Using nature to grow batteries Angela Belcher

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 bio composite

material that’s ninety eight percent by

mass calcium carbonate and two percent

by mass protein yet it’s three thousand

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

secrets to how they do such an exquisite

job part of it is that these materials

are or macroscopic and structure but

they’re formed at the nano scale the

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 kind

of the vision that that 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 environmentally friendly way

and so going back to this abalone shell

one thing besides being nanostructured

one thing that’s fascinating is when a

male and 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 is shown right here which are

glassy asst 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 nanostructured 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 biomaterials my four-year-old

ma’am but anyone who’s ever had or no

small children other incredibly complex

organisms and so if you wanted to

convince them to do something that they

don’t want to do it’s very difficult and

so when we think of

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 would be

important to me also we think about

future technologies we start with the

beginning of earth basically took a

billion years to have have life on earth

and very rapidly they became

multicellular they could replicate they

could use photosynthesis as a way of

getting their energy source but it was

until about 500 million years ago during

the Cambrian geologic time period that

organisms in the ocean started making

hard materials before that they’re 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 to be able to do convince

biology to work with the rest of the

periodic table now if you look at 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 not you know be an antibody that

that does something like HIV but what if

we could convince them to build a solar

cell for us and so here’s some examples

of some natural shells those natural

biological materials the abalone shell

here and if you fracture you can look at

the fact that it’s nanostructured

there’s diatoms made out of sio2 and

they’re magnetotactic bacteria that

makes 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 abilene makes the

shell by having these proteins these

proteins are very negatively charged and

you 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 the coded for a corresponding

protein

sequence to build a structure but not

build an abalone shell build something

that through nature’s had 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 may that

says welcome to MIT now you’re in your

element and you flip it over and it’s

the amino acids with with the pH at

which they have different charges and so

do i give us out to thousands of people

and i know it says MIT this is cal tech

but i have a couple extra if people want

it and I was really fortunate to have

president obama visit my lab this year

and 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 you know give President Obama

periodic table what if he says I already

have one I’ve already memorized it and

so he came to visit lab and then looked

around it was a great visit and then

afterwards 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 and so he looked at it

and he said thank you i’ll look at it

periodically and

later in a lecture that he gave on clean

energy p pulled it out and said look at

people at MIT they give out periodic

tables so so basically one what I didn’t

tell you is that it’s about 500 million

years ago that organism started making

materials but it took him about 50

million years to get good at it took

about 50 million years to learn how to

perfect how to make that abalone shell

that’s that’s a hard sell to a graduate

student I had this great project 50

million years and so we had to develop a

way of trying to do this more rapidly

and we use a virus that’s a non-toxic

virus called m13 bacteriophage this job

is to infect bacteria what has a simple

DNA structure we 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 can basically do this a billion

times and so you can go in and have a

billion different viruses are all

genetically identical but they differ

from each other based on their 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 out of a

billion that does something that you’d

like you to do like grow a battery or

grow a solar cell and so basically

viruses can’t replicate themselves they

need a host once you find that one out

of a billion you infect 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 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 viruses to pick up carbon

nanotubes so one part of the virus grabs

a carbon nanotube the other part of

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 being

able to have a virus who made kind of a

crummy battery to a virus it 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 and I brought it here

you can see it in this case

that’s lighting this LED now if we could

scale this you could you actually use it

to to drive your run your Prius which is

kind of my dream to be able to drive a

virus powered car but it’s basically

where you would basically even 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 die

absorbing molecules and line them up on

the surface of the virus acts as an

antenna and you get a 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 could be

used for for clean fuels and I brought

an example with me that today my

students promised me it would work these

are virus assembled nanowires when you

shine light on them you can start seeing

them bubbling in this case you’re seeing

oxygen bubbles come out and basically by

controlling the jeans you can control

multiple materials to improve your

device performance the last example our

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

basically and use as a way of getting

electrons through the device and what we

found is through genetic engineering we

can actually increase the efficiencies

of these solar cells to to record

numbers for these types of

dye-sensitized systems and I brought one

of those as well that that you can play

around with outside afterwards so this

is a virus based solar cell through

evolution and selection we took it from

basically an eight percent efficiency

solar cell to eleven percent efficiency

solar cell so I hope that I’ve convinced

you that that there’s a lot of great

interesting things to be learned about

how nature makes materials and taking it

the next step to see if you can you can

force or whether you can take advantage

of how nature makes materials to make

things that that nature hasn’t yet

dreamed of making thank you

you