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