Tag Archives: spider silk

Making spider silk stronger by feeding graphene and carbon nanotubes to spiders

Spider silk is already considered a strong and tough material but now scientists have found a way to enhance those properties. From an August 15, 2017 Institute of Physics Publishing press release (also on EurekAlert),

…  researchers in Italy and the UK have found a way to make Spidey’s silk a lot stronger, using various different spider species and carbon nanotubes or graphene.

The research team, led by Professor Nicola Pugno at the University of Trento, Italy, succeeded in having their spiders produce silk with up to three times the strength and ten times the toughness of the regular material.

Their discovery, published today in the journal 2D Materials, could pave the way for a new class of bionicomposites, with a wide variety of uses.

Professor Pugno said: “Humans have used silkworm silks widely for thousands of years, but recently research has focussed on spider silk, as it has extremely promising mechanical properties. It is among the best spun polymer fibres in terms of tensile strength, ultimate strain, and especially toughness, even when compared to synthetic fibres such as Kevlar.

“We already know that there are biominerals present in in the protein matrices and hard tissues of insects, which gives them high strength and hardness in their jaws, mandibles and teeth, for example. So our study looked at whether spider silk’s properties could be ‘enhanced’ by artificially incorporating various different nanomaterials into the silk’s biological protein structures.”

To do this, the team exposed three different spider species to water dispersions containing carbon nanotubes or graphene.

After collecting the spiders’ silk, the team tested its tensile strength and toughness.

Professor Pugno said: “We found that the strongest silk the spiders spun had a fracture strength up to 5.4 gigapascals (GPa), and a toughness modulus up to 1,570 joules per gram (J/g). Normal spider silk, by comparison, has a fracture strength of around 1.5 GPa and a toughness modulus of around 150 J/g.

“This is the highest fibre toughness discovered to date, and a strength comparable to that of the strongest carbon fibres or limpet teeth. These are still early days, but our results are a proof of concept that paves the way to exploiting the naturally efficient spider spinning process to produce reinforced bionic silk fibres, thus further improving one of the most promising strong materials.

“These silks’ high toughness and resistance to ultimate strain could have applications such as parachutes.”

“Furthermore, this process of the natural integration of reinforcements in biological structural materials could also be applied to other animals and plants, leading to a new class of “bionicomposites” for innovative applications.”

Remember this? “You are what you eat.” If you’ve ever had doubts about that saying, these spiders should be laying them to rest.

Sadly, this news release doesn’t explain much about the decision to feed the spiders graphene or carbon nanotubes, which are identical other than in their respective shapes (sheet vs tube)  and whether those shapes did or did not affect the strength of the silk.

Here’s a link to and a citation for the paper,

Spider silk reinforced by graphene or carbon nanotubes by Emiliano Lepore, Federico Bosia, Francesco Bonaccorso, Matteo Bruna, Simone Taioli, Giovanni Garberoglio, Andrea C Ferrari, and Nicola Maria Pugno. 2D Materials, Volume 4, Number 3 DOI: https://doi.org/10.1088/2053-1583/aa7cd3 Published 14 August 2017

© 2017 IOP Publishing Ltd

This paper is behind a paywall.

Pugno was most recently mentioned here in a May 29, 2015 posting where he was listed as an author for a paper on synthesizing spider silk. Prior to 2015 I was familiar with Pugno’s name due to his work on adhesiveness in geckos.

Antibiotic synthetic spider silk

I have a couple of questions, what is ‘click’ chemistry and how does a chance meeting lead to a five-year, interdisciplinary research project on synthetic spider silk? From a Jan. 4, 2017 news item on ScienceDaily,

A chance meeting between a spider expert and a chemist has led to the development of antibiotic synthetic spider silk.

After five years’ work an interdisciplinary team of scientists at The University of Nottingham has developed a technique to produce chemically functionalised spider silk that can be tailored to applications used in drug delivery, regenerative medicine and wound healing.

The Nottingham research team has shown for the first time how ‘click-chemistry’ can be used to attach molecules, such as antibiotics or fluorescent dyes, to artificially produced spider silk synthesised by E.coli bacteria. The research, funded by the Biotechnology and Biological Sciences Research Council (BBSRC) is published today in the online journal Advanced Materials.

A Jan. 3, 2016 University of Nottingham press release (also on EurekAlert), which originated the news item, provides a few more details about ‘click’ chemistry (not enough for me) and more information about the research,

The chosen molecules can be ‘clicked’ into place in soluble silk protein before it has been turned into fibres, or after the fibres have been formed. This means that the process can be easily controlled and more than one type of molecule can be used to ‘decorate’ individual silk strands.

Nottingham breakthrough

In a laboratory in the Centre of Biomolecular Sciences, Professor Neil Thomas from the School of Chemistry in collaboration with Dr Sara Goodacre from the School of Life Sciences, has led a team of BBSRC DTP-funded PhD students starting with David Harvey who was then joined by Victor Tudorica, Leah Ashley and Tom Coekin. They have developed and diversified this new approach to functionalising ‘recombinant’ — artificial — spider silk with a wide range of small molecules.

They have shown that when these ‘silk’ fibres are ‘decorated’ with the antibiotic levofloxacin it is slowly released from the silk, retaining its anti-bacterial activity for at least five days.

Neil Thomas, a Professor of Medicinal and Biological Chemistry, said: “Our technique allows the rapid generation of biocompatible, mono or multi-functionalised silk structures for use in a wide range of applications. These will be particularly useful in the fields of tissue engineering and biomedicine.”

Remarkable qualities of spider silk

Spider silk is strong, biocompatible and biodegradable. It is a protein-based material that does not appear to cause a strong immune, allergic or inflammatory reaction. With the recent development of recombinant spider silk, the race has been on to find ways of harnessing its remarkable qualities.

The Nottingham research team has shown that their technique can be used to create a biodegradable mesh which can do two jobs at once. It can replace the extra cellular matrix that our own cells generate, to accelerate growth of the new tissue. It can also be used for the slow release of antibiotics.

Professor Thomas said: “There is the possibility of using the silk in advanced dressings for the treatment of slow-healing wounds such as diabetic ulcers. Using our technique infection could be prevented over weeks or months by the controlled release of antibiotics. At the same time tissue regeneration is accelerated by silk fibres functioning as a temporary scaffold before being biodegraded.”

The medicinal properties of spider silk recognised for centuries.

The medicinal properties of spider silk have been recognised for centuries but not clearly understood. The Greeks and Romans treated wounded soldiers with spider webs to stop bleeding. It is said that soldiers would use a combination of honey and vinegar to clean deep wounds and then cover the whole thing with balled-up spider webs.

There is even a mention in Shakespeare’s Midsummer Night’s Dream: “I shall desire you of more acquaintance, good master cobweb,” the character ‘Bottom’ said. “If I cut my finger, I shall make bold of you.”

The press release goes on to describe the genesis of the project and how this multidisciplinary team was formed in more detail,

The idea came together at a discipline bridging university ‘sandpit’ meeting five years ago. Dr Goodacre says her chance meeting at that event with Professor Thomas proved to be one of the most productive afternoons of her career.

Dr Goodacre, who heads up the SpiderLab in the School of Life Sciences, said: “I got up at that meeting and showed the audience a picture of some spider silk. I said ‘I want to understand how this silk works, and then make some.’

“At the end of the session Neil came up to me and said ‘I think my group could make that.’ He also suggested that there might be more interesting ‘tweaks’ one could make so that the silk could be ‘decorated’ with different, useful, compounds either permanently or which could be released over time due to a change in the acidity of the environment.”

The approach required the production of the silk proteins in a bacterium where an amino acid not normally found in proteins was included. This amino acid contained an azide group which is widely used in ‘click’ reactions that only occur at that position in the protein. It was an approach that no-one had used before with spider silk — but the big question was — would it work?

Dr Goodacre said: “It was the start of a fascinating adventure that saw a postdoc undertake a very preliminary study to construct the synthetic silks. He was a former SpiderLab PhD student who had previously worked with our tarantulas. Thanks to his ground work we showed we could produce the silk proteins in bacteria. We were then joined by David Harvey, a new PhD student, who not only made the silk fibres, incorporating the unusual amino acid, but also decorated it and demonstrated its antibiotic activity. He has since extended those first ideas far beyond what we had thought might be possible.”

David Harvey’s work is described in this paper but Professor Thomas and Dr Goodacre say this is just the start. There are other joint SpiderLab/Thomas lab students working on uses for this technology in the hope of developing it further.

David Harvey, the lead author on this their first paper, has just been awarded his PhD and is now a postdoctoral researcher on a BBSRC follow-on grant so is still at the heart of the research. His current work is focused on driving the functionalised spider silk technology towards commercial application in wound healing and tissue regeneration.

Here’s a link to and a citation for the paper,

Antibiotic Spider Silk: Site-Specific Functionalization of Recombinant Spider Silk Using “Click” Chemistry by David Harvey, Philip Bardelang, Sara L. Goodacre, Alan Cockayne, and Neil R. Thomas. Advanced Materials DOI: 10.1002/adma.201604245 Version of Record online: 28 DEC 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

I imagine Mr. Cockayne’s name has led to much teasing over the years. People who have names with that kind of potential tend to either change them or double down and refuse to compromise.

Spider silk as a bio super-lens

Bangor University (Wales, UK) is making quite the impact these days. I’d never heard of the institution until their breakthrough with nanobeads (Sept. 7, 2016 posting) to break through a resolution barrier and now there’s a second breakthrough with their partners at Oxford University (England, UK). From an Aug. 19, 2016 news item on ScienceDaily (Note: A link has been removed),

Scientists at the UK’s Bangor and Oxford universities have achieved a world first: using spider-silk as a superlens to increase the microscope’s potential.

Extending the limit of classical microscope’s resolution has been the ‘El Dorado’ or ‘Holy Grail’ of microscopy for over a century. Physical laws of light make it impossible to view objects smaller than 200 nm — the smallest size of bacteria, using a normal microscope alone. However, superlenses which enable us to see beyond the current magnification have been the goal since the turn of the millennium.

Hot on the heels of a paper (Sci. Adv. 2 e1600901,2016) revealing that a team at Bangor University’s School of Electronic Engineering has used a nanobead-derived superlens to break the perceived resolution barrier, the same team has achieved another world first.

Now the team, led by Dr Zengbo Wang and in colloboration with Prof. Fritz Vollrath’s silk group at Oxford University’s Department of Zoology, has used a naturally occurring material — dragline silk of the golden web spider, as an additional superlens, applied to the surface of the material to be viewed, to provide an additional 2-3 times magnification.

This is the first time that a naturally occurring biological material has been used as a superlens.

An Aug. 19, 2016 Bangor University press release (also on EurekAlert), which originated the news item, provides more information about the new work,

In the paper in Nano Letters (DOI: 10.1021/acs.nanolett.6b02641, Aug 17 2016), the joint team reveals how they used a cylindrical piece of spider silk from the thumb sized Nephila spider as a lens.

Dr Zengbo Wang said:

“We have proved that the resolution barrier of microscope can be broken using a superlens, but production of manufactured superlenses invovles some complex engineering processes which are not widely accessible to other reserchers. This is why we have been interested in looking for naturally occurring superlenses provided by ‘Mother Nature’, which may exist around us, so that everyone can access superlenses.”

Prof Fritz Vollrath adds:

“It is very exciting to find yet another cutting edge and totally novel use for a spider silk, which we have been studying for over two decades in my laboratory.”

These lenses could be used for seeing and viewing previously ‘invisible’ structures, including engineered nano-structures and biological micro-structures as well as, potentially, native germs and viruses.

The natural cylindrical structure at a micron- and submicron-scale make silks ideal candidates, in this case, the individual filaments had diameters of one tenth of a thin human hair.

The spider filament enabled the group to view details on a micro-chip and a blue- ray disk which would be invisible using the unmodified optical microscope.

In much the same was as when you look through a cylindrical glass or bottle, the clearest image only runs along the narrow strip directly opposite your line of vision, or resting on the surface being viewed, the single filament provides a one dimensional viewing image along its length.

Wang explains:

“The cylindrical silk lens has advantages in the larger field-of-view when compared to a microsphere superlens. Importantly for potential commercial applications, a spider silk nanoscope would be robust and economical, which in turn could provide excellent manufacturing platforms for a wide range of applications.”

James Monks, a co-author on the paper comments: “it has been an exciting time to be able to develop this project as part of my honours degree in electronic engineering at Bangor University and I am now very much looking forward to joining Dr Wang’s team as a PhD student in nano-photonics.”

The researchers have provided a close up image with details,

Caption: (a) Nephila edulis spider in its web. (b) Schematic drawing of reflection mode silk biosuperlens imaging. The spider silk was placed directly on top of the sample surface by using a soft tape, which magnify underlying nano objects 2-3 times (c) SEM image of Blu-ray disk with 200/100 nm groove and lines (d) Clear magnified image (2.1x) of Blu-ray disk under spider silk superlens. Credit: Bangor University/ University of Oxford

Caption: (a) Nephila edulis spider in its web. (b) Schematic drawing of reflection mode silk biosuperlens imaging. The spider silk was placed directly on top of the sample surface by using a soft tape, which magnify underlying nano objects 2-3 times (c) SEM image of Blu-ray disk with 200/100 nm groove and lines (d) Clear magnified image (2.1x) of Blu-ray disk under spider silk superlens. Credit: Bangor University/ University of Oxford

Here’s a link to and a citation for the ‘spider silk’ superlens paper,

Spider Silk: Mother Nature’s Bio-Superlens by James N. Monks, Bing Yan, Nicholas Hawkins, Fritz Vollrath, and Zengbo Wang. Nano Lett., Article ASAP DOI: 10.1021/acs.nanolett.6b02641 Publication Date (Web): August 17, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Congratulations to Markus Buehler on his Foresight Institute Feynman Prize for advances in nanotechnology

A May 24, 2016 Massachusetts Institute of Technology (MIT) news release celebrates Markus Buehler’s latest award,

On May 21 [2016], Department of Civil and Environmental Engineering head and McAfee Professor of Engineering Markus J. Buehler received the 2015 Foresight Institute Feynman Prize in Theoretical Molecular Nanotechnology. Buehler’s award was one of three prizes presented by the Foresight Institute, a leading think tank and public interest organization, at its annual conference in Palo Alto, California. …

The Foresight Institute recognized Buehler for his important contributions to making nanotechnology scalable for large-scale materials applications, enabled by bottom-up multiscale computational methods, and linking new manufacturing and characterization methods.

Focusing on mechanical properties — especially deformation and failure — and translation from biological materials and structures to bio-inspired synthetic materials, his work has led to the development and application of new modeling, design, and manufacturing approaches for advanced materials that offer greater resilience and a wide range of controllable properties from the nano- to the macroscale.

Buehler’s signature achievement, according to the Institute, is the application of molecular and chemical principles in the analysis of mechanical systems, with the aim to design devices and materials that provide a defined set of functions.

“It’s an incredible honor to receive such an esteemed award. I owe this to the outstanding students and postdocs whom I had a pleasure to work with over the years, my colleagues, as well my own mentors,” Buehler said. “Richard Feynman was a revolutionary scientist of his generation. It’s a privilege to share his goals of researching molecular technology at very small scale to create new, more efficient, and better lasting materials at much larger scale that will help transform lives and industries.”

The two other award winners are Professor Michelle Y. Simmons of the University of New South Wales [Australia], who won the Feynman Prize for Experimental Molecular Nanotechnology, and Northwestern University graduate student Chuyang Cheng, who won the Distinguished Student Award.

I have featured Buehler’s work here a number of times. The most recent appearance was in  a May 29, 2015 posting about synthesizing spider’s silk.

Spider webs inspire liquid wire

Courtesy University of Oxford

Courtesy University of Oxford

Usually, when science talk runs to spider webs the focus is on strength but this research from the UK and France is all about resilience. From a May 16, 2016 news item on phys.org,

Why doesn’t a spider’s web sag in the wind or catapult flies back out like a trampoline? The answer, according to new research by an international team of scientists, lies in the physics behind a ‘hybrid’ material produced by spiders for their webs.

Pulling on a sticky thread in a garden spider’s orb web and letting it snap back reveals that the thread never sags but always stays taut—even when stretched to many times its original length. This is because any loose thread is immediately spooled inside the tiny droplets of watery glue that coat and surround the core gossamer fibres of the web’s capture spiral.

This phenomenon is described in the journal PNAS by scientists from the University of Oxford, UK and the Université Pierre et Marie Curie, Paris, France.

The researchers studied the details of this ‘liquid wire’ technique in spiders’ webs and used it to create composite fibres in the laboratory which, just like the spider’s capture silk, extend like a solid and compress like a liquid. These novel insights may lead to new bio-inspired technology.

A May 16, 2016 University of Oxford press release (also on EurekAlert), which originated the news item, provides more detail,

Professor Fritz Vollrath of the Oxford Silk Group in the Department of Zoology at Oxford University said: ‘The thousands of tiny droplets of glue that cover the capture spiral of the spider’s orb web do much more than make the silk sticky and catch the fly. Surprisingly, each drop packs enough punch in its watery skins to reel in loose bits of thread. And this winching behaviour is used to excellent effect to keep the threads tight at all times, as we can all observe and test in the webs in our gardens.’

The novel properties observed and analysed by the scientists rely on a subtle balance between fibre elasticity and droplet surface tension. Importantly, the team was also able to recreate this technique in the laboratory using oil droplets on a plastic filament. And this artificial system behaved just like the spider’s natural winch silk, with spools of filament reeling and unreeling inside the oil droplets as the thread extended and contracted.

Dr Hervé Elettro, the first author and a doctoral researcher at Institut Jean Le Rond D’Alembert, Université Pierre et Marie Curie, Paris, said: ‘Spider silk has been known to be an extraordinary material for around 40 years, but it continues to amaze us. While the web is simply a high-tech trap from the spider’s point of view, its properties have a huge amount to offer the worlds of materials, engineering and medicine.

‘Our bio-inspired hybrid threads could be manufactured from virtually any components. These new insights could lead to a wide range of applications, such as microfabrication of complex structures, reversible micro-motors, or self-tensioned stretchable systems.’

Here’s a link to and a citation for the paper,

In-drop capillary spooling of spider capture thread inspires hybrid fibers with mixed solid–liquid mechanical properties by Hervé Elettro, Sébastien Neukirch, Fritz Vollrath, and Arnaud Antkowiak. PNAS doi: 10.1073/pnas.1602451113

This paper appears to be open access.

Synthesized spider silk from Montréal, Canada

On the heels of my May 29, 2015 post about synthesized spider silk at the Massachusetts Institute of Technology (MIT), researchers at the École Polytechnique de Montréal (Polytechnique Montreal) have also synthesized spider silk according to a June 3, 2015 news item on Nanowerk (Note: A link has been removed),

Professors Frederick Gosselin and Daniel Therriault, along with their master’s student Renaud Passieux, are not related to Spiderman. Nevertheless, these Polytechnique Montreal researchers have produced an ultra-tough polymer fibre directly inspired by spider silk! They recently published an article about the project in the journal Advanced Materials (“Instability-Assisted Direct Writing of Microstructured Fibers Featuring Sacrificial Bonds”).

A June 3, 2015 École Polytechnique de Montréal news release (also on EurekAlert), which originated the news item, further describes the achievement (at the microscale rather than the nanoscale),

Three to eight microns in diameter but five to ten times tougher than steel or Kevlar: despite its lightness, spider silk has such remarkable elongation and stretch-resistance properties that humans have long sought to replicate it, in order to make products with those same characteristics.

In large part, spider silk owes its exceptional strength – meaning its ability to absorb a large amount of energy before failing – to the particular molecular structure of the protein chain of which it’s composed. The mechanical origin of its strength drew the interest of researchers at the Laboratory for Multiscale Mechanics in Polytechnique Montréal’s Department of Mechanical Engineering.

“The silk protein coils upon itself like a spring. Each loop of the spring is attached to its neighbours with sacrificial bonds, chemical connections that break before the main molecular structural chain tears,” explained Professor Gosselin, who, along with his colleague Daniel Therriault, is co-supervising Renaud Passieux’s master’s research work. He added: “To break the protein by stretching it, you need to uncoil the spring and break each of the sacrificial bonds one by one, which takes a lot of energy. This is the mechanism we’re seeking to reproduce in laboratory,”

Imitating nature with polymer fibres

Their project involves making micrometric-sized microstructured fibres that have mechanical properties similar to those of spider silk. “It consists in pouring a filament of viscous polymeric solution toward a sub-layer that moves at a certain speed. So we create an instability,” said Renaud Passieux. “The filament forms a series of loops or coils, kind of like when you pour a thread of honey onto a piece of toast. [emphasis mine] Depending on the instability determined by the way the fluid runs, the fibre presents a particular geometry. It forms regular periodic patterns, which we call instability patterns.”

The fibre then solidifies as the solvent evaporates. Some instability patterns feature the formation of sacrificial bonds when the filament makes a loop and bonds to itself. At that point, it takes a pull with a strong energy output on the resulting fibre to succeed in breaking the sacrificial bonds, as they behave like protein-based spider silk.

“This project aims to understand how the instability used in making the substance influences the loops’ geometry and, as a result, the mechanical properties of the fibres we obtain,” explained Professor Therriault. “Our challenge is that the manufacturing process is multiphysical. It draws on concepts from numerous fields: fluid mechanics, microfabrication, strength of materials, polymer rheology and more.”

A vast range of applications for future tough fibre composites

These researchers think that one day, there will certainly be composites obtained by weaving together tough fibres of the type they’re currently developing. Such composites could, for example, make it possible to manufacture new safer and lighter casings for aircraft engines, which would prevent debris from dispersing in case of explosion. Many other applications can be foreseen, from surgical devices to bulletproof clothing to vehicle parts.

Here’s a link to and a citation for the paper,

Instability-Assisted Direct Writing of Microstructured Fibers Featuring Sacrificial Bonds by Renaud Passieux, Leigh Guthrie, Somayeh Hosseini Rad, Martin Lévesque, Daniel Therriault, & Frédérick P. Gosselin. Advanced Materials  DOI: 10.1002/adma.201500603 First published: 15 May 2015

This paper is behind a paywall.

The researchers have also produced a video illustrating the ‘honey’ analogy as it relates to their work with spider silk,

Instability-Assisted Direct Writing of Micro-Structured Fibers featuring Sacrificial Bonds from Frederick P. Gosselin on Vimeo.

Synthesizing spider silk

Most of the research on spider silk and spider webs that’s featured here is usually from the Massachusetts Institute of Technology (MIT) and, more specifically, from professor Markus J. Buehler. This May 28, 2015 news item on ScienceDaily, which heralds the development of synthetic spider silk, is no exception,

After years of research decoding the complex structure and production of spider silk, researchers have now succeeded in producing samples of this exceptionally strong and resilient material in the laboratory. The new development could lead to a variety of biomedical materials — from sutures to scaffolding for organ replacements — made from synthesized silk with properties specifically tuned for their intended uses.

The findings are published this week in the journal Nature Communications by MIT professor of civil and environmental engineering (CEE) Markus Buehler, postdocs Shangchao Lin and Seunghwa Ryu, and others at MIT, Tufts University, Boston University, and in Germany, Italy, and the U.K.

The research, which involved a combination of simulations and experiments, paves the way for “creating new fibers with improved characteristics” beyond those of natural silk, says Buehler, who is also the department head in CEE. The work, he says, should make it possible to design fibers with specific characteristics of strength, elasticity, and toughness.

The new synthetic fibers’ proteins — the basic building blocks of the material — were created by genetically modifying bacteria to make the proteins normally produced by spiders. These proteins were then extruded through microfluidic channels designed to mimic the effect of an organ, called a spinneret, that spiders use to produce natural silk fibers.

A May 28, 2015 MIT news release (also on EurekAlert), which originated the news item, describes the work in more detail,

While spider silk has long been recognized as among the strongest known materials, spiders cannot practically be bred to produce harvestable fibers — so this new approach to producing a synthetic, yet spider-like, silk could make such strong and flexible fibers available for biomedical applications. By their nature, spider silks are fully biocompatible and can be used in the body without risk of adverse reactions; they are ultimately simply absorbed by the body.

The researchers’ “spinning” process, in which the constituent proteins dissolved in water are extruded through a tiny opening at a controlled rate, causes the molecules to line up in a way that produces strong fibers. The molecules themselves are a mixture of hydrophobic and hydrophilic compounds, blended so as to naturally align to form fibers much stronger than their constituent parts. “When you spin it, you create very strong bonds in one direction,” Buehler says.

The team found that getting the blend of proteins right was crucial. “We found out that when there was a high proportion of hydrophobic proteins, it would not spin any fibers, it would just make an ugly mass,” says Ryu, who worked on the project as a postdoc at MIT and is now an assistant professor at the Korea Advanced Institute of Science and Technology. “We had to find the right mix” in order to produce strong fibers, he says.

The researchers made use of computational modelling to speed up the process of synthesizing proteins for synthetic spider silk, from the news release,

This project represents the first use of simulations to understand silk production at the molecular level. “Simulation is critical,” Buehler explains: Actually synthesizing a protein can take several months; if that protein doesn’t turn out to have exactly the right properties, the process would have to start all over.

Using simulations makes it possible to “scan through a large range of proteins until we see changes in the fiber stiffness,” and then home in on those compounds, says Lin, who worked on the project as a postdoc at MIT and is now an assistant professor at Florida State University.

Controlling the properties directly could ultimately make it possible to create fibers that are even stronger than natural ones, because engineers can choose characteristics for a particular use. For example, while spiders may need elasticity so their webs can capture insects without breaking, those designing fibers for use as surgical sutures would need more strength and less stretchiness. “Silk doesn’t give us that choice,” Buehler says.

The processing of the material can be done at room temperature using water-based solutions, so scaling up manufacturing should be relatively easy, team members say. So far, the fibers they have made in the lab are not as strong as natural spider silk, but now that the basic process has been established, it should be possible to fine-tune the materials and improve its strength, they say.

“Our goal is to improve the strength, elasticity, and toughness of artificially spun fibers by borrowing bright ideas from nature,” Lin says. This study could inspire the development of new synthetic fibers — or any materials requiring enhanced properties, such as in electrical and thermal transport, in a certain direction.

Here’s a link to and a citation for the paper,

Predictive modelling-based design and experiments for synthesis and spinning of bioinspired silk fibres by Shangchao Lin, Seunghwa Ryu, Olena Tokareva, Greta Gronau, Matthew M. Jacobsen, Wenwen Huang, Daniel J. Rizzo, David Li, Cristian Staii, Nicola M. Pugno, Joyce Y. Wong, David L. Kaplan, & Markus J. Buehler. Nature Communications 6, Article number: 6892 doi:10.1038/ncomms7892 Published 28 May 2015

This paper is behind a paywall.

My two most recent (before this one) postings about Buehler’s work are an August 5, 2014 piece about structural failures and a June 4, 2014 piece about spiderwebs and music.

Finally, I recognized one of the authors, Nicola Pugno from Italy. He’s been mentioned here more than once in regard to his biomimicry work which has often been focused on geckos and their adhesive qualities as per this April 3, 2014 post announcing his book ‘An Experimental Study on Adhesive or Anti-Adhesive, Bio-Inspired Experimental Nanomaterials‘ (co-authored with Emiliano Lepore).

Studying the “feather-legged lace weaver’s” (Uloborus plumipes) web weaving abilities

It’s more commonly known in Britain as a ‘garden centre spider’ but I like ‘feather-legged lace weaver’ better. Before getting to the story, here’s an image of the spider in question,

The "garden center spider" (Uloborus plumipes) combs and pulls its silk and builds up an electrostatic charge to create sticky filaments just a few nanometers thick. It could inspire a new way to make super long and strong nanofibers. Credit: Hartmut Kronenberger & Katrin Kronenberger (Oxford University)

The “garden center spider” (Uloborus plumipes) combs and pulls its silk and builds up an electrostatic charge to create sticky filaments just a few nanometers thick. It could inspire a new way to make super long and strong nanofibers.
Credit: Hartmut Kronenberger & Katrin Kronenberger (Oxford University)

A Jan. 27, 2015 Oxford University press release (also on EurekAlert and in a Jan. 29, 2015 news item on Azonano) describes the research,

A spider commonly found in garden centres in Britain is giving fresh insights into how to spin incredibly long and strong fibres just a few nanometres thick.

The majority of spiders spin silk threads several micrometres thick but unusually the ‘garden centre spider’ or ‘feather-legged lace weaver’ [1] Uloborus plumipes can spin nano-scale filaments. Now an Oxford University team think they are closer to understanding how this is done. Their findings could lead to technologies that would enable the commercial spinning of nano-scale filaments.

The research was carried out by Katrin Kronenberger and Fritz Vollrath of Oxford University’s Department of Zoology and is reported in the journal Biology Letters.

Instead of using sticky blobs of glue on their threads to capture prey Uloborus uses a more ancient technique – dry capture threads made of thousands of nano-scale filaments that it is thought to electrically charge to create these fluffed-up catching ropes.

To discover the secrets of its nano-fibres the Oxford researchers collected adult female Uloborus lace weavers from garden centres in Hampshire, UK. They then took photographs and videos of the spiders’ spinning action and used three different microscopy techniques to examine the spiders’ silk-generating organs. Of particular interest was the cribellum, an ancient spinning organ not found in many spiders and consisting of one or two plates densely covered in tiny silk outlet nozzles (spigots).

Uloborus has unique cribellar glands, amongst the smallest silk glands of any spider, and it’s these that yield the ultra-fine ‘catching wool’ of its prey capture thread,’ said Dr Katrin Kronenberger of Oxford University’s Department of Zoology, the report’s first author. ‘The raw material, silk dope, is funnelled through exceptionally narrow and long ducts into tiny spinning nozzles or spigots. Importantly, the silk seems to form only just before it emerges at the uniquely-shaped spigots of this spider.’

False colour SEM image of a small part of the cribellum spinning plate with its unique silk outlets Image: Katrin Kronenberger (Oxford University) & David Johnston (University of Southampton)

False colour SEM image of a small part of the cribellum spinning plate with its unique silk outlets
Image: Katrin Kronenberger (Oxford University) & David Johnston (University of Southampton)

The cribellum of Uloborus is covered with thousands of tiny silk-producing units combining ducts that average 500 nanometres in length and spigots that narrow to a diameter of around 50 nanometres.

‘The swathe of gossamer, made of thousands of filaments, emerging from these spigots is actively combed out by the spider onto the capture thread’s core fibres using specialist hairs on its hind legs,’ said Professor Fritz Vollrath, the other author of the work. ‘This combing and hackling – violently pulling the thread – charges the fibres and the electrostatic interaction of this combination spinning process leads to regularly spaced, wool-like ‘puffs’ covering the capture threads. The extreme thinness of each filament, in addition to the charges applied during spinning, provides Van der Waals adhesion. And this makes these puffs immensely sticky.’

The cribellate capture thread of Uloborus plumipes, with its characteristic 'puffs', imaged with a Scanning Electron Microscope (SEM) Image: Fritz Vollrath (Oxford University)

The cribellate capture thread of Uloborus plumipes, with its characteristic ‘puffs’, imaged with a Scanning Electron Microscope (SEM)
Image: Fritz Vollrath (Oxford University)

Conventionally, synthetic polymers fibres are produced by hot-melt extrusion: these typically have diameters of 10 micrometres or above. But because thread diameter is integral to filament strength, technology that could enable the commercial production of nano-scale filaments would make it possible to manufacture stronger and longer fibres.

‘Studying this spider is giving us valuable insights into how it creates nano-scale filaments,’ said Professor Vollrath. ‘If we could reproduce its neat trick of electro-spinning nano-fibres we could pave the way for a highly versatile and efficient new kind of polymer processing technology.’

Here’s a link to and citation for the paper,

Spiders spinning electrically charged nano-fibres by Katrin Kronenberger and Fritz Vollrath. January 2015 Volume: 11 Issue: 1 DOI: 10.1098/rsbl.2014.0813 Published 28 January 2015

This is an open access paper. Note: Sometimes journals close access after a certain number of days so the paper may not be freely available after a certain time period.

Music on the web, a spider’s web, that is

I was expecting to see Markus Buehler and MIT (Massachusetts Institute of Technology) mentioned in this latest work on spiderwebs and music. Surprise! This latest research is from three universities in the UK as per a June 3, 2014 news item on ScienceDaily,

Spider silk transmits vibrations across a wide range of frequencies so that, when plucked like a guitar string, its sound carries information about prey, mates, and even the structural integrity of a web.

The discovery was made by researchers from the Universities of Oxford, Strathclyde, and Sheffield who fired bullets and lasers at spider silk to study how it vibrates. They found that, uniquely, when compared to other materials, spider silk can be tuned to a wide range of harmonics. The findings, to be reported in the journal Advanced Materials, not only reveal more about spiders but could also inspire a wide range of new technologies, such as tiny light-weight sensors.

A June 3, 2014 University of Oxford news release (also on EurekAlert), which originated the news item, explains the research and describes how it was conducted (firing bullets?),

‘Most spiders have poor eyesight and rely almost exclusively on the vibration of the silk in their web for sensory information,’ said Beth Mortimer of the Oxford Silk Group at Oxford University, who led the research. ‘The sound of silk can tell them what type of meal is entangled in their net and about the intentions and quality of a prospective mate. By plucking the silk like a guitar string and listening to the ‘echoes’ the spider can also assess the condition of its web.’

‘Most spiders have poor eyesight and rely almost exclusively on the vibration of the silk in their web for sensory information,’ said Beth Mortimer of the Oxford Silk Group at Oxford University, who led the research. ‘The sound of silk can tell them what type of meal is entangled in their net and about the intentions and quality of a prospective mate. By plucking the silk like a guitar string and listening to the ‘echoes’ the spider can also assess the condition of its web.’

This quality is used by the spider in its web by ‘tuning’ the silk: controlling and adjusting both the inherent properties of the silk, and the tensions and interconnectivities of the silk threads that make up the web. To study the sonic properties of the spider’s gossamer threads the researchers used ultra-high-speed cameras to film the threads as they responded to the impact of bullets. [emphasis mine] In addition, lasers were used to make detailed measurements of even the smallest vibration.

‘The fact that spiders can receive these nanometre vibrations with organs on each of their legs, called slit sensillae, really exemplifies the impact of our research about silk properties found in our study,’ said Dr Shira Gordon of the University of Strathclyde, an author involved in this research.

‘These findings further demonstrate the outstanding properties of many spider silks that are able to combine exceptional toughness with the ability to transfer delicate information,’ said Professor Fritz Vollrath of the Oxford Silk Group at Oxford University, an author of the paper. ‘These are traits that would be very useful in light-weight engineering and might lead to novel, built-in ‘intelligent’ sensors and actuators.’

Dr Chris Holland of the University of Sheffield, an author of the paper, said: ‘Spider silks are well known for their impressive mechanical properties, but the vibrational properties have been relatively overlooked and now we find that they are also an awesome communication tool. Yet again spiders continue to impress us in more ways than we can imagine.’

Beth Mortimer said: ‘It may even be that spiders set out to make a web that ‘sounds right’ as its sonic properties are intimately related to factors such as strength and flexibility.’

The research paper has not yet been published in Advanced Materials (I checked this morning, June 4, 2014).

However, there is this video from the researchers,

As for Markus Buehler’s work at MIT, you can find out more in my Nov. 28, 2012 posting, Producing stronger silk musically.

Producing stronger silk musically

Markus Buehler and his interdisciplinary team (my previous posts on their work includes Gossamer silk that withstands hurricane force winds and Music, math, and spiderwebs) have synthesized a new material based on spider silk. From the Nov. 28, 2012 news item on ScienceDaily,

Pound for pound, spider silk is one of the strongest materials known: Research by MIT’s [Massachusetts Institute of Technology] Markus Buehler has helped explain that this strength arises from silk’s unusual hierarchical arrangement of protein building blocks.

Now Buehler — together with David Kaplan of Tufts University and Joyce Wong of Boston University — has synthesized new variants on silk’s natural structure, and found a method for making further improvements in the synthetic material.

And an ear for music, it turns out, might be a key to making those structural improvements.

Here’s Buehler describing the work in an MIT video clip,

The Nov. 28, 2012 MIT news release by David Chandler provides more details,

Buehler’s previous research has determined that fibers with a particular structure — highly ordered, layered protein structures alternating with densely packed, tangled clumps of proteins (ABABAB) — help to give silk its exceptional properties. For this initial attempt at synthesizing a new material, the team chose to look instead at patterns in which one of the structures occurred in triplets (AAAB and BBBA).

Making such structures is no simple task. Kaplan, a chemical and biomedical engineer, modified silk-producing genes to produce these new sequences of proteins. Then Wong, a bioengineer and materials scientist, created a microfluidic device that mimicked the spider’s silk-spinning organ, which is called a spinneret.

Even after the detailed computer modeling that went into it, the outcome came as a bit of a surprise, Buehler says. One of the new materials produced very strong protein molecules — but these did not stick together as a thread. The other produced weaker protein molecules that adhered well and formed a good thread. “This taught us that it’s not sufficient to consider the properties of the protein molecules alone,” he says. “Rather, [one must] think about how they can combine to form a well-connected network at a larger scale.”

The different levels of silk’s structure, Buehler says, are analogous to the hierarchical elements that make up a musical composition — including pitch, range, dynamics and tempo. The team enlisted the help of composer John McDonald, a professor of music at Tufts, and MIT postdoc David Spivak, a mathematician who specializes in a field called category theory. Together, using analytical tools derived from category theory to describe the protein structures, the team figured out how to translate the details of the artificial silk’s structure into musical compositions.

The differences were quite distinct: The strong but useless protein molecules translated into music that was aggressive and harsh, Buehler says, while the ones that formed usable fibers sound much softer and more fluid.

Combining materials modeling with mathematical and musical tools, Buehler says, could provide a much faster way of designing new biosynthesized materials, replacing the trial-and-error approach that prevails today. Genetically engineering organisms to produce materials is a long, painstaking process, he says, but this work “has taught us a new approach, a fundamental lesson” in combining experiment, theory and simulation to speed up the discovery process.

Materials produced this way — which can be done under environmentally benign, room-temperature conditions — could lead to new building blocks for tissue engineering or other uses, Buehler says: scaffolds for replacement organs, skin, blood vessels, or even new materials for use in civil engineering.

It may be that the complex structures of music can reveal the underlying complex structures of biomaterials found in nature, Buehler says. “There might be an underlying structural expression in music that tells us more about the proteins that make up our bodies. After all, our organs — including the brain — are made from these building blocks, and humans’ expression of music may inadvertently include more information that we are aware of.”

“Nobody has tapped into this,” he says, adding that with the breadth of his multidisciplinary team, “We could do this — making better bio-inspired materials by using music, and using music to better understand biology.”

At the end of Chandler’s news release there’s a notice about a summer course with Markus Buehler,

For those interested in the work Professor Buehler is doing, you may also be interested to know that he is offering a short course on campus this summer called Materials By Design.

Materials By Design
June 17-20, 2013

Through lectures and hands-on labs, participants will learn how materials failure, studied from a first principles perspective, can be applied in an effective “learning-from-failure approach” to design and make novel materials. Participants will also learn how superior material properties in nature and biology can be mimicked in bioinspired materials for applications in new technology. This course will be of interest to scientists, engineers, managers, and policy makers working in the area of materials design, development, manufacturing, and testing. [emphasis mine]

I wasn’t expecting to see managers and policy makers as possible students for this course.

By the way, Buehler is not the only scientist to make a connection between music and biology (although he seems to be the only person using the concept for applications), there’s also geneticist and biophysicist, Mae Wan Ho and her notion of quantum jazz. From the Quantum Jazz Biology* article by David Reilly in the June 23, 2010 Isis Report,

I use the analogy of ‘quantum jazz’ to express the quantum coherence of the organism. It goes through a fantastic range of space and time scales, from the tiniest atom or subatomic particle to the whole organism and beyond. Organisms communicate with other organisms, and are attuned to natural rhythms, so they have circadian rhythms, annual rhythms, and so on. At the other extreme, you have very fast reactions that take place in femtoseconds. And all these rhythms are coordinated, there is evidence for that.