada have made a super-strong cell membrane adhesive and used it to stick red blood cells together - Super Glue for cells

17.51 Chad Mirkin, Chemistry World Entrepreneur of the Year 2013, explains how programmable atom equivalents, made from DNA nanoparticles, can herald a range of new technologies including rapid medical diagnostic tools  - No small success

26.14 A catalyst made from soybeans could overcome a major barrier to cheap hydrogen fuel - Soybean catalyst for hydrogen evolution

28.32 Researchers in China have discovered a new method of male contraception: a quick injection of gold nanorods into the testes, followed by a 10 minute dose of infrared light - Will nanorods be the next big male contraceptive idea?

32.02 Trivia - Who had a busy day with the periodic table 205 years ago?

Full transcript

Interviewer - Chris Smith

This month: how 3D printing techniques are enabling scientists to produce artificial tissues that can even send, receive and respond to external signals.

Interviewee – Hagan Bayley

We're able to put engineered membrane channels and pores into that bilayer and get our aqueous compartments to communicate with each other and to communicate with the outside world and communication between cells are really the basis of how tissues would work

Interviewer - Chris Smith

Also, a way to spot sepsis in record time.

Interviewee – Chad Mirkin

You ultimately have to go on antibiotics and it’s important to know what organisms you're infected with to select the right types of antibiotics. Current tests take about 3 days. This test takes less than two hours. It’s a game changer in the whole medical field.

Interviewer - Chris Smith

And a contraceptive nanorod laser combo that can warm testicles temporarily to stop sperm production. Fancy volunteering? Well that's all to come in this Chemistry World podcast sponsored by Waters the World Leaders in Innovative Analytical Science Solutions. Visit waters.com for more information.

(1:33 - The surfaces of lava stones from Mount Etna, in Sicily, may be leaching manganese into the environment -Misdiagnosed manganism near Mount Etna?)

Interviewer - Chris Smith

Hello, I'm Chris Smith and also with us for this the July 2013 edition of Chemistry World are Neil Withers, Phil Robinson, and Emma Stoye who has an eruptive story to start us off.

Interviewee - Emma Stoye

This is about how manganese from rocks erupted out of Mount Etna in Sicily might be contaminating water supplies and causing cases of poisoning there that have very similar symptoms to Parkinson's disease. This all really arose when they realized that cases of Parkinson's were being diagnosed around mount Etna in much higher instances than elsewhere. Then a couple of years ago, they had a look at the water from the wells around Mount Etna that serves one and a half million people and they found that they did have high levels of certain elements, in particular manganese. So this was about fifty times higher than the recommended safe level of manganese.

Interviewer - Chris Smith

And does manganese cause a Parkinson's like disorder?

Interviewee - Emma Stoye

Yes, so it doesn't cause Parkinson's but manganese poisoning or manganism is similar to Parkinson's in the symptoms you get, so tremors and things like that. But it was a little bit of a mystery really why the water around Mount Etna had this manganese in it. They had looked at the rocks before, the rocks from the lava that comes out of the volcano and they hadn't really found they had higher levels of manganese at all.

Interviewer - Chris Smith

So where was it coming from then?

Interviewee - Emma Stoye

So this is where a group led by Antonino Gulino at the University of Catania. They started to take a closer look at these rocks. They used a technique called x-ray photoelectron spectroscopy to just survey the surface of these rocks. So this is firing x-rays at the rocks and measuring the electrons that come off, but from the very surface layers, just down to depth of 10 nanometers. What they actually found was different to what people have found before. They found that the concentrations of manganese on the surface of these rocks was about twice as much as what they're finding throughout the bulk of the rock and obviously the surface is what the water is going to come into contact with when it’s washing over the rocks, so that might be how the manganese is getting from the rocks into the ground water.

Interviewer - Chris Smith

Interesting finding, but if there were volcanoes all over the world, which there are, potentially there could be the same risk elsewhere, so people should be checking the water.

Interviewee - Emma Stoye

There could be same risks elsewhere and I think people do check the water and now that's something that can be followed on from if you're checking the water you can then think about where these things are coming from and it’s just another way of surveying the rocks and looking at exactly what's coming out of these things.

(4:24 - US researchers have discovered a way to selectively isolate and recover gold from raw materials using a simple sugar derived from corn starch - Sugar solution to toxic gold recovery)

Interviewer - Chris Smith

Thank you Emma and Neil from manganese to gold, what's the story here?

Interviewee - Neil Withers

Well, a team of US scientists have discovered a way to isolate and recover gold from solution using a material derived from corn starch, cyclodextrin, rather than the more nasty cyanide that's been used much more widely.

Interviewer - Chris Smith

How did they discover this?

Interviewee - Neil Withers

Well interestingly, it was entirely a serendipitous discovery. The team of Fraser Stoddart at Northwestern University were trying to make metal organic framework material, so we have a metal ion with a sort of organic linker in between which made these very open framework materials. But when they mixed the cyclodextrin with gold bromide ions instead of getting a open framework, they got very small, very thin needles, which are not three dimensional, but almost one dimensional, and when they added a reductant, sodium metabisulfite, they got pure gold.

Interviewer - Chris Smith

Wow! They were trying to make something which was going to be one of these open framework type things and instead discovered they've made a sieve for gold atoms.

Interviewee - Neil Withers

It’s not exactly a sieve. So, what happens is the cyclodextrin is quite a large macrocycle, a ring of smaller rings, and that's just the right size to fit one of these gold bromide ions inside the hole and they kind of stack up like sets of tea cups and apples, if you like, they all managed to stack together and that's what forms these long needles rather than the extended three dimensional solid.

Interviewer - Chris Smith

Do you often need to clean up gold bromide, this doesn't sound like a particularly common chemical?

Interviewee - Neil Withers

Not really but if you were to try and isolate gold from a bunch of recycled materials then you could add hydrobromic acid and then you might end up with gold bromide. This would be a really efficient way of getting it out a solution using a very clean, and environmentally friendly reagent, rather than other nasty things.

(6:23 - Hagan Bayley explains how 3D printing offers the control he needs for scientific discovery - Press P to print)

Interviewer - Chris Smith

Neil Withers. In need of a new organ or tissue, well this man might be able to help. He'll print you one.

Interviewee - Hagan Bayley

My name is Hagan Bayley and I'm the Professor of Chemical Biology at Oxford University. 3D printing is a technology that's been very much in the news. It’s been used to build everything from violins, pieces of bone and so on using a molten plastic or some metal powder and you end up with a 3D object. So, rather than making a statue like Michelangelo, taking a block of material and chipping away at it and seeing what's left, you actually build up the material layer by layer, so you don't lose any precious metal in building it, but it also is a very accurate and precise way of making an object as well.

Interviewer - Chris Smith

What about the actual physical process of printing. What does that and have we had to invent new things to do that or did we already bizarrely enough have the tools for the job?

Interviewee - Hagan Bayley

Well, that will depend on the material. So if you're printing a plastic, you will have a model that sends out molten plastic droplets or plastic droplets that can be later polymerized by light for example but if you're doing what we're doing, printing aqueous droplets, which resemble cells, this is a very different matter, you need a very different type of printing head, so we have to devise a printer from first principles.

Interviewer - Chris Smith

What's the raison d’être behind the work you're doing?

Interviewee - Hagan Bayley

Well, this time the advantage that we're not dealing with living cells, so obviously living cells have to be kept alive. So, if you print a piece of tissue that's more than say several millimeters across, you'll have to get nutrients and oxygen to the cells in the center of that tissue.  So, we are just printing very simple compartments that may contain a limited number of chemicals or biochemicals that can still perform a function. But we're not dealing with living cells which might be dangerous because they might proliferate in the body and we are not having to keep them alive with nutrients.  This simplicity has certain advantages in that regard.

Interviewer - Chris Smith

Are you making these aqueous droplets from the same sorts of chemicals that a cell will be made of, they're just devoid of the other things you'd find in a living cell?

Interviewee - Hagan Bayley

Yes, these aqueous compartments i.e., they contain water, and our cells obviously contain a genome and lots of DNA, RNA, proteins and sugars, but our aqueous compartments are very simple. They might just contain one protein or they might just contain a drug molecule and we're able to manipulate these using electronics or using light

Interviewer - Chris Smith

It sounds trivial when you first hear this, but of course I'm thinking that in order to achieve what you're doing, you're going to need a way of turning a layer of lipid, which is going to be the membrane, the oily bag that’s around our cells into a continuous envelope around that aqueous environment and that actually is more difficult.

Interviewee - Hagan Bayley

Yes. So, the really interesting trick that we have is that our compartments are just separated by a single lipid membrane.  So, most cells have a lipid membrane around them, so, if you bring two cells together they'll be separated by two lipids membranes and that makes it quite hard for them to communicate.  So, the human body is devised all sorts of ways to bridge the two membranes or to secrete chemicals that can be secreted by one cell and then recognized by another cell. But by having our compartments separated just by a single lipid bi-layer, we're able to put engineered membrane channels and pores into that bi-layer and get our aqueous compartments to communicate with each other and to communicate with the outside world and communication between cells is really the basis of how tissues work.

Interviewer - Chris Smith

So, you could physically insert into your membranes, ion channels - these little pores that cells have in their surfaces in order to allow ions to go backwards and forwards across the membrane and change the electrical activity of the cell. You can do that.

Interviewee - Hagan Bayley

That's correct and that's very important because if you have a piece of tissue that's really more than a few microns it’s very hard to get one side of the tissue to communicate with the other side of the tissue because diffusion is very, very slow.  So, cells in the body or tissues in the body communicate with each other electrically and these electrical signals can, number one, they can move very quickly and second they're directional. By printing these aqueous droplets, some of which contain ion channels and some of which don't, we can generate pathways within our artificial tissue that will act really just like neurons so we can transmit a signal from one side of the tissue to the other in a directional way, extremely quickly.

Interviewer - Chris Smith

To my untrained ear, it sounds like it would actually be fairly delicate, you end up with these droplets with little more than an oily bag around them, so how do you incorporate some degree of resilience and strength into this?

Interviewee - Hagan Bayley

Well, interestingly if you just build these in one dimension, they're really not that stable, but once you've printed them in three dimensions you can imagine a droplet in the middle being pulled on equally in all directions by its neighbors. So, they will just sit around for weeks in the dish and not collapse and they have the consistency of the sort of a fatty or maybe brain-like soft material. They're really are surprisingly robust.

Interviewer - Chris Smith

Could you therefore say, right, I have a basic understanding from physiology of what a kidney looks like and how it works.  I'm going to print a rudimentary kidney and I'm going to endow different droplets with different combinations of proteins to make them have certain functions, and I will build sort of a surrogate kidney in this way.

Interviewee - Hagan Bayley

Yes. In the long term that's what we'd like to do, maybe in the short term we'd like to do something simpler like make a material that might secrete a drug on demand that we think would be relatively simple to do.  But certainly our long term goal is to look at tissues and tissues are made up of different types of cells that are organized in different layers and to be able to mimic that by printing different types of droplets in a predetermined three dimensional design that might mimic various tissues. Some things like brain tissue or heart tissue would be very hard to do, but there might be other tissues like liver or pancreas that might be earlier targets for this kind of technology.

(13:32 - Historical parchment scrolls that have become too fragile to be unrolled could soon be read again thanks to an X-ray imaging technique - Digitally unrolling historical scrolls)

Interviewer - Chris Smith

Hagan Bayley from the University of Oxford. And now a way to make the previously unreadable, readable. Phil.

Interviewee  – Phil Robinson

So, this is developing a technique used in dentistry but applying it to reading old historical scrolls. So, as you're probably aware, scrolls from hundreds of years ago, they were written on parchment, these are derived from animal skins. Now they're often rolled up and over time, the substances that these are made of, particularly the collagen, will break down into gelatin effectively gluing these things together and obviously the parchment will dry out as well, so it can become very delicate and fragile and essentially you don't want to handle them. They'll also fall apart if you try to unroll them. There are a lot of these scrolls, in this condition that are now unreadable effectively. So Tim Wess at Cardiff University studies scrolls like this and he just happened to meet a chap called Graham Davis at Queen Mary University, he does work on dentistry and he uses a technique called x-ray tomography to look at teeth and so on. So, as you're probably aware, that involves taking two dimensional slices of a three dimensional object and then you reconstruct the three dimensional image from those slices.

Interviewer - Chris Smith

So one man says to the other could I do it for a scroll, what you do for teeth?

Interviewee – Phil Robinson

Precisely. He saw Graham talking about this technique and felt well that looks like it might work from these scrolls that I can't read but if you can get these slices and reconstruct that image, maybe we can read the text, we can virtually unroll that scroll once we have it stored in a computer and we can read the text.

Interviewer - Chris Smith

Does it work?

Interviewee – Phil Robinson

It does! They were rather surprised with it as well. They took some scrolls, in the first place, they just took some ordinary scrolls and rolled them up to see if it would work and then they went on to actually look at one of these unrollable scrolls that they have and they retrieved the text from it.

Interviewer - Chris Smith

What are the x-rays seeing, when it’s beaming inside the scroll and you're reading the text, what's it reading?

Interviewee – Phil Robinson

The reason this works quite well is because the x-rays pick up the difference between the pigments, that's an iron-gold pigment, that's on the parchment.

Interviewer - Chris Smith

The ink they're written with.

Interviewee – Phil Robinson

Exactly, the black ink. The iron there absorbs x-rays quite heavily, more so than the parchment, and so you get a contrast between the ink and the parchment and that allows you to pick out the text.

Interviewer - Chris Smith

Have they revealed any gory details or anything particularly exciting or anything spectacular yet?

Interviewee – Phil Robinson

Nothing interesting enough for them to include in the press release anyway.

Interviewer - Chris Smith

Nothing for Tatler yet though.

Interviewee – Phil Robinson
Exactly, exactly. But as we say there are thousands more out there that now potentially can be read using this technique.

(16:16 - Scientists in Canada have made a super-strong cell membrane adhesive and used it to stick red blood cells together - Super Glue for cells)

Interviewer - Chris Smith
Thanks Phil. And Neil, superglue for cells plus more.

Interviewee – Neil Withers

Some Canadian scientists have used what they know about cell membranes to make a sort of a polymer that's a superglue that can stick red blood cells altogether.

Interviewer - Chris Smith

How does it work?

Interviewee – Neil Withers

They were studying membranes and they found in pretty much in all cell membranes, there's phosphatidyl choline which has on the end of it a positive charge and they thought, well if you've got a positive charge, can we switch that around, get something with a negative charge on the end, that would then want to be next to the positive charge? So they used a pretty bog-standard biocompatible polymer, or rather the monomer that makes up that polymer, then they added a choline phosphate so the other way around and made the polymer that has these choline phosphate units all the way along and this polymer acts like a superglue.

Interviewer - Chris Smith

So, you decorate some cells with it and then another cell comes along and sticks on.

Interviewee – Neil Withers

And bash! They stick to it. So it’s like double sided sticky tape I guess, you could think of it as.

Interviewer - Chris Smith

Does it damage the cells or are they okay?

Interviewee – Neil Withers

I don't think so. They say that there was no damage to the cell membrane, so I think that means that the polymer could be used as a tissue sealant so you could use it glue up wounds perhaps on very very small wounds.

Interviewer - Chris Smith

Is it safe, is it biocompatible to put it into the body?

Interviewee – Neil Withers

The polymer they’ve used is a well known biocompatible one; I guess they've chosen that because they know it doesn't have any safety issues.

(17:51 - Chad Mirkin, Chemistry World Entrepreneur of the Year 2013, explains how programmable atom equivalents, made from DNA nanoparticles, can herald a range of new technologies including rapid medical diagnostic tools  - No small success)

Interviewer - Chris Smith

Neil Withers and talking of glue, stick with us because still to come here on the Chemistry World podcast which is sponsored by Waters, soya beans and clean hydrogen. First a DNA nanoparticle with a difference. Chad Mirkin…

Interviewee – Chad Mirkin

It’s kind of funny, we weren't thinking about developing anything that would be biologically important. In fact we were thinking about nanoparticles as atoms and asking should we take DNA and immobilize it on the surface of the particles and begin to create what we like to refer to as a programmable atom equivalent, a structure that will be like the nanoscale ball of velcro that could recognize other particles based upon the DNA on their surfaces and begin to bond with them in a very programmable and controllable way. The big dream was to learn how to take these particles and build from the bottom up new types of materials, materials that would have properties that derive from the type of particles you used and the type of DNA bonds that you used to join them together, and the periodicity of the particles throughout a three dimensional lattice.  It turned out along the way though we discovered that when you do this you create a new form of DNA, that is a form that has completely different properties from its linear cousin.  For example the ability to enter cells, we found the particles when you expose them to almost any cell type they'll naturally enter those cells, whereas linear nucleic acids won't.  And what that means is you can now get large amounts of genetic material inside cells and so this has led to a whole new class of diagnostic tools to begin to screen people for different types of diseases that have a genetic basis.

Interviewer - Chris Smith

So when you make these DNA nanoparticles, is the DNA wound up around whatever the core chemicals you put in there to do that or do you choose the sequence of the DNA so that it adopts that structure by binding to itself?

Interviewee – Chad Mirkin

What happens is we use the core, the nanoparticle core as a template. Then we synthesize DNA strands that have little sticky groups that can bond to the template, to the nanoparticle and then we created conditions, and that was an important part of the research that allowed us to really pack the number of DNA strands on the surface of the particle to the point that they were all standing upright. Now you have a particle that has this spherical arrangement of nucleic acids where all the DNA strands are standing upright and densely packed and that high-density structure that leads to all these fantastic properties.

Interviewer - Chris Smith

Well, how big is one of these particles?

Interviewee – Chad Mirkin

Well, the core is typically 13 nanometers in diameter and then when you put the DNA on the total particle ends up being between 35 and 50 nanometers in diameter.

Interviewer - Chris Smith

So that's on par with a small virus - norovirus, the winter vomiting bug, is about the same size as that particle, isn't it? How long are the individual pieces of DNA you've got on here then?

Interviewee – Chad Mirkin

They can be anywhere from 10 to 30 nanometers long.

Interviewer - Chris Smith

And in terms of DNA letters, how many genetic letters long is that?

Interviewee – Chad Mirkin

We can go from as few as 8 to as many as 80.

Interviewer - Chris Smith

But that's not very much, is it? I mean what can you do with a relatively short sequence of DNA like that?

Interviewee – Chad Mirkin

Oh! No, no, it’s extremely powerful. So we can create probes that will recognize targets and provide signals that tell us that target is present. So for example, a company we founded called Nanosphere has created a variety of chip based assays where you have many spots of DNA on the chip that can sample a solution for different types of DNA targets, targets associated with a given disease. The target goes to the right spot on the chip and then we sandwich with a nanoparticle probe, one of these spherical nucleic acids with gold nanoparticle conjugates, the core in that case is gold and it binds to the target and provides a signal and so we can see a color associated with that process but you can also take advantage of the catalytic properties of that particle. It turns out that if you flow photographic developing solution over this chip, anywhere you have particles, you plate out silver. The reason that's important is you can amplify the signal by a factor of a hundred thousand times in less than five minutes. So, what you end up getting is an incredibly sensitive diagnostic tool and so any bacterial infection, viral infection, any genetic disease can be screened with that type of technology.  And so an example of the technology that's particularly important is sepsis, a blood stream infection. If you get sepsis you have a major problem and in fact the longer you have sepsis without it being diagnosed, the greater chance of a death and it’s really critical that you can detect it, detect it quickly and identify the organisms with which the patient is infected and the reason that's important is you ultimately have to go on antibiotics and it’s important to know what organisms you're infected with to select the right types of antibiotics. Current tests take about three days. This test takes less than two hours. It’s a game changer in the whole medical field.

Interviewer - Chris Smith

What is the target that it’s seeing in septic patients?

Interviewee – Chad Mirkin

It’s looking at genetic fragments associated with the bacteria that the patient is infected with.

Interviewer - Chris Smith

So, if it’s as sensitive as you say, why did you get loads of false positives because one of the things about DNA is yes it does bind very selectively to its mirror image genetic sequence, but it also will bind to things that look a bit like its mirror image, but not quite.

Interviewee – Chad Mirkin

That's a wonderful question because it turns out another property of spherical nucleic acids is that when they bind to complementary DNA, they bind in what’s called a highly cooperative way and so when you heat and melt them, with spherical nucleic acids, you get melting transitions where the two DNA strands associate over a very, very narrow temperature range, as small as a single degree. Normal DNA, normal linear DNA will melt over temperature range of 25 to 30 degrees with these short strands. So, when you can get these highly cooperative melting transitions, you can actually pick a temperature that avoids the problem you just identified, where all the non-complementary strands melt, but the perfectly complementary one keeps the particle bound to the surface and provides the signal that you're looking for. So not only do you get exquisite sensitivity, the ability to fish out really low concentrations of these targets, but you get almost perfect selectivity.

Interviewer - Chris Smith

Sounds perfect.

Interviewee – Chad Mirkin

It’s unbelievable so it's I think it’s really spectacular.

Interviewer - Chris Smith

What happens if I put these things into the body though because that's very well that's on a chip can we also exploit the power of these things to say carry that genetic message into target cells?

Interviewee – Chad Mirkin

You absolutely can. So one of the really neat discoveries involving spherical nucleic acids was around 2006, where we did what was called a Friday afternoon experiment. Nobody thought that these types of structures could enter cells and the reason is that these are some of the mostly negatively charged entities, a big ball of negatively charged DNA. It turns out they not only go into cells, they go into cells better than anything known to man.  And the reason they can go into cells is they engage in what are called scavenger receptors on the surfaces of cells, and that triggers a process called endocytosis, which sucks the particles up and takes them into the cells.  And now you can get very large amounts of nucleic acids in the cells and you can begin to flip genetic switches associated with the disease. We're now using this to create a large class of therapeutic compounds for many different diseases, cancer, neurodegenerative diseases. We even found that it could go through the skin. You can put them in ordinary creams and that means, you now for the first time can think about using gene regulation technology to treat diseases of the skin, things like melanoma, psoriasis, facilitate wound healing. You can even think about creating new types of cosmetics based upon these structures.

(26:14 - A catalyst made from soybeans could overcome a major barrier to cheap hydrogen fuel - Soybean catalyst for hydrogen evolution)

Interviewer - Chris Smith

Chad Mirkin from Northwestern University. And now beans means not Heinz, but hydrogen. Emma…

Interviewee – Emma Stoye

So this is a group who have found that you can use soy beans as a catalyst to help get hydrogen from water.

Interviewer - Chris Smith

How on earth did they make that breakthrough? I nearly said break wind! You know what they say about beans, but how did they discover this?

Interviewee – Emma Stoye

They've been working on trying to get different catalysts to make hydrogen in this way because the thing that most people use at the moment is platinum, which is not particularly cheap. They've been working a lot with molybdenum which is just a transition metal, it’s way cheaper than platinum, and they found that molybdenum carbide acts as quite a good catalyst. The problem is it’s not very stable in acidic conditions, so it’s no use really for that reaction. So they were working on this and they actually had a couple of students in their lab, this is at Brookhaven National Laboratory in New York, James Muckerman and Wei-Fu Chen. They had these students and they set them a bit of a mission and they said, we want you to find something which is cheap and abundant and you can combine it with molybdenum. These students went off, they brought back all sorts of stuff, leaves and flowers and vegetables and…

Interviewer - Chris Smith

Chemistry foraging!

Interviewee – Emma Stoye

Yeah exactly. A lot of it didn't work, but weirdly soy beans did work quite well! You grind up these soy beans, and combine them with molybdenum and the carbon and the nitrogen makes molybdenum carbide, but also molybdenum nitride. This works well as a catalyst because molybdenum carbide is a good catalyst, but doesn't work under acidic conditions.  Molybdenum nitride is the exact opposite, it’s very stable and corrosion resistant but it’s not such a good catalyst. But the two together, which is what you get when you mix these soy beans and make this composite material which works well as a catalyst and is stable in acidic conditions.

Interviewer - Chris Smith

So how would we use it?

Interviewee – Emma Stoye

It’s an electrolysis reaction, so you would make this catalyst sort of on the electrodes that you're using with an electrical current through.

Interviewer - Chris Smith

And split the water.

Interviewee – Emma Stoye

Yes split the water and get hydrogen.

(28:32 - Researchers in China have discovered a new method of male contraception: a quick injection of gold nanorods into the testes, followed by a 10 minute dose of infrared light - Will nanorods be the next big male contraceptive idea?)

Interviewer - Chris Smith

Now everyone thought, thank you Emma, that James Bond was the man with the golden gun but may be that your local vet could be the man with the golden gun, Phil.

Interviewee – Phil Robinson

That could be in the future Chris. So what we have is a new technique for a male contraception. Now this story begins with the goal of sterilizing pets. You have cats don't you Chris?

Interviewer - Chris Smith

Yeah, not willingly.

Interviewee – Phil Robinson

I see well then perhaps you haven't taken the precaution of safeguarding their reproductive abilities.

Interviewer - Chris Smith

I have actually, but I just didn't buy the blinking things, they're my wife's acquisition.

Interviewee – Phil Robinson

Right, right, but you are a responsible pet owner.

Interviewer - Chris Smith

I have taken my responsibility seriously.

Interviewee – Phil Robinson

Well I'm pleased to hear it.

Interviewer - Chris Smith

Much to the chagrin of next door's cat, I have to say, because he's been around every day.

Interviewee – Phil Robinson

He's been around sniffing. Right I see. We should take him to the vet as well, give him in a little treat. Anyway

Interviewer - Chris Smith

So, how does this work?

Interviewee – Phil Robinson

As you know, the current process of neutering your animals is fairly invasive and quite expensive as well, so alternatives to this that are simpler and cheaper are obviously desirable. So, some scientists in China, Fei Sun and his team and the University of Science of Technology of China have come up with a different mode of contraception or sterilization which is to use gold nanorods.

Interviewer - Chris Smith

Where?

Interviewee – Phil Robinson

Thereby hangs the tale, Chris, where indeed? They're injected just a small injection, simple injection.

Interviewer - Chris Smith

That’s what they always say.

Interviewee – Phil Robinson

Just a little prick Chris.

Interviewer - Chris Smith

That’s what they always say!

Interviewee – Phil Robinson

Directly into your testicles.

Interviewer - Chris Smith

Not to me of course,

Interviewee – Phil Robinson

No no of course not.

Interviewer - Chris Smith

So you put the gold nanorods into the testes.

Interviewee – Phil Robinson

Into the testicles yeah, and then you fire a laser at the testicles. It gets better.

Interviewer - Chris Smith

What sort of wavelength of laser?

Interviewee – Phil Robinson

So these are near infrared lasers and the gold nanorods respond to that laser by heating up and as you know, if you subject the testicle - testicles are very sensitive to heat, temperature of course.

Interviewer - Chris Smith

I'll say!

Interviewee – Phil Robinson

Very sensitive in general! But yeah if you heat them up that will cause the reproductive tenacity of the testicles to diminish.

Interviewer - Chris Smith

People who spend lot of time with their legs together. Lorry drivers, taxi drivers, bus drivers, and laptop users as it turns out and high lap temperatures have lower sperm counts, as opposed to its taking advantage of the fact that optimum sperm production occurs at a couple of degrees below body temperature.

Interviewee – Phil Robinson

Exactly exactly, the very reason why they helpfully hang around just outside of the body.

Interviewer - Chris Smith

So how warm do you have to make them to get the effects?

Interviewee – Phil Robinson

So the models they've used in this case were mice, they injected mice with these nanorods and they found out that if they heated the mouse testicles using these nanorods to 45 degrees, that resulted in complete sterilization but at 40 degrees the effects were only temporary and the mice were reproductively active again a week later.

Interviewer - Chris Smith

Can't you just use a saucepan of warm water.

Interviewee – Phil Robinson

I suppose you could, although the advantage here is that you ensure consisting heating throughout you don't have to sit with your testicles in a pan of water.

Interviewer - Chris Smith

Well then that could be fun. Would you volunteer?

Interviewee – Phil Robinson

I don't think I'll be first in the queue Chris I have to say.

Interviewer - Chris Smith

I don't think I'd even be in the queue.

Interviewee – Phil Robinson

If that time ever came along, I think I'll still prefer the invasive snip to be honest, over the testicular injection.

Interviewer - Chris Smith

And the laser?

Interviewee – Phil Robinson

Followed by laser treatment

(32:02 - Trivia - Who had a busy day with the periodic table 205 years ago?)

Interviewer - Chris Smith

Yeah, if they tune it wrong, it could have dire consequences. So what about the trivia this month, what have you got for us?

Interviewee – Phil Robinson

Okay this week, so we’re asking the question: who had a busy day with the periodic table 205 years ago?

Interviewer - Chris Smith

Who was around 205 years ago I'm thinking people like Henry Cavendish?

Interviewee – Phil Robinson

Almost, well not almost, it is a different person.

Interviewer - Chris Smith

Priestly?

Interviewee – Phil Robinson

Priestly is bit older.

Interviewer - Chris Smith

Black?

Interviewee – Phil Robinson

Older again.

Interviewer - Chris Smith

Okay, Humphrey Davey?

Interviewee – Phil Robinson

Humphrey Davey, yes, indeed, indeed got there in the end. So Humphrey Davey, well known for discovering many many elements but on this particular day.

Interviewer - Chris Smith

Sniffing them too. He used to smell everything.

Interviewee – Phil Robinson

Yeah yeah well. A lot his work was done through electrolysis, and yeah, that will be releasing gases and smelling them to find out what they were.

Interviewer - Chris Smith

Soya beans.

Interviewee – Phil Robinson

Not something that would recommend that you do today, of course.

Interviewer - Chris Smith

So, what did he discover this day 200 plus years ago.

Interviewee – Phil Robinson

So, 205 years ago, he essentially discovered group II, so magnesium, calcium, strontium and barium.

Interviewer - Chris Smith

Any reason why all those things in Group II came out together, was there something about the techniques that he was using that meant all of them just dropped out at the same time or had he consistently been trying to find everything in group II and that's why he then published the sequence there.

Interviewee – Phil Robinson

I can't give a definitive answer there. I suspect, he was certainly using a single technique of electrolysis. So that's a very easy technique. These particular elements will all form quite simple salts with non-metals and so it would be easy to separate these by electrolysis. He tried to get a lot of other things by electrolysis as well, but he wasn't always successful and it fell to other investigators and their development of other techniques to get those tricky around this.

Interviewer - Chris Smith

Thanks to Phil Robinson and the rest of the Chemistry World team this month, Neil Withers and Emma Stoye. The Chemistry World podcast is sponsored by Waters, who are world leaders in innovative analytical science solutions and I'm Chris Smith from thenakedscientists.com. And I'll be back next month with more cutting-edge chemistry, until then though Goodbye!

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