Tag Archives: Markus Buehler

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).

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.

Massachusetts Institute of Technology and bony 3D printing

Markus Buehler (last mentioned here in a Nov. 28, 2012 posting*, about spider silk and music) and his research team at the Massachusetts Institute of Technology (MIT) have been inspired by various biomaterials to create materials that resemble bone matter, from the June 17, 2013 news item on ScienceDaily,

Researchers working to design new materials that are durable, lightweight and environmentally sustainable are increasingly looking to natural composites, such as bone, for inspiration: Bone is strong and tough because its two constituent materials, soft collagen protein and stiff hydroxyapatite mineral, are arranged in complex hierarchical patterns that change at every scale of the composite, from the micro up to the macro.

Now researchers at MIT have developed an approach that allows them to turn their designs into reality. In just a few hours, they can move directly from a multiscale computer model of a synthetic material to the creation of physical samples.

In a paper published online June 17 in Advanced Functional Materials, associate professor Markus Buehler of the Department of Civil and Environmental Engineering and co-authors describe their approach.

The June 17, 2013 MIT news release by Denise Brehm, which originated the news item, explains the researchers’ approach in more detail (Note: A link has been removed),

The collagen in bone is too soft and stretchy to serve as a structural material, and the mineral hydroxyapatite is brittle and prone to fracturing. Yet when the two combine, they form a remarkable composite capable of providing skeletal support for the human body. The hierarchical patterns help bone withstand fracturing by dissipating energy and distributing damage over a larger area, rather than letting the material fail at a single point.

“The geometric patterns we used in the synthetic materials are based on those seen in natural materials like bone or nacre, but also include new designs that do not exist in nature,” says Buehler, who has done extensive research on the molecular structure and fracture behavior of biomaterials. His co-authors are graduate students Leon Dimas and Graham Bratzel, and Ido Eylon of the 3-D printer manufacturer Stratasys. “As engineers we are no longer limited to the natural patterns. We can design our own, which may perform even better than the ones that already exist.”

The researchers created three synthetic composite materials, each of which is one-eighth inch thick and about 5-by-7 inches in size. The first sample simulates the mechanical properties of bone and nacre (also known as mother of pearl). This synthetic has a microscopic pattern that looks like a staggered brick-and-mortar wall: A soft black polymer works as the mortar, and a stiff blue polymer forms the bricks. Another composite simulates the mineral calcite, with an inverted brick-and-mortar pattern featuring soft bricks enclosed in stiff polymer cells. The third composite has a diamond pattern resembling snakeskin. This one was tailored specifically to improve upon one aspect of bone’s ability to shift and spread damage.

The scientists are hinting that they’ve improved on nature and that may be so but I recall reading similar suggestions in studies I’ve read about 19th and 20th century research. It seems to me that scientists have claimed to be improving on nature for quite some time.

Interestingly, the suggested application for this new material is not biomedical, from the news release,

According to Buehler, the process could be scaled up to provide a cost-effective means of manufacturing materials that consist of two or more constituents, arranged in patterns of any variation imaginable and tailored for specific functions in different parts of a structure. He hopes that eventually entire buildings might be printed with optimized materials that incorporate electrical circuits, plumbing and energy harvesting. “The possibilities seem endless, as we are just beginning to push the limits of the kind of geometric features and material combinations we can print,” Buehler says.

You can find a link to and a citation for the published paper at the end of the ScienceDaily June 17, 2013 news item.

* Date changed from 2013 to 2012 on June 4, 2014

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.

Music, math, and spiderwebs

I pricked up my ears when I saw the word ‘analogy’. As a writer, I tend to be quite interested in analogies and metaphors, especially as they relate to science. I certainly never expected to find an analogy established by mathematical rigour—it never occurred to the poet in my soul. Thankfully, mathematicians at MIT (Massachusetts Institute of Technology) were not constrained by my lack of imagination. From the Dec. 8, 2011 news item written by Denise Brehm on Nanowerk,

Using a new mathematical methodology, researchers at MIT have created a scientifically rigorous analogy that shows the similarities between the physical structure of spider silk and the sonic structure of a melody, proving that the structure of each relates to its function in an equivalent way.

The step-by-step comparison begins with the primary building blocks of each item — an amino acid and a sound wave — and moves up to the level of a beta sheet nanocomposite (the secondary structure of a protein consisting of repeated hierarchical patterns) and a musical riff (a repeated pattern of notes or chords). The study explains that structural patterns are directly related to the functional properties of lightweight strength in the spider silk and, in the riff, sonic tension that creates an emotional response in the listener.

The Dec. 8, 2011 news release at MIT goes on to explain,

While likening spider silk to musical composition may appear to be more novelty than breakthrough, the methodology behind it represents a new approach to comparing research findings from disparate scientific fields. Such analogies could help engineers develop materials that make use of the repeating patterns of simple building blocks found in many biological materials that, like spider silk, are lightweight yet extremely failure-resistant. The work also suggests that engineers may be able to gain new insights into biological systems through the study of the structure-function relationships found in music and other art forms.

The MIT researchers — David Spivak, a postdoc in the Department of Mathematics, Associate Professor Markus Buehler of the Department of Civil and Environmental Engineering (CEE) and CEE graduate student Tristan Giesa — published their findings in the December issue of BioNanoScience.

Here’s part of how they developed the analogy between spider silk and music using mathematics (from the MIT news release),

They created the analogy using ontology logs, or “ologs,” a concept introduced about a year ago by Spivak, who specializes in a branch of mathematics called category theory. Ologs provide an abstract means for categorizing the general properties of a system — be it a material, mathematical concept or phenomenon — and showing inherent relationships between function and structure.

To build the ologs, the researchers used information from Buehler’s previous studies of the nanostructure of spider silk and other biological materials.

“There is mounting evidence that similar patterns of material features at the nanoscale, such as clusters of hydrogen bonds or hierarchical structures, govern the behavior of materials in the natural environment, yet we couldn’t mathematically show the analogy between different materials,” Buehler says. “The olog lets us compile information about how materials function in a mathematically rigorous way and identify those patterns that are universal to a very broad class of materials. Its potential for engineering the built environment — in the design of new materials, structures or infrastructure — is immense.”

“This work is very exciting because it brings forth an approach founded on category theory to bridge music (and potentially other aspects of the fine arts) to a new field of materiomics,” says Associate Professor of Biomedical Engineering Joyce Wong of Boston University, a biomaterials scientist and engineer, as well as a musician. “This approach is particularly appropriate for the hierarchical design of proteins, as they show in the silk example. What is particularly exciting is the opportunity to reveal new relationships between seemingly disparate fields with the aim of improving materials engineering and design.”

I always like to have a visual,

Graphic: Christine Daniloff

You can get more details from either the Nanowerk website or the MIT website.

Since it’s a Friday I thought I’d include a video of a song about spiderwebs and found this on YouTube,

Happy Friday!