Spider Web 2.0

Spider silk can be stronger than steel by weight and tougher than Kevlar. Can scientists make their own? Guest: Greg Holland, professor in the Department of Chemistry and Biochemistry at San Diego State University For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠And please email us! ⁠⁠⁠⁠⁠⁠[email protected]⁠⁠⁠⁠⁠⁠We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Noam Hassenfeld?

  Support for the show comes from Ring. Halloween's coming up, which means all sorts of ghosts and ghouls might be showing up at your doorstep. But with Ring, you're protected. Ring makes it easy to keep an eye on your home, inside and out. Battery Doorbell 2K Plus features retinal 2K clarity and up to six times enhanced zoom, so you can take a closer look without losing detail. The compact indoor cam plugs in almost anywhere, so you can check in on your home and pets while you're away. And Outdoor Cam Plus lets you keep an eye on your yard and other outdoor spaces. Halloween can be a scary time at the front door and around your home.

• 0:43Noam Hassenfeld?

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• 1:05Speaker 01

  This is Unexplainable. I'm Burt Pinkerton. Today on the show, we're hearing from a chemist named Greg Holland, who started out his career doing the kind of work you might expect from a chemistry doctorate.

• 1:17Speaker 02

  I worked on, actually, lithium rechargeable batteries.

• 1:20Speaker 01

  His PhD research involved something called a nuclear magnetic resonance spectrometer, which was basically a tool that let him peer into the underlying chemical workings of battery-related things.

• 1:33Speaker 02

  But towards the tail end of my PhD, my PhD advisor said to me, there's somebody over in biology who's trying to get me to do some of this nuclear magnetic resonance on spider silk.

• 1:48Speaker 01

  Spider silk, so the fine strands that spiders spin to make webs or stay dangling from you when you're trying to shake them off, et cetera.

• 1:58Speaker 02

  And so I said, yeah, let me work on it. And I worked on it on the tail end of my-- you know, my PhD was essentially wrapped up. But I worked on this for like three to six months, like at the very end.

• 2:10Speaker 01

  Now, before this, Greg hadn't been a huge spider enthusiast.

• 2:14Speaker 02

  I was like most people, right? Like, somebody in the house is scared of a spider, you come in and you step on it.

• 2:20Speaker 01

  But during those months in the spider lab, as he was helping the researchers out, he learned about a longstanding scientific quest, the quest to make synthetic spider silk.

• 2:31Speaker 02

  And it was just, it was like, I just fell in love with the scientific problem.

• 2:36Speaker 01

  Throughout his postdoc years, he kept thinking about it. And then, when he could, he came back to it.

• 2:42Speaker 02

  And I've been on it ever since.

• 2:49Speaker 01

  So what makes the project of synthesizing spider silk so amazing that it is worth changing a career for? Well, for one thing, there is a form of spider silk called dragline that is pretty metal.

• 3:05Speaker 02

  It's stronger than high tensile steel by weight, and it's tougher than Kevlar.

• 3:10Speaker 01

  Which is already pretty impressive in and of itself. But then if you think about how we actually make something like steel--

• 3:16Speaker 02

  You know, you have to melt iron ore, which takes extreme temperatures. So you're, you know, burning coal or using massive amounts of electricity of some sort.

• 3:26Speaker 01

  Whereas spider silk is much less dramatic.

• 3:30Speaker 02

  This is biology, right? It's this tiny little organism is just using protein, water, salts. It's very low energy. They could do it on demand. They could produce a fiber in milliseconds, and that's it. So from that standpoint, it's incredibly friendly to the environment.

• 3:51Speaker 01

  And then the super-strong dragline is just one of several different forms of silk that spiders can make.

• 3:56Speaker 02

  So when you look at a web and you see all those different fibers in that web, those are not all the same fiber.

• 4:05Speaker 01

  Dragline is used to make the framework of a web.

• 4:08Speaker 02

  But if you've ever seen an orb web where there's a spiral silk in the middle, that's called flagelliform silk. So while the framework, dragline one, is very strong and tough, that elastic spiral one is extensible like rubber.

• 4:29Speaker 01

  And unsurprisingly, there are lots of ideas about what to potentially do with materials like these.

• 4:35Speaker 02

  I mean, most of our funding comes from defense. So we have grants from the Army, we have grants from the Air Force. And so they're obviously very interested in lightweight and strong.

• 4:52Speaker 01

  There are people with interest in using spider silk for very high-performance textiles and people exploring it as an alternative to plastic. Researchers are also looking into its potential in medical applications, since spider silks was called biocompatible, meaning it plays nice inside of living things.

• 5:11Speaker 02

  So a replacement for tendon, you know? You tear a tendon in your knee. So I've, you know, torn my ACL playing basketball on my knee. And so what they do is they, you know, they take a piece of your hamstring, and then they use that to fabricate the tendon. So now you don't just have to rehab your knee, you also have to rehab your hamstring. Well, if you had a material like spider silk, you could envision using that as a tendon. And it turns out that some of the spider silks have mechanical properties that are similar to tendons.

• 5:49Speaker 01

  And then there's research looking at using spider silk-related stuff for slow-release drug delivery, wound recovery. I even spoke to a researcher who's looked into how it might help with bone regeneration.

• 6:02Speaker 02

  You know, it spans everything from, you know, defense to biomedical.

• 6:09Speaker 01

  So spider silk has all this amazing potential. But you can't really ask a spider nicely to weave you a tendon. And spiders are not like silkworms, which you can keep together and farm commercially for their silk, right? They're carnivores, they might eat each other. So if people want a lot of spider silk to do cool things with, kind of need researchers like Greg to work out some kind of synthetic alternative.

• 6:38Speaker 02

  It seems like a problem that's solvable, right? Because something has done it. So here it is, it's right in front of us. We have the answer. We just need to figure it out. So it's the perfect problem.

• 6:52Speaker 01

  Spiders are almost like living, three-dimensional blueprints for Greg to follow.

• 6:58Speaker 02

  So you have the ingredients, you can hold the ingredients, you can do all the experiments you want on the ingredients, and then you can collect the silk, right? So you can hold that in your hand. And so it just seemed like this is a problem that you can really attack.

• 7:16Speaker 01

  Except, of course, it can be kind of hard to follow nature's blueprints. So after the break, we'll see what that looks like. And also, what new questions come up as researchers like Greg start to unravel spider silk's secrets.

• 7:38Noam Hassenfeld?

  Support for the show comes from Ring. This Halloween, you never know what kind of spooky characters might show up at your door. With Ring, you can keep an eye on what's happening around your home right from your phone. So whether it's trick-or-treaters, unexpected visitors, or something that goes bump in the night, Ring helps you stay in the know. With Battery Doorbell 2K Plus, you can keep an eye on deliveries at your front door, giving you extra peace of mind that your packages will be there when you get home. Outdoor Cam Plus lets you check in on your yard and outdoor spaces with clear retinal 2K video that lets you zoom in and see the finer details. For inside, the compact indoor cam plugs in almost anywhere, letting you easily check

• 8:22Noam Hassenfeld?

  in on your home and pets while you're out. So whether you're at work, out of town, or simply out running errands, Ring makes it easy to keep an eye on your home wherever you are. Halloween can be a scary time at the front door and around your home. But with Ring, you're protected. Shop cameras, doorbells, and more at ring.com.

• 8:49Speaker 03

  But the spider is endowed with the ability to perform an engineering feat that defies man's ability to fully comprehend.

• 8:57Speaker 01

  All right. If you want to spin synthetic spider silk, there are a few ways to go about it. One approach is to genetically engineer silkworms to try and spin silk that mimics spider silk's properties. So there's a recent National Geographic article that profiled a biotech company that's using this approach. And they're making something that the authors describe as not quite spider silk, but super silk. Another approach, though, is to try and figure out what's happening inside of the spider, how they do their spinning, and then imitate that. And the first step there is to make the raw ingredients for spider silk, because you can't spin wool into yarn if you don't have wool.

• 9:41Speaker 01

  So scientists have spent a fair amount of time and energy trying to make a sort of spider equivalent of wool, which is to say spider silk proteins.

• 9:50Speaker 02

  These spider silk proteins, they're very, very large. So that's what makes them challenging to produce biosynthetically.

• 10:02Speaker 01

  But synthetic biologists have used a variety of techniques to make these tricky proteins, some of which are more splashy than others. One Canadian company, for example, genetically engineered goats to express synthetic spider silk proteins in their milk at one point. But researchers also, perhaps less sensationally, have modified bacteria, bugs, plants, et cetera, to get them to make these kinds of proteins. And then, once you have the proteins, or something like them, researchers have found that you can skip the whole silk thing and turn them into stuff like gels, or films, or foams. And they've explored ways to use those kinds of forms,

• 10:45Speaker 01

  for example, some of the biomedical applications we've mentioned. But if you are determined to make a fiber, a strand of silk, you then have to put your proteins through a kind of a spinning wheel of sorts. And doing that correctly also remains something of a challenge.

• 11:06Speaker 01

  Craig told me people have tried a lot of different things to actually spin their raw ingredients into synthetic silk.

• 11:13Speaker 02

  All of these things worked from the standpoint of like, they could produce a fiber. But was the fiber as strong as spider silk? Was it as tough as spider silk? Did it have the extensibility of spider silk?

• 11:26Speaker 01

  One researcher I spoke to said a lot of progress has actually been made on this front. He pointed to a 2024 paper that seemed like a leap forward. And then there's also an earlier paper where scientists said they were able to replicate several properties of spider silk. There are companies that make materials with cool properties out of spider silk proteins. But the researcher also told me that there was still work to be done here, especially in trying to sort of make spider silk consistently and affordably. And that, quote, "The most sophisticated system is the one that belongs to the spider." So that is where Greg and his lab come in. One of his projects is to better understand the sophisticated system that belongs to the spider,

• 12:10Speaker 01

  to kind of peek under the hood at the underlying chemistry and all the steps the spiders take in the hopes that researchers can then use that information to do a better job of imitating those steps.

• 12:25Speaker 01

  So if you walk into his lab, he told me there is a wall full of spiders. He's got some of the spiders that weave the sort of classic spider webs that we know and love, these spiders known as orb weavers.

• 12:38Speaker 02

  My students, they call them the divas. They're very delicate. They need a lot of space, you know? They're seasonal. You know, they come, they show their face for a couple of months, and then they just die off, you know?

• 12:53Speaker 01

  And then he also has a bunch of black widows, which are apparently not divas. Like, yes, they're venomous, and they can cause people extreme pain, muscle cramping, body aches, severe nausea, et cetera. But if you can move past that, they are apparently great lab guests.

• 13:11Speaker 02

  You could just put them in these tiny little Dixie cup assemblies. You give them a cricket, a little water, very small confinement. You know, they like to live in cracks out on your patio. They always hide, right? And they're very robust, and they'll live in a lab for a couple of years even.

• 13:30Speaker 01

  Black widows also apparently make strong spider silk. And then their silk has been studied pretty extensively. So they've really, they've earned their spot in Greg's wall of spiders.

• 13:40Speaker 02

  But for the most part, like, outside of some spiders in captivity, the rest of my lab very much looks like a chemistry lab. I mean, we have peptide synthesizers where we can make little pieces of the protein to do our studies on. We have thermal analysis tools. We have spectrometers.

• 14:00Speaker 01

  Everything they need to look at the hidden world of spider chemistry and study their blueprints in detail.

• 14:06Speaker 02

  So at the very, very fundamental, atom by atom, what's happening?

• 14:13Speaker 01

  Greg has tried to work out what's happening at different steps in the spider's silk making. So, for example, after the long, complicated silk proteins are synthesized, the spiders actually store them for future use.

• 14:26Speaker 02

  They're stored in a sack, a glandular sack, where they contain, it's a very concentrated protein solution.

• 14:35Speaker 01

  And Greg spent several years trying to figure out what was going on in that solution in those sacks. Because you have this liquid that is just packed full of all these proteins that are really good at aggregating, or coming together and folding themselves up.

• 14:52Speaker 02

  One of the big questions was, why don't they order themselves? Like, they want to aggregate. They want to form fibers. How do they stop from doing that?

• 15:01Speaker 01

  He says they still haven't fully answered that question, but they did learn a lot about how the proteins kind of separate themselves out inside the glands in ways that seem to prevent them from clumping up until the spider is ready for them to. And then, in his more recent work, he's looked at sort of what happens next in the process. So when a spider is ready to spin a thread, these proteins and liquid leave the gland, and they travel through these complicated systems of ducts where the proteins get treated and sort of prepped for spinning.

• 15:37Speaker 02

  And so there's changes in different ions that are introduced. There's changes in pH. Water is being removed. We call it the process. It's the process.

• 15:50Speaker 01

  In December, Greg and his team published a paper about one particular part of that process. And so part of that was, they looked at one of the ions that was introduced, this thing called phosphate. And they worked to understand sort of what precisely the phosphate was doing to the proteins as they pass through the duct. And this is just sort of one small step in the much larger spinning process. Greg freely admits they have many more steps to decode, so more ions to understand, more proteins to study. But his hope is that, sort of step by step, they will get closer to understanding spiders' spinning secrets.

• 16:31Speaker 01

  So, the end, right? No. There is one more tangle in the web of this story.

• 16:39Speaker 02

  Yeah, so this is where things get a little bit more in the realm of, I'm making a bit of a jump.

• 16:49Speaker 01

  Greg is, as you hear, very careful to say that everything from here on out is speculative. But some people, he says, had a bit of a question about these long spider proteins that get tangled up into fibers. Because there is another situation where people talk a lot about tangling proteins.

• 17:12Speaker 02

  Neurodegenerative diseases, right? You get protein aggregation, which forms plaques in the brain.

• 17:20Speaker 01

  These plaques are a key feature of Alzheimer's disease. There's still a lot of debate about what exactly their role is in the disease, but they are one of the things that people look for to diagnose Alzheimer's. And these plaques form when protein fragments clump together into protein filaments.

• 17:39Speaker 02

  Those are fibrils. They're fibers.

• 17:44Speaker 01

  They're fibers with something called a beta-sheet structure, which is a technical term, but I use it because it turns out that some forms of spider silk also have a beta-sheet structure. So the proteins in the brain are making fibers. So are the proteins in spiders. The brain's fibers have a structural similarity to some of the fibers made by spiders. And then Greg says that the two also have sort of a process step in common.

• 18:13Speaker 02

  Again, I'm not an Alzheimer's expert by any stretch, but I'm just drawing the dots between that literature and what we're seeing. And all I can tell you is there's just a lot of analogies.

• 18:29Speaker 01

  And so Greg wonders if the two are similar, if what's happening in spiders looks even a little bit like what's happening in the brain. Could understanding what spider proteins do help us understand our brains, too?

• 18:46Speaker 01

  Like, what if we could, say, learn something from spiders' glands? And how they prevent proteins from forming fibers before the spider is ready for them to?

• 18:55Speaker 02

  That's a jump. That's a leap. But it's certainly intriguing, right?

• 19:03Speaker 01

  To get any answers here, he or some other spider people would probably need to go talk to some neurodegenerative disease people.

• 19:10Speaker 02

  And these are not two communities of people that talk a lot, right? Like, people studying spider silk and people studying, you know, neurodegenerative disease aren't exactly at the same conferences.

• 19:24Speaker 01

  I did actually reach out to two researchers who studied neurodegenerative diseases. And their overall takeaway was that there would need to be a lot more work done here to see if spiders had anything useful to teach us. But they wouldn't totally rule out the possibility. So I guess if a PhD student studying lithium ion batteries could spend a little time in a spider lab and emerge as a lifelong spider researcher, then maybe there is a PhD student out there somewhere who is focused on neurodegenerative diseases, and they just need to spend a couple of months in a spider lab, too, just to see what happens.

• 20:15Speaker 01

  This episode was produced by me, Byrd Pinkerton. It was edited by Meredith Hodnot. Mara runs the show, and Joanna Solotaroff is the editorial director. Matt Boynton did the mixing and the sound design. Melissa Hirsch checked the facts. Noam Hasenfeld does our music. Valerie Shankman, Jake Reynolds, and Kareem Karia are the fact that some species of spiders form colonies. Thanks always to Brian Resnick for co-creating the show with me and Noam. Thanks also to the researchers who spoke with me for this episode. Gal Betan, David Teplow, Aliyazgar Salem, Jeff Yarger, and Fiorenzo Omenato. If you, our listeners, have thoughts about spiders or other Halloweeny topics, please reach out.

• 20:59Speaker 01

  We are at [email protected]. If you'd like to support the show and the journalism that Vox does, we would love it if you would become a member. It's very easy to do. Just go to vox.com/members, and you will not only get access to all of Vox's journalism, you will also know in your heart that you are supporting all of Vox's journalism. And for those of you who have emailed us to let us know that you signed up for our membership program because of Unexplainable, thank you. It makes a really big difference. Thank you also to those of you who left us a nice review on your podcast platform of choice, or just told someone in your life about the show. You are the best. Unexplainable is part of the Vox Media Podcast Network, and we will be back very soon

• 21:43Speaker 01

  with another episode about everything that we do not know.

• 21:53Noam Hassenfeld?

  Support for the show comes from Ring. Halloween's coming up, which means all sorts of ghosts and ghouls might be showing up at your doorstep. But with Ring, you're protected. Ring makes it easy to keep an eye on your home, inside and out. Battery Doorbell 2K Plus features Retinal 2K Clarity and up to six times Enhanced Zoom, so you can take a closer look without losing detail. The compact indoor cam plugs in almost anywhere, so you can check in on your home and pets while you're away. An outdoor cam plus lets you keep an eye on your yard and other outdoor spaces. Halloween can be a scary time at the front door and around your home.

• 22:37Noam Hassenfeld?

  But with Ring, you're protected. Shop cameras, doorbells, and more at ring.com.