April 10, 2025 • 25 mins
Fiorenzo Omenetto is a professor of biomedical engineering at Tufts University and the director of Silklab. Fiorenzo's problem is this: How do you turn a material people have been using for thousands of years into useful, cutting edge tools that improve everything from vaccine delivery to food waste?
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:15):
Pushkin. Today's show has some classic plain vanilla innovation, as
people playing with lasers and trying to make new kinds
of materials, people trying to improve vaccine delivery, people trying
to reduce food waste. But today's show also has some
(00:35):
kinds of innovation that we don't hear so much about,
like thousands of years of selective breeding of caterpillars, also
millions of years of caterpillar evolution that have created this
amazing super thin, super strong fiber that the caterpillar spins
into a cocoon basically by doing three D printing, Which
(00:58):
does it even count as innovation if a caterpillar does it?
I'm going to go with yes. For the purposes of
this shoe, of this moment, I'm going to say yes.
I'm Jacob Goldstein, and this is What's Your Problem, the
show where I talk to people who are trying to
make technological progress. My guest today is Fiorenzo Omenetto. He's
(01:21):
a professor of biomedical engineering at Tufts University and he
studies silk. Fiorenzo's problem is this, how do you turn
a fabric people have been using for thousands of years
into useful cutting edge materials. Fiorenzo's background is in physics
and optics, but he runs what's known as the Silk Lab.
(01:42):
He and his colleagues take natural silk, isolate the key protein,
and use it to create new useful stuff. Fiorenzo got
into silk one day about twenty years ago when he
ran into his colleague David Kaplan in the hall at work.
David handed him something that looked like a little piece
of plastic, but that turned out, of course to be silk.
Speaker 2 (02:03):
So David is responsible for me, for me working with silk.
So my background is really technical, and I come from
material science laser physics, and with this background, I join
a biomedical engineering department, which is already sort of like
a leap of faith.
Speaker 1 (02:19):
If you will, you're you're kind of a weirdo there, Yeah,
I suppose, I suppose let's just stay orthogonal. Yes, that's
a h I've been orthogonal in a lot of settings.
Speaker 2 (02:33):
I suppose, right.
Speaker 1 (02:34):
Orthogonal too, orthogonal to a lot of sex.
Speaker 2 (02:37):
Sorry, yes, orthogonal too. Yes, And we had a conversation
in the hall. David's a tissue engineer, and and then
the premise of tisser engineering is finding biocompatible materials that
can enter the body and can serve as scaffolding for
cells to rebuild our tissues. So we're in the hallway
(02:57):
and he presents me with this like little piece of
classic that was supposed to be a tissue engineering scaffold
for a replacement CORNEA. Okay, but the cells weren't able
to grow inside of it, And so said, can you
can you maybe use your lasers to poke some holes
in it so that the cells can grow in and
then if they permeate this, then they can regrow the
corn it. So I took this this piece of plastic,
(03:19):
I took it to the lab and I put a
laser beam on it, and I lost the laser beam.
When I put the laser beam on this little piece
of plastic, I couldn't see the spot and an and
to an optics geek like me, that means that the
surface is incredibly smooth. It means that there's no scattering
and this and this surface is very beautiful from an
optical perspective.
Speaker 1 (03:40):
When you say you lost it, you mean it just
kind of disappeared on there, like you didn't see a
little red dot or whatever.
Speaker 2 (03:45):
Is that?
Speaker 1 (03:46):
What that means.
Speaker 2 (03:47):
That is exactly what it means. And generally you see
the red dot when you have when you have some
roughness that gives you the scattering and makes the spot visible.
And so that one question led to the other, and
we started doing optics with it, and we started doing
like these holograms and materials out of what turned out
to be silk.
Speaker 1 (04:03):
Right, what what are your first ideas? So you realize, oh,
this is silk, and weirdly it has this property of
being crazy smooth. What do you think about doing with it?
Once you realize that.
Speaker 2 (04:14):
You basically have a construction material that starts from water
in a protein that floats around, and then you can
turn it into multiple forms, so film, sponges, blocks, what
have you. You can print it, you can spray it,
you can predprinted, painted, et cetera. And all of this
is in a format that is edible, implantable, and that,
(04:39):
as we discovered as we went along, that also stabilizes
biological activity and you know, acts as a preservative for
molecules that otherwise need to be refrigerated. Oh. Interest, So
this is where things diverged.
Speaker 1 (04:52):
And there are a lot of basically biological applications medical
and sort of medical adjacent applications because this benign, naturally
occurring protein that is the essence of silk, has these
wonderful properties.
Speaker 2 (05:06):
That's right, That's right, And so we started doing we
started doing things for fun. I mean, we started looking
at the optical properties. We started doing optical devices, and
we started doing imprinting, and we looked at where were
the limits of fabrication that we could push.
Speaker 1 (05:20):
How much cool and useful stuff could you make with silk?
Speaker 2 (05:23):
Basically, that's right. And there's also you know, the wow factor,
because you know, it's a very different format than having
silk that looks like this.
Speaker 1 (05:31):
Yes, now you're holding up a silk scarf.
Speaker 2 (05:33):
Now I'm holding up a silk carf. Yes.
Speaker 1 (05:37):
So let's I want to get to a lot of
the applications that have come out of your work. But
before we do that, I just want to talk about
silk for a few minutes, because it's interesting and it's
sort of the core of why you've been working on
this for almost twenty years, right, So, like, why is
silk so amazing?
Speaker 2 (06:01):
I wish I had like a like a one liner.
Speaker 1 (06:04):
Let's talk about it. Let's just talk about silk tell
me about silk.
Speaker 2 (06:08):
So silk, particularly textile silk, is one of the most
engineered natural materials that there is. Legend has it, you know,
it wasn't quite the apple that fell from the tree,
but it was the cocoon that fell from the tree
while a princess was drinking tea. Yes, and then this
lustrous fiber came off.
Speaker 1 (06:27):
This is in China, more than a thousand years ago.
I mean, we know there's the myth, but we know
that they've been making silk in China for more than
a thousand years certainly, right.
Speaker 2 (06:36):
But most importantly, I think that the thing that is
unappreciated is that the bombax morey caterpillar has been domesticated
for all of this time, with all the while the
intrigue of the you know, of my line of silkworms
produces a very fine silk. This other line of silkworms
doesn't do as well. And so the finest products that
you can get you get from a certain farm. This
(06:58):
was all the intrigue of optimizing, right.
Speaker 1 (07:02):
I mean, it's innovation, right, There are literally centuries of innovation,
and just to just to say for I think most
people know, but like there's a particular worm.
Speaker 2 (07:13):
Right.
Speaker 1 (07:13):
The silkworm is whatever the larval form of a particular moth, right,
if I'm getting that right. And it spins its cocoon
out of this material that is basically silk or was
what they used to make silk, right, And it only
eats the mulberry tree bark or something right right, prefers
the mulberry tree bark.
Speaker 2 (07:34):
A majestically picky eater. Yes, And it's remarkable and.
Speaker 1 (07:40):
As I mean, as I understand it, the optimization it's
actually they have through you know, breeding basically over time,
have made it so that the moths make more silkworms.
You get more silkworms, you get more silk, you know,
more quickly. Right, So it already comes to us as
this incredibly optimized thing. There's nature has done a tremendous
(08:01):
amount of work, and then people in China for a
thousand years have done more.
Speaker 2 (08:04):
Right, that's right, And then it propagated all over the place.
And it's really very technical. And so this agricultural crop
the kids textiles that are very prized for their luster,
for their look, for their thermal properties, for their durability, right.
Speaker 1 (08:19):
Like great long underwear, right high right ers nice scar.
Speaker 2 (08:24):
Absolutely, there's like all sorts of all sorts of beautiful things.
But they come they come in this format. I mean,
and I'm holding up a cocoon right now, they come
in this format.
Speaker 1 (08:32):
Is there? Is that a real cocoon? Or is that
like a model?
Speaker 2 (08:36):
No? No, no, this is a real cocoon.
Speaker 1 (08:38):
Wait, hold it up again. So it's let's talk about it.
Speaker 2 (08:41):
Let me find here we go, let me find one.
Speaker 1 (08:44):
That is how many cocoons do you have on your desk?
You just put one down and picked up another one?
Speaker 2 (08:48):
We have We are full of cocoons. So you're holding it.
Speaker 1 (08:52):
Okay, tell me about it. It's white, it's white, white, white, right,
it's snow white. It looks on the picture.
Speaker 2 (08:58):
So it's a snow wide, giant giant, a giant bean.
Speaker 1 (09:06):
Yeah, it's bigger than a bean. I'm trying to think,
what is that size? Like if you smushed a ping
pong ball into an oblong shape, would it be about
that size?
Speaker 2 (09:14):
How about that size?
Speaker 1 (09:15):
And you're holding it by a thread? Is that a
little silken thread that you're holding up? I can't even
see it. It's invisible.
Speaker 2 (09:21):
I'm trying to figure out there you can kind of
see it now maybe.
Speaker 1 (09:25):
I mean it's cool that it's invisible.
Speaker 2 (09:27):
It's magic.
Speaker 1 (09:28):
It's like it's like a spider web, right, in fact,
spider webs. In fact, spider webs are quite similar. But
it's hard to read spiders, right, that's what I read.
Speaker 2 (09:37):
So spiders cannot be domesticated, but but caterpillars can. There
are billions of these cocoons, Yeah, there are, there are.
There are a lot, a lot a lot of these cocoons.
But the remarkable thing is that each cocoon is an
engineering wonder. Because if you take the cocoon and you
unwind it, so you wash the glue away that the
worms used to keep it together, or the caterpillars used
(09:58):
to keep this together, and you pull, you have almost
one kilometer of an interrupted thread, so ten micron thread
that is composed by two silk fibers that are held together.
The ten microns means about it ten to the diameter
of your hair. Each fiber is composed by two individual
fibers that are held together by that glue that I
mentioned before. And because there are two spinning glands in
(10:19):
the caterpillar and then and then all held together in
this non woven format that is extremely resilient. It's something
that you just can't tear and this and think there's
no weave in here. It's just the worm that is
building up layer by layer by layer as it's building
this cocoon.
Speaker 1 (10:35):
It's like additive manufacturing. It's like three D printing.
Speaker 2 (10:38):
Yeah, it is absolutely that this is a biological three
D printer. It's a filamentary three D printer that builds
a cocoon from the inside to I.
Speaker 1 (10:47):
Mean, yeah, yeah, the caterpillars on the inside doing it.
So okay, So there's this incredible natural context to begin
with this incredible thing that the silkworm does. And then
on top of that, we have the kind of innovation
and optimization of whatever one thousand plus years of farming
and you know, commercial and then you kind of walk
(11:11):
onto the stage and you realize, oh, this stuff is
really cool and you start playing with it. And let's
talk about some of the some of the things that
have come out of it. Right, it's not purely academic work.
There have been commercial spin offs.
Speaker 2 (11:27):
So the important qualities of the of the material fabrication
process that open up an endless kit of material wonder
are the fact, the end formats of material you can eat,
you can implant in the body. You can mix things
into this glass of water and silk, mix things that
are delicate biologically, and you can preserve them, and then
(11:49):
you can control the degradation of the materials. You can
dip them in water and they dissolve immediately, or you
can dip in water and they'll stay put for years.
Speaker 1 (11:58):
Just depending on how you build it.
Speaker 2 (12:00):
Essentially, how you put the proteins together. Imagine a bunch
of a bunch of little lego pieces that are floating around,
and depending on how hard you press it, the material
lasts more or less. And you can control, you know,
the sizes of the bricks that you put in the
solution and how they're pressed together. And so to a
material scientist, having these functional aspects in the material just
(12:21):
is mind blowing because you can start really imagining. What
if you look at all the materials that surround you
and you start saying, well, what if I could plant
this in my garden, What if I could eat it?
What if I could put biological communicators inside of what
if I could put chemistries inside here that are very
difficult to put in by other means, so then this
(12:43):
just opens up a world of craziness, and so.
Speaker 1 (12:48):
Of the delightful craziness, right, good craziness.
Speaker 2 (12:51):
I think the thing that I still find myself very
surprised by is that after now nearly twenty years of
working with this material, I think, I think I'm still
as excited about the potential of this material as I
was on day one.
Speaker 1 (13:08):
Still to come on the show. Using silk to find
a better way to deliver vaccines, and also using silk
to help preserve fruits and vegetables, also more things to
do with silk. What's something that is in the world
(13:30):
based on your work.
Speaker 2 (13:32):
One of the companies that is called Vaccess is now
using silk based technology to do micro needle patches with
therapy that doesn't need to be refrigerated. So I imagine
just putting on a band aid rather than going took
place to get an injection and not having to worry
about storing your therapy in the fridge.
Speaker 1 (13:50):
Particularly important in the developing world. Right we take the
cold chain for granted here, and yes it's a hassle
to go to the pharmacy and get a shot, but
like there are parts of the world where like, you know,
the vaccine has to be called from the time it's
made until it goes into your arm. Essentially, Yes, so
it has to be in a truck and a ship
and everywhere. It has to stay cold, and you have
to have power, and there are big parts of the
(14:10):
world where that just doesn't exist, right, So it actually
is a real problem on a global scale.
Speaker 2 (14:16):
I would argue also that it potentially could become even
more profitable. I believe that there's a lot of opportunities
still out there for these classes of material to be
to generate an incredible amount of revenue.
Speaker 1 (14:27):
I mean, do you mean just because it's cheaper, because
if you don't have to keep it cold, it's more efficient,
or like what makes you think of or just because
people prefer what makes like I'm interested? I just what
makes you think of that? Here in the conversation.
Speaker 2 (14:39):
I think that the functional surprise is what makes this
an appealing product, and it makes it economically viable. I
think that having trying to substitute materials one for one
is very difficult given the sophistication of what we have today.
But I think that if your material manages to do
something unexpected that brings more value to a.
Speaker 1 (14:59):
Person saying it's not just not the cold chain, it's
you don't have to get a shot, you just put
this sticker on your arm.
Speaker 2 (15:04):
It's a collection of things. And so the jury is
out of whether this is true or not. I think
the opportunity is big, but I see also that it
requires an enormous amount of dedication and it requires entrepreneurship.
Speaker 1 (15:16):
And that that side of it is clearly not not
your side. It seems as you're talking about.
Speaker 2 (15:20):
It, Well, it can't be.
Speaker 1 (15:22):
There are there are professors who also start companies.
Speaker 2 (15:25):
Yes, but I think that I'm a big believer of
the fact that you have to dedicate your full attention
to something to bring it at ats maximum levels.
Speaker 1 (15:33):
So there's there's another thing that that people are developing
based on on the work on your work and your
colleagues work for for for vocal vocal cord, right what
they call it vocal folds, but it's basically vocal cords.
Tell me about that.
Speaker 2 (15:49):
So for example, one of the one of the examples
is that in certain cases, when you lose mechanical properties
in your vocal fold, your your vocal cords are not
able to vibrate anymore and you and you lose your
capacity to speak. And so one of the one of
the strategies would be to restore the strength of the
vocal fold so that you give mechanical ford it to
(16:09):
to that. So we studied this formulation where imagine that
you have a dense injectable jello that comes and stays
and stays put in some place and mixes with your
native tissue and makes it more fur I see.
Speaker 1 (16:23):
Okay.
Speaker 2 (16:23):
So one of the companies that took the gel technology
out studied this and they came up with an injectable
format that restores the mechanical properties of the fold and
actually gives the capacity to the patients to speak. Again.
This is an FDA approved therapy, so it works. So
it worked. So this is something that you can get today.
Speaker 1 (16:46):
Food preservation, somebody's working on using some silk based technology
to make fresh food stay good longer. Tell me about that.
Speaker 2 (16:53):
So it turns out that the silk liquid is very
good at coating objects. And if you take, for example,
of strawberry and you dip it in water and silk
so coats the strawberry with a thin layer of material
that acts as a fruit preservative. And it's very effective
to prolong the shelf life at room temperature of materials
(17:13):
by a week or a couple of weeks. And then
I guess it depends on what you use it on,
and every food as its own story. At the time,
we in the lab, we tried it on bananas and
on strawberries, and we saw that at room temperature we
could keep bananas and strawberries fresh for a extra week,
ten days or something like that.
Speaker 1 (17:32):
And so where is that sort of product in the
arc of commercialization, this silk based fruit, you know, preservative.
Speaker 2 (17:40):
Honestly, I think that this is a question for the
company itself, but I know that some product has been
successfully applied to leafy greens, and I think that the
that the use case there is the ability to enhance logistics, give.
Speaker 1 (17:55):
You more time to get the greens from the farm
to the table.
Speaker 2 (17:59):
Exactly, from from point A to point B and without refrigeration,
which is a big deal.
Speaker 1 (18:03):
Okay, tell me what you're working on.
Speaker 2 (18:05):
Now. What are we working on now? We're working on
sense a lot. We have friends that design proteins that
are very very sensitive and very very specific. So there
are possibilities of giving formats to say, things for example,
that detect hormones. So one of the things that we
did recently was to make an ink with a design
(18:26):
or a protein if you will, that was very sensitive
and very specific to human estrogen receptor two, which is
one of the one of the hormones that is responsible
for breast cancer. So you start imagining things like painting
and the inside of a bra so that you have
a monitor of recurrence for example, of or you have
a monitor for breast cancer. We did the same thing
(18:48):
with toxins like bochulin and hepatitis beat, and so all
of these things become very powerful when you have them
in these different formats that are very unexpected.
Speaker 1 (18:59):
So the core thing you have ultimately with the silk
is this benign stabilizing force, Right, That's the thing you're
flying in all these different detection settings. Is that, right,
a way to take whatever essentially detectors, these protein detectors
that might whatever decompose in other settings. You're stabilizing them
(19:24):
in a very kind of safe, benign way. That seems
like the core thing that is happening in all these
different use cases you're describing is that, right, That is true.
Speaker 2 (19:32):
But the other thing that is very important is that
you stabilize these and that's the functional part, but then
you shape it, and the shapes are very very technological.
So the other thing that we're working on that is
very exciting is how to control silk and the nanoscale
and actually have these things very precisely localized, and that
can lead to really nice, nice interfaces with for example,
(19:52):
with semiconductors.
Speaker 1 (19:54):
Say a little more about that one.
Speaker 2 (19:57):
So we had we had a recent paper where we
showed it in a transistor. We can put a thin
layer of silk within the transistor and we can use
the state of silk to change the way that the
transistors switches.
Speaker 1 (20:10):
Huh, switches, which is the fundamental thing a transistor does,
goes from on off.
Speaker 2 (20:15):
Basically, that's right. So so if you can, if you
could imagine this multiplied by a Tralian transistors, Yeah, it
would be a very powerful way to sense things, for example,
or to silk or channelized things. Yeah, why not.
Speaker 1 (20:31):
So just to land the main part of the conversation here,
you've been working with silk for almost twenty years. Like
if you sort of zoom out and look at the
big picture arc of your work, what do you come away.
Speaker 2 (20:45):
With there are two two main things. I think one
is a thing that comes from wonder and surprise. And
I think that the more you look at things around
you and you and you interpret and you're amazed by
the things around you, the more you learn about them,
the more you the more inspired you are, I would say.
(21:05):
And then the other thing that I would say is
that natural systems, natural materials have an unbelievable degree of sophistication,
of hierarchical sophistication. And by that I mean they are
so exquisitely engineered at all scales to provide very simultaneous
(21:25):
functions that are technologically incredibly relevant, you know. So like
the way that they manage energy, the way that they
repel infection, the way that they are super hydrophobic, the
way that they're resilient, way by being ultra light, their
ability to keep warm and to keep cold depending on
the need. It's just it's just an endless the way
(21:47):
that they self heal, it's like an endless stream of
things that is incredible. Nature has a lot of ideas
to do really smart things, to do really meaningful things,
to do profound things, and to do very profitable things.
Speaker 1 (22:03):
We'll be back in a minute with the light ground.
Let's finish with the lightning round. What's one thing about
lasers that you wish more people understood.
Speaker 2 (22:21):
How profoundly different they are from a light bulb?
Speaker 1 (22:24):
Huh, just tay a little more. I feel like I
should know that better. Tell me.
Speaker 2 (22:30):
Lasers are light and we kind of take for granted
that this light travels in a travels in the line
and gives you a spot. And they're the same. It's
the same light that you get from a light bulb,
except for the light from the light bulb goes all
over the place where the laser is directional. And that
fact that the laser is directional is is amazing material
magic why it gives it order. So it's very very
(22:56):
ordered light. You take something that is chaotic and you
make it keep step with time and with space. Wow.
And it's very important because it's at the basis of
a lot of things, including self driving cars that don't
smash it two into one another, for example, in some
in some cases.
Speaker 1 (23:12):
What's your favorite use of a laser in fiction, in
a movie, in a book.
Speaker 2 (23:17):
Oh, obviously laser being on sharks, Austin power. It's I mean,
it's er evils, it is doctor Good.
Speaker 1 (23:27):
So, as I understand that you were an Oppenheimer fellow
at Los Alamos, I was, what do you think of
the movie Oppenheimer?
Speaker 2 (23:35):
Oh gosh, how much time do we have? This is
not a lightning question. It was it was if I
liked it.
Speaker 1 (23:44):
It's complicated when you were at Less almost twenty years ago,
like the get you catch any Manhattan Project vibes? Or
was it just kind of a relic?
Speaker 2 (23:52):
No. I think that it's very present, that the history
is palpable in in the lab. And I think that
one of one of the best things is to go
to the museum and see their guest books and see
and see what people write on the guest book after
they've gone through the whole story of the Manhattan Project,
and it's very The range of comments is astounding. It's
(24:13):
from you know, international Atomic Agency officers to senators, to
a high school football team to Japanese visitors, you know,
and and it was at least very much in the
culture of the lab. And I think that there's a
I can't see how how it wouldn't be.
Speaker 1 (24:30):
Yeah, true that you wrote a vespa. True, you still
write a vespa not often.
Speaker 2 (24:38):
I do my own one, but it's gathering a lot
of dust.
Speaker 1 (24:42):
You think vespas are overrated or underrated?
Speaker 2 (24:45):
Ah, that's that's I'm not gonna. I'm not gonna. I'm
not gonna even comment on that. I think they I
think I think they look great.
Speaker 1 (24:57):
You runzo Omenetto runs the Silk Lab at Tufts University.
Today's show was produced by Gabriel Hunter Cheng. It was
edited by Lyddy jeene Kott and engine heared by Sarah Bruguer.
You can email us at problem at Pushkin dot fm.
I'm Jacob Bothstein, and we'll be back next week with
another episode of What's Your Problem.
Pushkin. Today's show has some classic plain vanilla innovation, as
people playing with lasers and trying to make new kinds
of materials, people trying to improve vaccine delivery, people trying
to reduce food waste. But today's show also has some
(00:35):
kinds of innovation that we don't hear so much about,
like thousands of years of selective breeding of caterpillars, also
millions of years of caterpillar evolution that have created this
amazing super thin, super strong fiber that the caterpillar spins
into a cocoon basically by doing three D printing, Which
(00:58):
does it even count as innovation if a caterpillar does it?
I'm going to go with yes. For the purposes of
this shoe, of this moment, I'm going to say yes.
I'm Jacob Goldstein, and this is What's Your Problem, the
show where I talk to people who are trying to
make technological progress. My guest today is Fiorenzo Omenetto. He's
(01:21):
a professor of biomedical engineering at Tufts University and he
studies silk. Fiorenzo's problem is this, how do you turn
a fabric people have been using for thousands of years
into useful cutting edge materials. Fiorenzo's background is in physics
and optics, but he runs what's known as the Silk Lab.
(01:42):
He and his colleagues take natural silk, isolate the key protein,
and use it to create new useful stuff. Fiorenzo got
into silk one day about twenty years ago when he
ran into his colleague David Kaplan in the hall at work.
David handed him something that looked like a little piece
of plastic, but that turned out, of course to be silk.
Speaker 2 (02:03):
So David is responsible for me, for me working with silk.
So my background is really technical, and I come from
material science laser physics, and with this background, I join
a biomedical engineering department, which is already sort of like
a leap of faith.
Speaker 1 (02:19):
If you will, you're you're kind of a weirdo there, Yeah,
I suppose, I suppose let's just stay orthogonal. Yes, that's
a h I've been orthogonal in a lot of settings.
Speaker 2 (02:33):
I suppose, right.
Speaker 1 (02:34):
Orthogonal too, orthogonal to a lot of sex.
Speaker 2 (02:37):
Sorry, yes, orthogonal too. Yes, And we had a conversation
in the hall. David's a tissue engineer, and and then
the premise of tisser engineering is finding biocompatible materials that
can enter the body and can serve as scaffolding for
cells to rebuild our tissues. So we're in the hallway
(02:57):
and he presents me with this like little piece of
classic that was supposed to be a tissue engineering scaffold
for a replacement CORNEA. Okay, but the cells weren't able
to grow inside of it, And so said, can you
can you maybe use your lasers to poke some holes
in it so that the cells can grow in and
then if they permeate this, then they can regrow the
corn it. So I took this this piece of plastic,
(03:19):
I took it to the lab and I put a
laser beam on it, and I lost the laser beam.
When I put the laser beam on this little piece
of plastic, I couldn't see the spot and an and
to an optics geek like me, that means that the
surface is incredibly smooth. It means that there's no scattering
and this and this surface is very beautiful from an
optical perspective.
Speaker 1 (03:40):
When you say you lost it, you mean it just
kind of disappeared on there, like you didn't see a
little red dot or whatever.
Speaker 2 (03:45):
Is that?
Speaker 1 (03:46):
What that means.
Speaker 2 (03:47):
That is exactly what it means. And generally you see
the red dot when you have when you have some
roughness that gives you the scattering and makes the spot visible.
And so that one question led to the other, and
we started doing optics with it, and we started doing
like these holograms and materials out of what turned out
to be silk.
Speaker 1 (04:03):
Right, what what are your first ideas? So you realize, oh,
this is silk, and weirdly it has this property of
being crazy smooth. What do you think about doing with it?
Once you realize that.
Speaker 2 (04:14):
You basically have a construction material that starts from water
in a protein that floats around, and then you can
turn it into multiple forms, so film, sponges, blocks, what
have you. You can print it, you can spray it,
you can predprinted, painted, et cetera. And all of this
is in a format that is edible, implantable, and that,
(04:39):
as we discovered as we went along, that also stabilizes
biological activity and you know, acts as a preservative for
molecules that otherwise need to be refrigerated. Oh. Interest, So
this is where things diverged.
Speaker 1 (04:52):
And there are a lot of basically biological applications medical
and sort of medical adjacent applications because this benign, naturally
occurring protein that is the essence of silk, has these
wonderful properties.
Speaker 2 (05:06):
That's right, That's right, And so we started doing we
started doing things for fun. I mean, we started looking
at the optical properties. We started doing optical devices, and
we started doing imprinting, and we looked at where were
the limits of fabrication that we could push.
Speaker 1 (05:20):
How much cool and useful stuff could you make with silk?
Speaker 2 (05:23):
Basically, that's right. And there's also you know, the wow factor,
because you know, it's a very different format than having
silk that looks like this.
Speaker 1 (05:31):
Yes, now you're holding up a silk scarf.
Speaker 2 (05:33):
Now I'm holding up a silk carf. Yes.
Speaker 1 (05:37):
So let's I want to get to a lot of
the applications that have come out of your work. But
before we do that, I just want to talk about
silk for a few minutes, because it's interesting and it's
sort of the core of why you've been working on
this for almost twenty years, right, So, like, why is
silk so amazing?
Speaker 2 (06:01):
I wish I had like a like a one liner.
Speaker 1 (06:04):
Let's talk about it. Let's just talk about silk tell
me about silk.
Speaker 2 (06:08):
So silk, particularly textile silk, is one of the most
engineered natural materials that there is. Legend has it, you know,
it wasn't quite the apple that fell from the tree,
but it was the cocoon that fell from the tree
while a princess was drinking tea. Yes, and then this
lustrous fiber came off.
Speaker 1 (06:27):
This is in China, more than a thousand years ago.
I mean, we know there's the myth, but we know
that they've been making silk in China for more than
a thousand years certainly, right.
Speaker 2 (06:36):
But most importantly, I think that the thing that is
unappreciated is that the bombax morey caterpillar has been domesticated
for all of this time, with all the while the
intrigue of the you know, of my line of silkworms
produces a very fine silk. This other line of silkworms
doesn't do as well. And so the finest products that
you can get you get from a certain farm. This
(06:58):
was all the intrigue of optimizing, right.
Speaker 1 (07:02):
I mean, it's innovation, right, There are literally centuries of innovation,
and just to just to say for I think most
people know, but like there's a particular worm.
Speaker 2 (07:13):
Right.
Speaker 1 (07:13):
The silkworm is whatever the larval form of a particular moth, right,
if I'm getting that right. And it spins its cocoon
out of this material that is basically silk or was
what they used to make silk, right, And it only
eats the mulberry tree bark or something right right, prefers
the mulberry tree bark.
Speaker 2 (07:34):
A majestically picky eater. Yes, And it's remarkable and.
Speaker 1 (07:40):
As I mean, as I understand it, the optimization it's
actually they have through you know, breeding basically over time,
have made it so that the moths make more silkworms.
You get more silkworms, you get more silk, you know,
more quickly. Right, So it already comes to us as
this incredibly optimized thing. There's nature has done a tremendous
(08:01):
amount of work, and then people in China for a
thousand years have done more.
Speaker 2 (08:04):
Right, that's right, And then it propagated all over the place.
And it's really very technical. And so this agricultural crop
the kids textiles that are very prized for their luster,
for their look, for their thermal properties, for their durability, right.
Speaker 1 (08:19):
Like great long underwear, right high right ers nice scar.
Speaker 2 (08:24):
Absolutely, there's like all sorts of all sorts of beautiful things.
But they come they come in this format. I mean,
and I'm holding up a cocoon right now, they come
in this format.
Speaker 1 (08:32):
Is there? Is that a real cocoon? Or is that
like a model?
Speaker 2 (08:36):
No? No, no, this is a real cocoon.
Speaker 1 (08:38):
Wait, hold it up again. So it's let's talk about it.
Speaker 2 (08:41):
Let me find here we go, let me find one.
Speaker 1 (08:44):
That is how many cocoons do you have on your desk?
You just put one down and picked up another one?
Speaker 2 (08:48):
We have We are full of cocoons. So you're holding it.
Speaker 1 (08:52):
Okay, tell me about it. It's white, it's white, white, white, right,
it's snow white. It looks on the picture.
Speaker 2 (08:58):
So it's a snow wide, giant giant, a giant bean.
Speaker 1 (09:06):
Yeah, it's bigger than a bean. I'm trying to think,
what is that size? Like if you smushed a ping
pong ball into an oblong shape, would it be about
that size?
Speaker 2 (09:14):
How about that size?
Speaker 1 (09:15):
And you're holding it by a thread? Is that a
little silken thread that you're holding up? I can't even
see it. It's invisible.
Speaker 2 (09:21):
I'm trying to figure out there you can kind of
see it now maybe.
Speaker 1 (09:25):
I mean it's cool that it's invisible.
Speaker 2 (09:27):
It's magic.
Speaker 1 (09:28):
It's like it's like a spider web, right, in fact,
spider webs. In fact, spider webs are quite similar. But
it's hard to read spiders, right, that's what I read.
Speaker 2 (09:37):
So spiders cannot be domesticated, but but caterpillars can. There
are billions of these cocoons, Yeah, there are, there are.
There are a lot, a lot a lot of these cocoons.
But the remarkable thing is that each cocoon is an
engineering wonder. Because if you take the cocoon and you
unwind it, so you wash the glue away that the
worms used to keep it together, or the caterpillars used
(09:58):
to keep this together, and you pull, you have almost
one kilometer of an interrupted thread, so ten micron thread
that is composed by two silk fibers that are held together.
The ten microns means about it ten to the diameter
of your hair. Each fiber is composed by two individual
fibers that are held together by that glue that I
mentioned before. And because there are two spinning glands in
(10:19):
the caterpillar and then and then all held together in
this non woven format that is extremely resilient. It's something
that you just can't tear and this and think there's
no weave in here. It's just the worm that is
building up layer by layer by layer as it's building
this cocoon.
Speaker 1 (10:35):
It's like additive manufacturing. It's like three D printing.
Speaker 2 (10:38):
Yeah, it is absolutely that this is a biological three
D printer. It's a filamentary three D printer that builds
a cocoon from the inside to I.
Speaker 1 (10:47):
Mean, yeah, yeah, the caterpillars on the inside doing it.
So okay, So there's this incredible natural context to begin
with this incredible thing that the silkworm does. And then
on top of that, we have the kind of innovation
and optimization of whatever one thousand plus years of farming
and you know, commercial and then you kind of walk
(11:11):
onto the stage and you realize, oh, this stuff is
really cool and you start playing with it. And let's
talk about some of the some of the things that
have come out of it. Right, it's not purely academic work.
There have been commercial spin offs.
Speaker 2 (11:27):
So the important qualities of the of the material fabrication
process that open up an endless kit of material wonder
are the fact, the end formats of material you can eat,
you can implant in the body. You can mix things
into this glass of water and silk, mix things that
are delicate biologically, and you can preserve them, and then
(11:49):
you can control the degradation of the materials. You can
dip them in water and they dissolve immediately, or you
can dip in water and they'll stay put for years.
Speaker 1 (11:58):
Just depending on how you build it.
Speaker 2 (12:00):
Essentially, how you put the proteins together. Imagine a bunch
of a bunch of little lego pieces that are floating around,
and depending on how hard you press it, the material
lasts more or less. And you can control, you know,
the sizes of the bricks that you put in the
solution and how they're pressed together. And so to a
material scientist, having these functional aspects in the material just
(12:21):
is mind blowing because you can start really imagining. What
if you look at all the materials that surround you
and you start saying, well, what if I could plant
this in my garden, What if I could eat it?
What if I could put biological communicators inside of what
if I could put chemistries inside here that are very
difficult to put in by other means, so then this
(12:43):
just opens up a world of craziness, and so.
Speaker 1 (12:48):
Of the delightful craziness, right, good craziness.
Speaker 2 (12:51):
I think the thing that I still find myself very
surprised by is that after now nearly twenty years of
working with this material, I think, I think I'm still
as excited about the potential of this material as I
was on day one.
Speaker 1 (13:08):
Still to come on the show. Using silk to find
a better way to deliver vaccines, and also using silk
to help preserve fruits and vegetables, also more things to
do with silk. What's something that is in the world
(13:30):
based on your work.
Speaker 2 (13:32):
One of the companies that is called Vaccess is now
using silk based technology to do micro needle patches with
therapy that doesn't need to be refrigerated. So I imagine
just putting on a band aid rather than going took
place to get an injection and not having to worry
about storing your therapy in the fridge.
Speaker 1 (13:50):
Particularly important in the developing world. Right we take the
cold chain for granted here, and yes it's a hassle
to go to the pharmacy and get a shot, but
like there are parts of the world where like, you know,
the vaccine has to be called from the time it's
made until it goes into your arm. Essentially, Yes, so
it has to be in a truck and a ship
and everywhere. It has to stay cold, and you have
to have power, and there are big parts of the
(14:10):
world where that just doesn't exist, right, So it actually
is a real problem on a global scale.
Speaker 2 (14:16):
I would argue also that it potentially could become even
more profitable. I believe that there's a lot of opportunities
still out there for these classes of material to be
to generate an incredible amount of revenue.
Speaker 1 (14:27):
I mean, do you mean just because it's cheaper, because
if you don't have to keep it cold, it's more efficient,
or like what makes you think of or just because
people prefer what makes like I'm interested? I just what
makes you think of that? Here in the conversation.
Speaker 2 (14:39):
I think that the functional surprise is what makes this
an appealing product, and it makes it economically viable. I
think that having trying to substitute materials one for one
is very difficult given the sophistication of what we have today.
But I think that if your material manages to do
something unexpected that brings more value to a.
Speaker 1 (14:59):
Person saying it's not just not the cold chain, it's
you don't have to get a shot, you just put
this sticker on your arm.
Speaker 2 (15:04):
It's a collection of things. And so the jury is
out of whether this is true or not. I think
the opportunity is big, but I see also that it
requires an enormous amount of dedication and it requires entrepreneurship.
Speaker 1 (15:16):
And that that side of it is clearly not not
your side. It seems as you're talking about.
Speaker 2 (15:20):
It, Well, it can't be.
Speaker 1 (15:22):
There are there are professors who also start companies.
Speaker 2 (15:25):
Yes, but I think that I'm a big believer of
the fact that you have to dedicate your full attention
to something to bring it at ats maximum levels.
Speaker 1 (15:33):
So there's there's another thing that that people are developing
based on on the work on your work and your
colleagues work for for for vocal vocal cord, right what
they call it vocal folds, but it's basically vocal cords.
Tell me about that.
Speaker 2 (15:49):
So for example, one of the one of the examples
is that in certain cases, when you lose mechanical properties
in your vocal fold, your your vocal cords are not
able to vibrate anymore and you and you lose your
capacity to speak. And so one of the one of
the strategies would be to restore the strength of the
vocal fold so that you give mechanical ford it to
(16:09):
to that. So we studied this formulation where imagine that
you have a dense injectable jello that comes and stays
and stays put in some place and mixes with your
native tissue and makes it more fur I see.
Speaker 1 (16:23):
Okay.
Speaker 2 (16:23):
So one of the companies that took the gel technology
out studied this and they came up with an injectable
format that restores the mechanical properties of the fold and
actually gives the capacity to the patients to speak. Again.
This is an FDA approved therapy, so it works. So
it worked. So this is something that you can get today.
Speaker 1 (16:46):
Food preservation, somebody's working on using some silk based technology
to make fresh food stay good longer. Tell me about that.
Speaker 2 (16:53):
So it turns out that the silk liquid is very
good at coating objects. And if you take, for example,
of strawberry and you dip it in water and silk
so coats the strawberry with a thin layer of material
that acts as a fruit preservative. And it's very effective
to prolong the shelf life at room temperature of materials
(17:13):
by a week or a couple of weeks. And then
I guess it depends on what you use it on,
and every food as its own story. At the time,
we in the lab, we tried it on bananas and
on strawberries, and we saw that at room temperature we
could keep bananas and strawberries fresh for a extra week,
ten days or something like that.
Speaker 1 (17:32):
And so where is that sort of product in the
arc of commercialization, this silk based fruit, you know, preservative.
Speaker 2 (17:40):
Honestly, I think that this is a question for the
company itself, but I know that some product has been
successfully applied to leafy greens, and I think that the
that the use case there is the ability to enhance logistics, give.
Speaker 1 (17:55):
You more time to get the greens from the farm
to the table.
Speaker 2 (17:59):
Exactly, from from point A to point B and without refrigeration,
which is a big deal.
Speaker 1 (18:03):
Okay, tell me what you're working on.
Speaker 2 (18:05):
Now. What are we working on now? We're working on
sense a lot. We have friends that design proteins that
are very very sensitive and very very specific. So there
are possibilities of giving formats to say, things for example,
that detect hormones. So one of the things that we
did recently was to make an ink with a design
(18:26):
or a protein if you will, that was very sensitive
and very specific to human estrogen receptor two, which is
one of the one of the hormones that is responsible
for breast cancer. So you start imagining things like painting
and the inside of a bra so that you have
a monitor of recurrence for example, of or you have
a monitor for breast cancer. We did the same thing
(18:48):
with toxins like bochulin and hepatitis beat, and so all
of these things become very powerful when you have them
in these different formats that are very unexpected.
Speaker 1 (18:59):
So the core thing you have ultimately with the silk
is this benign stabilizing force, Right, That's the thing you're
flying in all these different detection settings. Is that, right,
a way to take whatever essentially detectors, these protein detectors
that might whatever decompose in other settings. You're stabilizing them
(19:24):
in a very kind of safe, benign way. That seems
like the core thing that is happening in all these
different use cases you're describing is that, right, That is true.
Speaker 2 (19:32):
But the other thing that is very important is that
you stabilize these and that's the functional part, but then
you shape it, and the shapes are very very technological.
So the other thing that we're working on that is
very exciting is how to control silk and the nanoscale
and actually have these things very precisely localized, and that
can lead to really nice, nice interfaces with for example,
(19:52):
with semiconductors.
Speaker 1 (19:54):
Say a little more about that one.
Speaker 2 (19:57):
So we had we had a recent paper where we
showed it in a transistor. We can put a thin
layer of silk within the transistor and we can use
the state of silk to change the way that the
transistors switches.
Speaker 1 (20:10):
Huh, switches, which is the fundamental thing a transistor does,
goes from on off.
Speaker 2 (20:15):
Basically, that's right. So so if you can, if you
could imagine this multiplied by a Tralian transistors, Yeah, it
would be a very powerful way to sense things, for example,
or to silk or channelized things. Yeah, why not.
Speaker 1 (20:31):
So just to land the main part of the conversation here,
you've been working with silk for almost twenty years. Like
if you sort of zoom out and look at the
big picture arc of your work, what do you come away.
Speaker 2 (20:45):
With there are two two main things. I think one
is a thing that comes from wonder and surprise. And
I think that the more you look at things around
you and you and you interpret and you're amazed by
the things around you, the more you learn about them,
the more you the more inspired you are, I would say.
(21:05):
And then the other thing that I would say is
that natural systems, natural materials have an unbelievable degree of sophistication,
of hierarchical sophistication. And by that I mean they are
so exquisitely engineered at all scales to provide very simultaneous
(21:25):
functions that are technologically incredibly relevant, you know. So like
the way that they manage energy, the way that they
repel infection, the way that they are super hydrophobic, the
way that they're resilient, way by being ultra light, their
ability to keep warm and to keep cold depending on
the need. It's just it's just an endless the way
(21:47):
that they self heal, it's like an endless stream of
things that is incredible. Nature has a lot of ideas
to do really smart things, to do really meaningful things,
to do profound things, and to do very profitable things.
Speaker 1 (22:03):
We'll be back in a minute with the light ground.
Let's finish with the lightning round. What's one thing about
lasers that you wish more people understood.
Speaker 2 (22:21):
How profoundly different they are from a light bulb?
Speaker 1 (22:24):
Huh, just tay a little more. I feel like I
should know that better. Tell me.
Speaker 2 (22:30):
Lasers are light and we kind of take for granted
that this light travels in a travels in the line
and gives you a spot. And they're the same. It's
the same light that you get from a light bulb,
except for the light from the light bulb goes all
over the place where the laser is directional. And that
fact that the laser is directional is is amazing material
magic why it gives it order. So it's very very
(22:56):
ordered light. You take something that is chaotic and you
make it keep step with time and with space. Wow.
And it's very important because it's at the basis of
a lot of things, including self driving cars that don't
smash it two into one another, for example, in some
in some cases.
Speaker 1 (23:12):
What's your favorite use of a laser in fiction, in
a movie, in a book.
Speaker 2 (23:17):
Oh, obviously laser being on sharks, Austin power. It's I mean,
it's er evils, it is doctor Good.
Speaker 1 (23:27):
So, as I understand that you were an Oppenheimer fellow
at Los Alamos, I was, what do you think of
the movie Oppenheimer?
Speaker 2 (23:35):
Oh gosh, how much time do we have? This is
not a lightning question. It was it was if I
liked it.
Speaker 1 (23:44):
It's complicated when you were at Less almost twenty years ago,
like the get you catch any Manhattan Project vibes? Or
was it just kind of a relic?
Speaker 2 (23:52):
No. I think that it's very present, that the history
is palpable in in the lab. And I think that
one of one of the best things is to go
to the museum and see their guest books and see
and see what people write on the guest book after
they've gone through the whole story of the Manhattan Project,
and it's very The range of comments is astounding. It's
(24:13):
from you know, international Atomic Agency officers to senators, to
a high school football team to Japanese visitors, you know,
and and it was at least very much in the
culture of the lab. And I think that there's a
I can't see how how it wouldn't be.
Speaker 1 (24:30):
Yeah, true that you wrote a vespa. True, you still
write a vespa not often.
Speaker 2 (24:38):
I do my own one, but it's gathering a lot
of dust.
Speaker 1 (24:42):
You think vespas are overrated or underrated?
Speaker 2 (24:45):
Ah, that's that's I'm not gonna. I'm not gonna. I'm
not gonna even comment on that. I think they I
think I think they look great.
Speaker 1 (24:57):
You runzo Omenetto runs the Silk Lab at Tufts University.
Today's show was produced by Gabriel Hunter Cheng. It was
edited by Lyddy jeene Kott and engine heared by Sarah Bruguer.
You can email us at problem at Pushkin dot fm.
I'm Jacob Bothstein, and we'll be back next week with
another episode of What's Your Problem.
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