A spider's web is more
than just a spider's house.
This homemade, glistening material
has some spidey strength of its own.
Spider silk is tougher than Kevlar,
more flexible than nylon,
and thinner than a single strand of human hair,
making this supermaterial one of the strongest materials
in the world, biological or manmade.
And the combination of its strength and stretch
is exactly why scientists
are obsessed with cloning spider silk.
Now, there are seven types of spider silks,
but one has caught the eye
of scientists worldwide.
Randy Lewis: It's called dragline silk,
and it's the silk that they use to make
the framework of the web and the radii,
but they also, the reason it's called dragline
is that whenever they walk they leave the silk behind.
Narrator: This is Randy Lewis,
a molecular biologist at Utah State University
known for his pioneering efforts
in producing synthetic spider silk.
Now, Lewis and other scientists
say that silk is so strong,
it could be used in advances in artificial ligaments,
surgical sutures, and hernia meshes.
While other spider threads rely on one protein,
this one combines two,
with protein structures that build and lock onto each other,
almost like Legos.
This builds up the strand's strength and elasticity,
with bonds so strong even water can't penetrate them.
But you can't just take these silks from spiders.
Spiders are actually notoriously
bad at spinning their own threads.
They'll make strands that are inconsistent in diameter,
making them fine for this,
but not necessarily for this.
So Lewis and his team have had to turn to other methods.
Lewis: In terms of the spider silk protein,
we've got to find a cheap way to make it.
Narrator: Randy and his team took the spider silk gene
from their lab and decided to transfer it
into other organisms to see if protein production
could happen through other processes.
Lewis: Now, we started with bacteria,
because they're easy, they're fast.
Narrator: But researchers also tried to see
if they could grow it in plants like alfalfa
or insert the spider-silk-laden bacteria into goats.
Lewis: We moved the gene from our bacteria into goats,
and so they produce the spider silk protein in the milk,
and we collect the milk
and purify the spider silk protein from that.
Narrator: But the most efficient method they discovered?
Silkworms.
This method is still being used today,
with Lewis' lab both making
and spinning synthetic spider thread.
The next step is actually using it.
Lewis: We know that that certainly has possibilities
for artificial ligaments and artificial tendons,
because we know that we can make material right now
that's stronger than a human tendon for the same diameter.
Narrator: And it's not just tendons and ligaments.
Researchers have been experimenting with using
spider threads to reconnect severed nerves.
Traditionally, nerve repair is often limited
to gaps smaller than three centimeters,
using transplanted nerves or hollow conduits
to fill the space.
But spider silk can actually extend beyond
that length without becoming brittle and breaking.
Christine Radtke: This makes it very, very special.
Narrator: This is Christine Radtke,
who led a team of researchers over at
Hannover Medical School in Germany to develop a technique
using spider silk to connect damaged nerves.
Radtke: We had a gap in a nerve,
and in that gap we put in
longitudinal direction of a spider silk,
and we could see nerve regeneration over that gap.
Narrator: The team tested this method on sheep,
since they found that sheep's nerves closely
replicated those of humans, and they discovered
that the nerve cells would use the spider silk
almost like a trellis, growing along the thread.
Radtke: And on spider silk, they go crazy.
They proliferate.
That's exactly what we need for repair.
For regeneration.
So, if the extremity is moving, it doesn't rupture,
and on the other side, it's flexible as well,
and that's exactly what we need.
So it's a perfect material,
and we only could find that in nature.
Narrator: And then there's the recovery period.
Research has shown that the human cells
won't reject the spider silk,
and Radtke's team has found that silk can simply
dissolve into the human body after doing its job.
Radtke: So, the spider silk will be there
for a certain time,
and afterwards it will be degraded by microfibers,
so it will disappear.
Narrator: So with all this possibility, the question is:
What has been done with these silks?
Lewis: Absolutely nothing!
Narrator: There's still a lot of hesitation
around spider silks.
And the Food and Drug Administration still have yet
to approve the biomaterial for use
in the medical industry and beyond.
Some simply see it as risky.
Radtke: The next step will be
that we have to do clinical studies
and obviously as well financing.
Narrator: Spider silk is also extremely
expensive to make, so businesses would need
to discover another cheaper way to make it.
So, all this research, and then nothing?
Lewis: I think the whole idea of being able to
design a fiber with properties that we want it to have
rather than just taking what the spiders have given us
so far is also a big deal.
Narrator: And that work is still happening.
Other startups are looking to use the silk
in medicinal fields, military applications,
and even as biofabrics for things like bulletproof clothes.
So scientists can continue to learn from cloning
spider silks and designing the proteins
knowing that spider silks
do hold a promising place in the future.