 I would now like to introduce our next speaker, Michelle Strickland, and she's going to be talking about spider silk hacking nature's strongest fibre. Thank you. Thank you. It's great to be here. I'm Michelle Strickland. I've been working at the University of Nottingham now for almost four years. If I were to describe my job, I'd say I look at the back end of a spider for a living, but there's a bit more to it than that. Spider silk is my subject, so hopefully you'll learn a bit and enjoy it. I will say I am around for questions afterwards. I did mostly write this talk yesterday, so it might not be as understandable as it could be, but I'm very happy to explain the stuff later, and I don't mind because that's my fault, not yours. Spiders have been around for a little while. The earliest fossil evidence we have of spiders goes back nearly 400 million years. About 12 million years after that is when we see the first evidence of silk. Now, this isn't the use of silk that we see today. Spiders have continued to evolve from that, but that's when we start to see it, and that's what we have evidence for. And I checked this morning at the present time, there are 47,688 recognised species of spider. That number goes up every week, and there have been at least 4,000 species added in the last four years. So we still don't know today just how many spiders there are in the world, and we're still learning lots about them. But I'm going to talk about silk, and spiders have worked out a myriad of different ways to utilise their silk. They're one of the few types of animals that spin silk throughout their lifetimes, and they do this to great effect. So the top two pictures you'll see spiders spin those capture spirals. So when people think of spider webs, they think of these beautiful spirals, but spiders use silk for their other things. So they'll use it to line burrows to keep them safe. They use it to wrap their egg sacs, to keep them dry, to keep them protected from the environment. But my personal favourite use of spiders and their silk is as a physical gill. So the Diving Bell Spider is the only spider that actually lives in freshwater in ponds. One of the adaptations they have is they're able to spin silk. They spin a silk and web under water. They then pull bubbles of air down from the surface, release that under the web, and they form a bubble of air under water that's held there by the silk. But the really cool thing about this is this web allows for gas diffusion. So oxygen in the surrounding water can diffuse into the air bubble, and carbon dioxide that the spider is breathing out can diffuse back out into the water. So these spiders can stay underwater for weeks at a time without having to develop gills. That's what they use their silk for. So I'm a big fan of those. They're very pretty. Spider silk is very useful to us as humans. It goes back hundreds of years, hundreds and thousands of years. The ancient Greeks used to collect spider silk and use it in wound dressings. If you apply clean silk and webs to an open wound, it can help with the healing process. More recently, individual strands of silk have been used in gun sites, in micrometres. One of the early telescopes at the Greenwich Observatory used spider silk in the micrometres so they could measure the distance and the movements between stars and planets. You can collect spider silk and spin it into a cloth as well. I think it was about ten years ago now. More recently than that. There was a beautiful exhibit where a group had collected silk from golden orbwebers spiders and they spun it into this beautiful cape and also into a kind of shawl. That's been on display and going around the world as well. On a more medical practical scale, researchers have been looking at spider silk and saying, actually, we can use silk in medicine. It's been done before. We can do it again. We can use silk to promote cellular growth. Some basic studies have shown that if you put in a line of silk where a damaged nerve can be, either with or without stem cells, you actually get nerve regeneration. That's really cool and I'd really love to see more of that. But to collect silk, it's a difficult thing. You can't just milk a spider. It's not like a silk worm where they spin it out. In order to get silk that you can use, you have to reel it from the spider. You pin the spider down and you can just pull the silk. It doesn't do them any harm and pinning down just stops them from cutting the silk. You can farm spiders, but the problem you have with farming spiders is if you put a load of spiders in a box, when you come back later, what you have is one slightly larger, very well-fed spider. They're not very good for farming. They're quite hard to keep and so it's very time-consuming and very expensive. One of the things we like to do is looking into making synthetic silk, which we can do. We can make silk faster in larger quantities and in such a way that we can do stuff with it. This has been done in plants and animals. You may or may not have heard of the spider goats, which was a project over in America. Silk genes have been put into tobacco and plants, tobacco and potatoes. The problem with this is you've got these random bits of silk floating around. Plants take time to grow. There's other stuff in goat milk besides silk. There's a lot of purification and spinning to do there. At one point you could buy synthetic silk marketed as bio-steel, although I think the bio-steel you get now is slightly different. Before we go into how to make silk, we need to learn a little bit more about what spider silk actually is. There is no one kind of spider silk. You could take any garden spider anywhere on site and that spider will be capable of making up to seven different kinds of silk. These different kinds of silk have different properties. If we think of the capture web with that spiral on there, the radial lines that lead through that web, they're the frame. They need to be strong. They need to hold that web in place so that when flies come bashing into it, it doesn't break. That web then holds the capture spiral. The capture spiral is two types of silk. It's a very stretchy, very elastic silk that is designed to absorb the impact, but that's then coated in a glue because then once you've got your prey, you want it to stay there. These silks are held together by a third kind of silk, which is a silk and cement. Your silk's just going to flop off. It needs to stick to the environment. There are other kinds of silk. Wrapping silk is also incredibly tough because you need to restrain your prey. You've got egg casing silk and there's evidence that that signs you microbial because you don't want your eggs rotting over the winter while they're waiting for spring. There's a whole range of mixtures and functions and all of those come out of one spider, but not all spiders make all kinds of silk. You take something like a tarantula, which is a very basic kind of spider. They've only got one kind of silk gland. They'll only make one or two very simple kinds of silk. The garden orbweavers we see have up to seven different glands and each of those glands is specialised to produce a particular kind of silk. But having said that, there are a lot of similarities between how these different silks are made. So a basic diagram of a spider silk gland on the left-hand side, the tiny tubule, is where silk proteins are made and these are the building blocks to become the fibre or the glue or the coating. These are then stored as a liquid inside the sack in the middle. And then when the spider needs a silk, the very long thin duct is where the magic happens. And I say magic because we still don't fully understand it although we do have a relatively good idea. So as the liquid silk travels down this duct, it undergoes dehydration. The individual parts experience mechanical stress and there is also a change in the acidic properties of the duct. And all of this contributes towards individual silk proteins folding together and forming the fibre that then comes out the end. And this is where it comes out of, the spinarets of the spider. They come in a range of shapes and sizes, but I just think they're beautiful in each of these nozzles. Each of these spinarets and spiders, they're innovated, they're muscular, they can be moved and the spider can have control over the thickness of the diameter of the silk that it produces. So if a spider is particularly hungry, it might be more inclined to make a thicker, stronger kind of silk to make sure that dinner doesn't run away. But what is silk? What is it really made of? And simplifying enormously, silk is just a collection of amino acids folded together in a specific way. And to get there you take the DNA of the spider, which is the master code. You make a copy of that code and then that code tells you which amino acid to stick on in the right place at the right time. And then you just throw that copy away and continue. And how those amino acids form, oh hello, there we go, give it the different structure and the different properties. So if those amino acids spiral and round into a spiral, you're going to get a silk that's more elastic and stretchy. If they fall together into a sheet, then that silk is going to be much stronger and much tougher. If we zoom out a bit more, if we take a silk gene, all the genes share a common layout. So if you imagine this as a bit like a book laid out in front of you, at either end of the silk you've got the start and the end of these protein building blocks. And these are important for the formation of silk fibre. This we know. The section in the middle is a repeating section. And this is what gives the silk, this is the part that gives the silk the properties. This is just a short section, it could be a shorter, a long section of instructions that's repeated over and over and over again. So silk genes are enormous. But the important thing is this structure is broadly the same irrespective of which kind of silk you're looking for, whether you have a glue or a fibre. And this is enough that we can start to make synthetic silk. So we can take four repeating regions and the finishing, the end terminal of a silk gene. We can move that into a bacteria and we can use that to produce synthetic fibres. What's interesting is if you were to include the other ends, the other terminal region, this is how the spider stops the silk from preemptively forming a fibre while it's in the storage duct. So you have the end of the gene which says, I want to make a fibre, and the end of the gene that goes, no, no, no, not yet when the time is right. But if we're going to make basic synthetic silk, all we need is just the fibre-forming part and some repeat regions to give us the silk fibres. And to get there, we need to modify some bacteria. Now, bacteria are great. Unlike plants and animals, you can easily modify bacteria without hacking the genome. So in a bacteria, you've got the nucleus going on, that's the genome in a bacteria, but they also have these circular pieces of DNA which bacteria use to transfer the information between them. So if they say, oh, we've got this antibiotic resistance gene, let's share it with all our friends, they would do it on these circular pieces of DNA. And we can hijack that, and we can use that to make silk. So we can take these circular pieces of DNA out, we can cut them open, we can paste in this section of DNA from spider silk and then stick it back in the bacteria. And the bacteria goes, great, I've got some new information, let's make that protein. And then so you can breed lots and lots of these bacteria, you can put them in big bats, you can ferment them, and then it's much easier to extract that silk, to purify it, and then do stuff with it. And the nice thing is, when you get this synthetic silk protein, it's still a liquid, so it hasn't formed a fibre yet, but with this version of silk, because we don't have that break, we can literally hold a flask of dope and you can just tilt it and mix it. And these fibres just form. And I think that's amazing, and it's such a lovely thing to watch. But the important thing is, they are uneven, they're different diameters, they're forming bundles, they're not as useful as they might be. But utilising microfluidics, we can take a very, very, very thin tube and we can spit the silk out of there into a bath which replicates the acidic environment and the dehydrating environment that is within the spider. And then you can just rean out a line of silk of consistent width and diameter. And that's really cool, that means we can make silk and then the next step is to go on and do stuff with it. It is appearing in industry. I don't want to stay too much about this because the industry is very secret about how they work. So far to my knowledge, there isn't anything on the market where you can walk into a shop and buy something made of spider silk. There have been promises. North Face, in collaboration with a company called Spybo, we are going to make a moon parker with the outside made of spider silk. But as far as I know, that didn't come to fruition. Bolt Threads are another American company. If you go on their website, you can apply to buy a silk and tie. But I've noticed that they've been mixing spider silk with wool and selling hats. So it's not pure silk, it's pretty good, it's not bad. The best thing I've seen so far, although it's debatable as to what the product actually is, Adidas and AM silk, who are the current owners of the bio silk, make these biodegradable shoes that they say is also made from a synthetic kind of spider silk. And you could buy those. They were available in Adidas stores as a limited edition, although sadly I wasn't able to get any. But what I'm really interested in is how do you modify silk? The easiest thing to do is to take something that's really exciting and just stick it onto the silk and see what happens. So a couple of studies have looked at carbon nanotubes, or carbon nanostructures. The first study on the left, they took just a bundle of spider silk, they took it straight from the spider, reeled it up, and they just kind of rubbed it with nanotubes and a little bit of water and then separated those fibres out. And while they didn't see any increase in the tensile properties, so the spider silk didn't get any stronger, they could make it electrically conductive. So you then have a relatively strong fibre straight from the spider, you can make electrically conductive, and there are things that you could do with that. So you could be looking at biocompatible electronics, or just very fine, very strong sensors. Something which I will quite happily talk to you over a beer about is this research where they fed spiders' carbon nanotubes, as they then took silk produced by these spiders, and they found that the silks were not only... these carbon nanotubes were incorporated into the silks, and also these silks had tensile properties 10 times stronger than the native silk. Myself and a few other spider biology people are very suspicious of this work for a number of reasons. It seems very odd that you could feed spider something that they would then know to digest and move into their silk glands. It's a bit like me drinking a pint of this stuff and then having graphene coated hair. There's not really an obvious way how this would happen, but if that is something that could be replicated, then that would obviously be very, very interesting and something we would look further into. Something again that cropped up which is quite interesting is you can combine spider silk with metal ions, and this again seems to produce an increase in tensile properties, but I'm not really sure where they were going with that, and that was a good 10 years ago, but it's interesting to see about. But my favourite one is we can hack the silk itself. So when we're making the silk in the bacteria, what we do is we can starve the bacteria of a particular amino acid and give it a modified one. So you can feed the bacteria a modified kind of amino acid that has almost like an extra structure on it so you can stick stuff to this amino acid. So when the bacteria produces the silk, there is no difference in the overall structure of the silk because this amino acid behaves in the normal way, but it does mean that you can then chemically attach things to the silk. So that could be fluorescent molecules, so then when you make the silk it glows in the dark. But it could be antibiotics. It could be growth hormones. It could be things that would change or advance medical technology. So you could make a kind of silk scaffold so that if somebody were having a bone repaired, you could lay that over the bone, sew it into the body, and then as the silk biodegrades, it releases whichever medication you want to give. So you have a very localised, low dose medication right where it needs to be. That's the theory. I think that's being worked on. We'll see where that goes in a few years' time. But I'm very interested in that and I'd love to see where it goes in a few years. That's all I'm going to cover for today. So thank you very much for coming and listening into me, Waffle. You can contact me on Twitter. Happy to take questions there. Happy to take questions here. Obviously I should acknowledge the people down the left-hand side for various monies and support me indulge myself for the last four years. So thank you. Questions? Lots of people. What's the earliest fossil evidence for silk? So that was 374 million years ago. I can't remember the name that was given to the spider, but they didn't have spinorexus such. These spiders had what we call ventral plates. So they had plates on the underside of the abdomen where there were kind of these sort of spigots, the nozzles were forming. And I believe the fossils kind of show bits of silk coming out of there. We don't know what those spiders did with the silk and we don't really know anything about the silk. But that is the fossil record that we have at the moment. Thank you. Hi. Is spider silk chemically different to the silk you get from silkworms? And why do you concentrate on the spider? Is it just because silkworms only produce silk at a certain stage in their life? So that's part of it, yes. So silkworms only produce silk for one stage of their life. Spiders use it throughout. Silkworms only use silk for one purpose, which is building that cocoon. So they don't have the need to use their silk to catch prey or any of the things that spiders do. On a basic chemical basis, they're made of the same stuff. So it's the same kind of amino acids, but they use a different range of amino acids and the structure of silkworm silk that you get is different. So spider silk, you kind of get the pure fibre coming out, but with silkworms you get two fibres and they're bound together with a layer of glue, a serocin coat, which I think is how the cocoons stick together. So when you buy silk and clothing, part of the process of making that is you have to dissolve the glue and separate the fibres before they can be woven. So there is a small structural difference between the two. There is definitely a difference in the amino acids between the two. And spiders do more stuff with it. Oh, actually you've kind of answered what I was about to ask. I was surprised that the silk had evolved after spiders had split off from other arthropods. So are the two silts evolved separately, the spider and the silkworms? So silk has evolved several times across the family tree. So both spiders and insects, they've evolved separately. Even within arachnids, there are some arachnids that will use silk for a short period within their lifespan. I couldn't tell you off the top of my head what they are, but silk has evolved several times across the animal kingdom. So it's not a unique thing. It just seems to be that spiders are not themselves unique. There are one or two species of insect that do use silk throughout their lifetimes. But spiders are pretty much unique in that as a massive group, they do use silk from the moment they hatch to the moment they die. OK. OK. Thanks very much, Michelle. We'll transfer to the next talk.