Looking to Nature For Material Inspiration

Abalone build hard shells; diatoms build tiny cages of glass. Can they teach humans to build better batteries, or solar cells? Angela Belcher, a materials scientist at MIT, describes her efforts to enlist the aid of viruses, yeasts, and other organisms to help build better materials for technology.

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JOE PALCA, host: If you look at the material chalk and a precious pearl, chemically they're pretty similar, but one is soft and the other is hard. One is cheap and the other gets made into jewelry. The difference is in the way the materials are structured, and in this - and in the case of the pearl, the way that the materials are assembled by a living organism building up the pearl layer by layer in just the right way. Or consider the way that tiny organism called diatoms can build complicated shells of glass and do it not with molten glass factory - in a factory clean room but in ocean water at regular temperatures.

What does nature know about building stuff that we don't? Well, quite a bit. And can we learn their secrets? Well, I think my next guest thinks maybe we can. She's Angela Belcher, the W.M. Keck Professor of Energy in the Department of Materials Science and Engineering and in the Department of Bioengineering at MIT, and her lab studies ways to use some of those natural tricks to build things humans want, like batteries or solar cells. She joins me from a studio on the MIT campus. Thanks for joining us today.

ANGELA BELCHER: Thank you for having me.

PALCA: So what got you started in this field?

BELCHER: Well, that was a great introduction. I did my Ph.D. on how abalones grow shells, and I was fascinated by the really exquisite structure of the abalone shell. As you mentioned, it's made out of chalk, and we're all familiar with chalk, and many of us are probably familiar with abalone shells. Well, if you take that shell structure and you look at it under high magnification, you basically fracture it, and you look at it, what you find is it's made up of plates of calcium carbonate, plates of chalk that are structured in a way that's quite a bit different than the way that chalk looks.

And if you look even closer, you find out, well, it's not all inorganic material. It's - there's a biological component to it that the organism, the abalone, makes this mostly inorganic material but has about 2 percent by weight of protein. And this protein actually has a huge impact on this material. It has impact on the way this material looks, the beautiful lustrous structure of pearls or abalone shells, but it also has a big impact on the structure itself. It makes it a tough structure, and the mineral structure, the way the atoms are actually arranged in the structure of this material are quite a bit - can be quite a bit different than chalk. It can use one form or another. And, to me, that was really fascinating.

PALCA: We're talking with Angela Belcher about using natural organisms to make incredible things. You can join us at 800-989-TALK. That's 800-989-8255. I'm Joe Palca, and this is SCIENCE FRIDAY from NPR.

So what - I mean, OK, so you study these things, and you look - you described looking at them under the microscope. So now, you've got - the skill you need is a microscopy skill. You talked about putting down layers. You need a materials science skill. You need a chemical skill. How - what do you bring to the table if you want to study these organisms?

BELCHER: Well, you know, people have actually understood the structure of pearls and shells for quite a while, and it's this combination of biology plus materials and biology plus the inorganic component that make it so valuable. And it's - you can look at the shell and - like you said, you can look at it under the microscope but after the process has already taken place. What's really interesting is actually the dynamic process: how the organism makes the calcium carbon there, how it makes the material because the organism has cells.

And these cells are pumping out proteins, and these proteins actually can grab on to ions and solutions, so ions in the ocean, and put them together basically in layers of ions in groups of - groups of ions and atoms. So they build up a structure exactly the way that they need the structure to be, the way that it's actually the strongest and toughest structure so it can withstand things in the environment like otters and other kinds of things that would happen in this environment.

But the thing that's interesting is that it has a DNA sequence. The abalone has a DNA sequence that codes for the ability to string amino acids together in the right order so that it can efficiently and effectively grab what it needs from its environment and starting to build it up atom by atom by atom. And by doing so produces this structure that has a lot of interesting materials. So, to me as a material scientist and as a biological engineer, you think, you know, what a great system.

The organism took what's in its environment and built up a higher value structure. That structure is something very useful. And so you can look at it in an electron microscope under high magnification and look at the structure. But then, you can also say, well, you know, how did it make those proteins? How did it secrete those proteins, and why are they specific to be able to grow this particular kind of mineral? And then, you can look back even further and say, well, you know, they have this DNA sequence.

They have this sequence encoded in the genome that says this is how to build a great shell. This is how to build it. And so, for me, I look at that and I say, OK, if an organism can build a shell, what if we could get simpler organisms to build other things that are more useful to us. If we have a DNA sequence that codes for a protein sequence to start building materials that could be an electronic material or could be a material that is an interesting catalyst for other kinds of chemical reactions. Or what if you had a - you could build a solar cell.

PALCA: Angela Belcher, you're going to have to give us all the various things that you are now working on to make, but we're going to have to wait and do that after the break. We're talking with Angela Belcher. She's a professor of energy in the Department of Materials Science at MIT, and her lab studies ways to use some natural tricks to make some interesting things. We'll be right back.

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PALCA: This is SCIENCE FRIDAY from NPR.

This is SCIENCE FRIDAY. I'm Joe Palca. We're talking this hour about making materials inspired by nature. I'm talking with Angela Belcher. She's the W.M. Keck Professor of Energy in the Department of Materials Science and Engineering and in the Department of Bioengineering at MIT.

And, Angela Belcher, you were just about to enumerate some of - I mean, assuming that making a better abalone shell is only one of your goals, what else you might be able to get these organisms to do that would be of interest to us?

BELCHER: Well, that's a great point. So we look at abalone shells, and you say, well, abalone have done a fantastic job of making these kinds of structures that I'm personally not interested in building on those structures. And abalones had about 50 million years to get good at making abalone shells, and so they have a really good head start. What we started thinking about was, well, what if - so there's only a couple of elements in the ocean that organisms have started building hard materials out of.

And as mentioned before, calcium carbonate or calcium phosphate, like our bones. There's some iron structures, iron oxide. And as was mentioned earlier, diatoms made out of silica. What we decided to do was what if organisms could work with a much larger part of the periodic table? What if we could give them most of the periodic table to work with? And if we could find a DNA sequence that coded for a protein sequence that could grab onto those atoms or those elements and start building them up into useful structures, what would we want to make, and how could biology facilitate that?

And so that's what we've been doing pretty much the last five or six years, is trying to make useful devices and useful materials that can have an impact on society. And we've looked at materials for batteries, for energy storage. Can you find a biological sequence that can assemble batteries to make good batteries that are made from environmentally-friendly materials that can be made with solution-based processing and assemble themselves? We've...

PALCA: No, go ahead.

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BELCHER: We've been doing the same thing with solar cells. And we had a paper out this year on trying to increase and being able to increase the efficiency of a particular kind of solar cell by using a virus - that's a simple virus, that's a bacterial virus that has no effect on humans - giving it the ability to grab onto carbon nanotubes and at the same time to be able to build titania, to build - to incorporate into already existing solar cells. So those are two examples that we've been working on.

PALCA: Well, let's take a call now and go to Benjamin. Benjamin, you're on the air. Benjamin from Girard, Illinois, welcome to SCIENCE FRIDAY. You're on the air.

BENJAMIN: Thank you very much. Thank you for having such a fascinating topic today. I wanted to ask Angela if - in her work, if she's seen an overlap in the legacy and work that Buckminster Fuller had done in his creation of, like, the geodesic dome, and if she also saw any overlap in her field into like sacred geometry or the golden mean or the number phi, which seems to be recurrent in all these natural structures.

PALCA: OK, Girard(ph), thanks for that. What about that idea?

BELCHER: Well, in terms of the interesting architecture, that's one of the things that we've focused on. And we've used materials, carbon-based materials like Buckyballs or carbon nanotubes which have - we didn't look at them as much for the geometry but because of their really fantastic electronic properties. We've been working with getting organisms to pick them up and organize them into units that are actually useful for us. And that's one of the things that we've done with our solar cells.

So, you know, if you look at patterns in biology, I think you'll see a lot of really interesting geometric patterns which go to make materials that are functional. And so I agree with that 100 percent.

I don't know - I don't really know much about the numbers that you were talking about exactly, but I do know that we really care about numbers of atoms in structures. We're interested in materials that conform with only a small cluster of atoms in a really defined location and defined space to form materials that could subsume in the larger structures.

So this is interesting to us because we work on nanostructure materials and small nanostructure materials. And by controlling which atoms are on the surface or in which layers, it really changes the properties of a material. It can make a material a better catalyst. It could make a material - one particular kind of semiconductor versus another to have very useful properties. So I definitely see a correlation and an overlap in that. We think of it from the collection and putting atoms together in a very specific way to try to get a particular kind of function we want out.

PALCA: But I'm curious now, do you - when you're getting these organisms to do their interesting things, are you changing what they have to feed on? Or are you trying to change them as well?

BELCHER: We're actually trying to change them. So we mostly use a virus. It's a bacteria virus called M13 bacteriophage, which is a virus that...

PALCA: A very catchy name.

BELCHER: It's a virus that infects just bacteria. And it's - have single-stranded DNA, and it's surrounded by proteins that its DNA codes for. And what we do is we go into its DNA sequence and we use, basically, enzymes, molecular enzymes, and we cut up the DNA and we replace it with a random DNA sequence. And using modern molecular biology, a technique - this is pretty straightforward to do. And you can basically create a library. If you do that a billion times, you go in and take a DNA sequence and put in a small random DNA sequence in - but do that a billion different times, what you can do is get these viruses all genetically identical, but they differ from each other based on a small DNA sequence, which corresponds to a small peptide or a small protein sequence.

And now, what you can do is you can have a billion different of these bacterial viruses and just a couple of drops of solution in the lab. And you take those billion possibilities, and we don't know which one is going to be the best for a solar cell. We don't know which one of those can be best for a battery. And we say, OK, let's take all billion at once and let's take a little pipette and let's drop it onto some battery material and try to force it to interact with that material. The idea goes back to just like an abalone grabs calcium and carbonate as a solution and organizes them into a nice material. Let's have the virus grab - if you're doing, say, it's iron phosphate, say, making a battery - grab the iron and phosphate and start using it and structuring it in a way that would be advantageous for us.

And so let's take a billion possibilities. And maybe only 100 out of a billion will have any affinity for our battery, electrical material. So let's get rid of the rest. Let's take that 100 and let's say, OK, now, let's make it harder for it to interact. Let's get down to 10, and eventually, let's get down to one. So let's get down to one sequence out of a billion that can grow a battery electrode or that can grow material for a solar cell. Why don't we do a billion years - why do a billion experiments at a time? Because we don't have millions of years of evolution to look for the sequence at work. So let's try a billion experiments a time and start narrowing it down.

PALCA: It sounded a bit like evolution there, but it sounds like using it in a slightly different way. But let's take a call now and go to Carl in Oshkosh, Wisconsin. Carl, you're on the air with SCIENCE FRIDAY.

CARL: Yeah. Greetings. First off, I love SCIENCE FRIDAY. Second of all, I was curious with the idea of trying to manipulate the cells and bacteria or the vector - the organisms to try to latch onto other larger molecules, heavier metals and such like that. Is there a possibility of thought of trying to do that, maybe lock onto, like, nuclear waste, for instance, like in Nakashino(ph) power plant or various other things?

BELCHER: Yeah.

CARL: And I'm going to take my answer off the air.

PALCA: OK. Thanks, Carl. Go ahead, Angela.

BELCHER: Thanks for that question. And, you know, that's a - people have been thinking about that more in the last couple of years, is can you use natural biological molecules to do things like latch on to molecules that you want to be able to sequester and be able to store and get rid of, like that example. And that's something we've been really interested in. we've looked at it for trying to remove waste from water, for example, to try to pull it out into - to chelate it. And that's actually an area that we're getting more interested going into again because we've started developing new platforms where we think it could be - we could work on a larger scale of trying to remove materials or toxins from the environment. That's a great question, thank you.

PALCA: I've read that you've also done some work about trying to take carbon dioxide out of the atmosphere.

BELCHER: That's right. We do have a program on carbon capture and storage. And the idea came about again from how abalones can store carbon and calcium carbonate. And we have a project where we've been working on engineering organisms, including yeast, to try to pull CO2 out of a mock, waste from a power plant, and convert it into useful materials that you could use as building materials.

PALCA: So is this approach something that other scientists have jumped on board with? And are you a bit of an iconoclast in this area?

BELCHER: Well, I think that people have been interested in using biology to make materials for a while. And I think that the - I - the way that we do it has been repeated by other groups around the world successfully. And people have come up with their own different innovative ideas of doing it, maybe not just with bacteriophage, but maybe other kinds of viruses or with protein components by themselves or DNA. But they all take into account the idea that biology gives you beautiful structure. It gives you really nice chemical functionality and chemical handles that you can use to grab on to things and bring them together. It uses the idea of solution-based processing and self-assembly and clean manufacturing. So I'm pretty proud of what my group has done in terms of, you know, developing the technology and then using it to actually make real devices that you can hold in your hand. But there's been a great increase in interest in it in the last couple of years.

PALCA: Care to predict when the first one will come on the market?

BELCHER: When the first...

PALCA: The first marketable device.

BELCHER: Yeah. So I was fortunate to be a founder of a company called Siluria Technologies that's in San Francisco. And they've taken the - some of the biological technologies that we developed in the lab, some of the platform. And, you know, taken it into a startup company, which has just done a really fantastic job of combining the biological technologies that we developed with chemical combinatorial chemistry. So adding, basically, a way of adding lots of different elements and lots of different chemistries into the system. So it's kind of taking the power of biology and the power of combinatorial chemistry and then combining that with rapid throughput screening to look for new materials, catalytic materials that can be used in the chemical industry and in the fuel industry.

And, you know, I hate to put a prediction on the time to commercialization, but I can tell you that they're going very rapidly. And it's the, you know, taking the different powerful techniques and combining it together in a very unique way that enable them to develop new catalysts for some pretty important chemical reactions, one of which is called the oxidative coupling of methane, which is taking a methane, which is just a carbon with single carbon and adding more carbons to it in a way that is much higher valued, to build materials up from methane into materials that could be specialty chemicals and plastics and even fuel.

PALCA: All right. Well, we'll be watching for that. Thanks very much, Angela Belcher. She's the W.M. Keck professor of energy in the Department of Material Science and Engineering and the Department of Bioengineering at MIT. This is SCIENCE FRIDAY and I'm Joe Palca.

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