Silk, the ancient material of the future - Fiorenzo Omenetto

[Music] [Applause] Thank you. Um, I'm thrilled, thrilled to be here. Um, I'm going to talk about a new old material that still continues to amaze us and that might impact the way we think about material science, high technology, and maybe along the way also do some stuff for medicine and for global health and help reforestation. So that's kind of a bold statement. I'll tell you a little bit more.

This material actually has some traits that make it seem almost too good to be true. It's sustainable—it's a sustainable material that is processed all in water and at room temperature. And it's biodegradable with a clock, so you can watch it dissolve instantaneously in a glass of water and have it stable for years. It's edible. It's implantable in the human body without causing any immune response. It actually gets reintegrated in the body and it's technological, so it can do things that microelectronics and maybe photonics do.

And the material looks something like this. In fact, this material you see is clear and transparent. The components of this material are just water and protein. So this material is silk, and so it's kind of different from what we're used to thinking about silk.

The question is how do you reinvent something that has been around for five millennia? The process of discovery generally is inspired by nature, and so we marvel at the silkworm, the silk or that you see here spinning its fiber. The silk does a remarkable thing: it uses these two ingredients, protein and water, that are in its gland to make a material that is exceptionally tough for protection, so comparable to technical fibers like Kevlar.

In the reverse engineering process that we know about, and that we're familiar with in the textile industry, the textile industry goes and unwinds the cocoon and then weaves glamorous things. We want to know how you go from water and protein to this liquid Kevlar and to this natural Kevlar.

So, the inside is how do you actually reverse engineer this and go from cocoon to gland and get water and protein that is your starting material? This is an insight that came about two decades ago from a person that I'm very, very fortunate to work with—David Kaplan.

So we get this starting material, and the starting material is back to the basic building block. We use this to do a variety of things, like, for example, films. We take advantage of something that is very simple. The recipe to make those films is to take advantage of the fact that proteins are extremely smart at what they do. They find their way to self-assemble. So the recipe is simple: you take the silk solution, you pour it, and you wait for the protein to self-assemble. Then you detach the protein, and you get this film as the proteins find each other as the water evaporates.

But I mentioned that the film is also technological. So what does that mean? It means that you can interface it with some of the things that are typical of technology, like microelectronics and nanoscale technology. The image of the DVD here is just to illustrate a point that silk follows very, very subtle topographies of the surface, which means that it can replicate features on the nanoscale. So it would be able to replicate the information that is on the DVD, and we can store information in this film of water and protein.

So we tried something out and we wrote a message in a piece of silk, which is right here, and the message is over there. Much like in the DVD, you can read it out optically, and this requires a stable hand. So this is why I decided to do it on stage in front of a thousand people.

So let me see. As you see the film going transparently through there, and the most remarkable feat is that my hand actually stayed still long enough to do that.

Once you have these attributes of this material, then you can do a lot of things. It's actually not limited to films, and so the material can assume a lot of formats. Then you kind of go a little crazy, and so you do various optical components or you do micro prism arrays like the ones that you have, you know, the reflective tape that you have on your running shoes. Or you can do beautiful things that, if the camera can capture, you can make—you can add a third dimensionality to the film, and if the angle is right, you can actually see a hologram appear in this film of silk.

But you can do other things. You can imagine that maybe you can use a pure protein to guide light, and so we've made optical fibers. Silk is versatile, and it kind of goes beyond optics. You can think of different formats.

For instance, if you're afraid of going to the doctor and getting stuck with a needle, we do micro needle arrays. What you see there on the screen is a human hair superimposed on the needles made of silk just to give you a sense of size. You can do bigger things; you can do gears and nuts and bolts that you could buy at Whole Foods. The gears work in water as well, so think of alternative mechanical parts.

Maybe you can use that liquid Kevlar if you need something strong to replace peripheral veins, for example, or maybe an entire bone. You have here a little example of a small skull, what we call minor. But you can do things like cups, for example. If you add a little bit of gold, if you add a little bit of semiconductors, you could do sensors that stick on the surfaces of foods. You can do electronic pieces that fold and wrap, or you know if you're fashion-forward, some silk LED tattoos.

So there's versatility in, as you see, in the material formats that you can do with silk. But there are still some unique traits. I mean, why would you want to do all these things in silk for real?

I mentioned it briefly at the beginning: the protein is biodegradable and biocompatible. You see here a picture of a tissue section. So what does that mean, that it's biodegradable and compatible? You can implant it in the body without needing to retrieve what is implanted, which means that all the devices that you've seen before, in all the formats, in principle can be implanted and disappear.

What you see there in that tissue section is, in fact, you see that reflector tape. So much like you're seeing at night by a car, the idea is that you can see if you illuminate tissue, you can see deeper parts of tissue because there's that reflective tape there that is out of silk. You see there it gets reintegrated in tissue.

Reintegration in the human body is not the only thing, but reintegration in the environment is important. So you have a clock; you have protein. Now a silk cup like this can be thrown away without guilt, and unlike the polystyrene cups that unfortunately fill our landfills every day, it's edible. So you can do smart packaging around food that you can cook with the food. It doesn't taste good, so I'm going to need some help with that.

But probably the most remarkable thing is that it comes full circle. Silk, during its self-assembly process, acts like a cocoon for biological matter. So if you change the recipe and you add things when you pour—so you add things to your liquid silk solution, where these things are enzymes or antibodies or vaccine—then the self-assembly process preserves the biological function of these dopants.

It makes the materials environmentally active and interactive. So that screw that you thought about beforehand can actually be used to screw a bone together, fracture bone together, and deliver drugs at the same time while your bone is healing, for example. Or you could put drugs in your wallet and not in your fridge.

So we've made a silk card with penicillin in it, and we stored penicillin at 60°C, so at 140°F, for 2 months without loss of efficacy of the penicillin. That could be potentially a good alternative to solar-powered refrigerated camels.

Of course, there's no use in storage if you can't use it. So there is this other unique material trait that these materials have, and that they're programmably degradable. What you see there is the difference in the top: you have a film that has been programmed not to degrade, and in the bottom, a film that has been programmed to degrade in water.

What you see is that the film on the bottom releases what is inside it, so it allows for the recovery of what we've stored before. This allows for controlled delivery of drugs and for reintegration in the environment.

All of these formats that you've seen—so the thread of discovery that we have really is a thread. We're impassioned with this idea that whatever you want to do, whether you want to replace a vein or a bone, or maybe be more sustainable in microelectronics, perhaps drink a coffee in a cup and throw it away without guilt, maybe carry your drugs in your pocket, deliver them inside your body, or deliver them across the desert—the answer may be in a thread of silk.

Thank you. [Music]