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  • I thought I would talk a little bit about how nature makes materials.

  • I brought along with me an abalone shell.

  • This abalone shell is a biocomposite material

  • that's 98 percent by mass calcium carbonate

  • and two percent by mass protein.

  • Yet, it's 3,000 times tougher

  • than its geological counterpart.

  • And a lot of people might use structures like abalone shells,

  • like chalk.

  • I've been fascinated by how nature makes materials,

  • and there's a lot of sequence

  • to how they do such an exquisite job.

  • Part of it is that these materials

  • are macroscopic in structure,

  • but they're formed at the nanoscale.

  • They're formed at the nanoscale,

  • and they use proteins that are coded by the genetic level

  • that allow them to build these really exquisite structures.

  • So something I think is very fascinating

  • is what if you could give life

  • to non-living structures,

  • like batteries and like solar cells?

  • What if they had some of the same capabilities

  • that an abalone shell did,

  • in terms of being able

  • to build really exquisite structures

  • at room temperature and room pressure,

  • using non-toxic chemicals

  • and adding no toxic materials back into the environment?

  • So that's the vision that I've been thinking about.

  • And so what if you could grow a battery in a petri dish?

  • Or, what if you could give genetic information to a battery

  • so that it could actually become better

  • as a function of time,

  • and do so in an environmentally friendly way?

  • And so, going back to this abalone shell,

  • besides being nano-structured,

  • one thing that's fascinating,

  • is when a male and a female abalone get together,

  • they pass on the genetic information

  • that says, "This is how to build an exquisite material.

  • Here's how to do it at room temperature and pressure,

  • using non-toxic materials."

  • Same with diatoms, which are shone right here, which are glasseous structures.

  • Every time the diatoms replicate,

  • they give the genetic information that says,

  • "Here's how to build glass in the ocean

  • that's perfectly nano-structured.

  • And you can do it the same, over and over again."

  • So what if you could do the same thing

  • with a solar cell or a battery?

  • I like to say my favorite biomaterial is my four year-old.

  • But anyone who's ever had, or knows, small children

  • knows they're incredibly complex organisms.

  • And so if you wanted to convince them

  • to do something they don't want to do, it's very difficult.

  • So when we think about future technologies,

  • we actually think of using bacteria and virus,

  • simple organisms.

  • Can you convince them to work with a new tool box,

  • so that they can build a structure

  • that will be important to me?

  • Also, we think about future technologies.

  • We start with the beginning of Earth.

  • Basically, it took a billion years

  • to have life on Earth.

  • And very rapidly, they became multi-cellular,

  • they could replicate, they could use photosynthesis

  • as a way of getting their energy source.

  • But it wasn't until about 500 million years ago --

  • during the Cambrian geologic time period --

  • that organisms in the ocean started making hard materials.

  • Before that they were all soft, fluffy structures.

  • And it was during this time

  • that there was increased calcium and iron

  • and silicon in the environment.

  • And organisms learned how to make hard materials.

  • And so that's what I would like be able to do --

  • convince biology

  • to work with the rest of the periodic table.

  • Now if you look at biology,

  • there's many structures like DNA and antibodies

  • and proteins and ribosomes that you've heard about

  • that are already nano-structured.

  • So nature already gives us

  • really exquisite structures on the nanoscale.

  • What if we could harness them

  • and convince them to not be an antibody

  • that does something like HIV?

  • But what if we could convince them

  • to build a solar cell for us?

  • So here are some examples: these are some natural shells.

  • There are natural biological materials.

  • The abalone shell here -- and if you fracture it,

  • you can look at the fact that it's nano-structured.

  • There's diatoms made out of SIO2,

  • and they're magnetotactic bacteria

  • that make small, single-domain magnets used for navigation.

  • What all these have in common

  • is these materials are structured at the nanoscale,

  • and they have a DNA sequence

  • that codes for a protein sequence,

  • that gives them the blueprint

  • to be able to build these really wonderful structures.

  • Now, going back to the abalone shell,

  • the abalone makes this shell by having these proteins.

  • These proteins are very negatively charged.

  • And they can pull calcium out of the environment,

  • put down a layer of calcium and then carbonate, calcium and carbonate.

  • It has the chemical sequences of amino acids

  • which says, "This is how to build the structure.

  • Here's the DNA sequence, here's the protein sequence

  • in order to do it."

  • And so an interesting idea is, what if you could take any material that you wanted,

  • or any element on the periodic table,

  • and find its corresponding DNA sequence,

  • then code it for a corresponding protein sequence

  • to build a structure, but not build an abalone shell --

  • build something that, through nature,

  • it has never had the opportunity to work with yet.

  • And so here's the periodic table.

  • And I absolutely love the periodic table.

  • Every year for the incoming freshman class at MIT,

  • I have a periodic table made that says,

  • "Welcome to MIT. Now you're in your element."

  • And you flip it over, and it's the amino acids

  • with the PH at which they have different charges.

  • And so I give this out to thousands of people.

  • And I know it says MIT, and this is Caltech,

  • but I have a couple extra if people want it.

  • And I was really fortunate

  • to have President Obama visit my lab this year

  • on his visit to MIT,

  • and I really wanted to give him a periodic table.

  • So I stayed up at night, and I talked to my husband,

  • "How do I give President Obama a periodic table?

  • What if he says, 'Oh, I already have one,'

  • or, 'I've already memorized it'?"

  • And so he came to visit my lab

  • and looked around -- it was a great visit.

  • And then afterward, I said,

  • "Sir, I want to give you the periodic table

  • in case you're ever in a bind and need to calculate molecular weight."

  • And I thought molecular weight sounded much less nerdy

  • than molar mass.

  • And so he looked at it,

  • and he said,

  • "Thank you. I'll look at it periodically."

  • (Laughter)

  • (Applause)

  • And later in a lecture that he gave on clean energy,

  • he pulled it out and said,

  • "And people at MIT, they give out periodic tables."

  • So basically what I didn't tell you

  • is that about 500 million years ago, organisms starter making materials,

  • but it took them about 50 million years to get good at it.

  • It took them about 50 million years

  • to learn how to perfect how to make that abalone shell.

  • And that's a hard sell to a graduate student.

  • "I have this great project -- 50 million years."

  • And so we had to develop a way

  • of trying to do this more rapidly.

  • And so we use a virus that's a non-toxic virus

  • called M13 bacteriophage

  • that's job is to infect bacteria.

  • Well it has a simple DNA structure

  • that you can go in and cut and paste

  • additional DNA sequences into it.

  • And by doing that, it allows the virus

  • to express random protein sequences.

  • And this is pretty easy biotechnology.

  • And you could basically do this a billion times.

  • And so you can go in and have a billion different viruses

  • that are all genetically identical,

  • but they differ from each other based on their tips,

  • on one sequence

  • that codes for one protein.

  • Now if you take all billion viruses,

  • and you can put them in one drop of liquid,

  • you can force them to interact with anything you want on the periodic table.

  • And through a process of selection evolution,

  • you can pull one of a billion that does something that you'd like it to do,

  • like grow a battery or grow a solar cell.

  • So basically, viruses can't replicate themselves, they need a host.

  • Once you find that one out of a billion,

  • you infect it into a bacteria,

  • and you make millions and billions of copies

  • of that particular sequence.

  • And so the other thing that's beautiful about biology

  • is that biology gives you really exquisite structures

  • with nice link scales.

  • And these viruses are long and skinny,

  • and we can get them to express the ability

  • to grow something like semiconductors

  • or materials for batteries.

  • Now this is a high-powered battery that we grew in my lab.

  • We engineered a virus to pick up carbon nanotubes.

  • So one part of the virus grabs a carbon nanotube.

  • The other part of the virus has a sequence

  • that can grow an electrode material for a battery.

  • And then it wires itself to the current collector.

  • And so through a process of selection evolution,

  • we went from having a virus that made a crummy battery

  • to a virus that made a good battery

  • to a virus that made a record-breaking, high-powered battery

  • that's all made at room temperature, basically at the bench top.

  • And that battery went to the White House for a press conference.

  • I brought it here.

  • You can see it in this case -- that's lighting this LED.

  • Now if we could scale this,

  • you could actually use it

  • to run your Prius,

  • which is my dream -- to be able to drive a virus-powered car.

  • But it's basically --

  • you can pull one out of a billion.

  • You can make lots of amplifications to it.

  • Basically, you make an amplification in the lab.

  • And then you get it to self-assemble

  • into a structure like a battery.

  • We're able to do this also with catalysis.

  • This is the example

  • of photocatalytic splitting of water.

  • And what we've been able to do

  • is engineer a virus to basically take dye absorbing molecules

  • and line them up on the surface of the virus

  • so it acts as an antenna,

  • and you get an energy transfer across the virus.

  • And then we give it a second gene

  • to grow an inorganic material

  • that can be used to split water

  • into oxygen and hydrogen,

  • that can be used for clean fuels.

  • And I brought an example with me of that today.

  • My students promised me it would work.

  • These are virus-assembled nanowires.

  • When you shine light on them, you can see them bubbling.

  • In this case, you're seeing oxygen bubbles come out.

  • And basically by controlling the genes,

  • you can control multiple materials to improve your device performance.

  • The last example are solar cells.

  • You can also do this with solar cells.

  • We've been able to engineer viruses

  • to pick up carbon nanotubes

  • and then grow titanium dioxide around them --

  • and use as a way of getting electrons through the device.

  • And what we've found is that, through genetic engineering,

  • we can actually increase

  • the efficiencies of these solar cells

  • to record numbers

  • for these types of dye-sensitized systems.

  • And I brought one of those as well

  • that you can play around with outside afterward.

  • So this is a virus-based solar cell.

  • Through evolution and selection,

  • we took it from an eight percent efficiency solar cell