Bio-engineering - the Nachshon Haim apprentice / interview by Gareth Cook

Chemist Joanna Eisenberg mines the depths of the sea and forest swamps and extracts from them the secrets of nature's planning, knowledge which she uses to assemble new materials that may change our world

One of the first things that catches your eye when you enter Professor Joanna Eisenberg's corner office at Harvard University are the toys. Behind her desk is a sea urchin shell, a framed blue butterfly, a plastic stand from which long fibers emerge that are dyed in a multitude of colors at the push of a button, and rows and rows, not particularly arranged, of toys. Especially many of them are the Hungarian cubes - the classic size of three by three by three, but also those with four, five, six and even seven small cubes on each side. Heaven for eight year olds.

 

Playing with mathematical puzzles is the main occupation, more or less, of the 52-year-old Eisenberg. But its seriousness is indisputable. Eisenberg was born in the southwest of Ukraine, received a degree in chemistry from the University of Moscow, and in 1991 escaped the sexism and anti-Semitism that openly pervaded the Russian academy and started a bright career in the West in the field of bioengineering. She reveals the planning secrets of Mother Nature and uses them in her work. Eisenberg works in a combined position at several institutions of Harvard University: the School of Engineering and Applied Science, the Radcliffe Institute for Advanced Research and the Weiss Institute - a new research center for engineering inspired by nature in which $125 million has been invested.

Eisenberg approaches her research with a playful approach. She crosses familiar boundaries between traditional scientific disciplines with the fearless enthusiasm of a child. She became famous mainly for her collaborations with biologists who discovered unusual engineering principles used by creatures in the depths of the sea. But she also works (or plays) with chemists and architects, physicists and toy designers.

Here are selected excerpts from our conversation with you.

Scientific American: Why do you look for inspiration in nature?

Eisenberg: In every biological system I see a new and amazing example of sophisticated planning. Nature has developed so many interesting strategies. Nature has created all kinds of quality materials and facilities that scientists simply do not know exist.

See for example the sea urchin, which is a relative of the sea star and the sea urchin. He has hard armor, and was always thought to be blind. But we discovered that part of his armor is studded with lenses - he can see through his armor. During the day it dims the light that hits the lenses using a dark pigment, but at night it absorbs the color into its body. You can say that Nachshon Hayam wears sunglasses, and their lenses are better than the lenses we know how to make. This is an example of an important principle: in the living world it often happens that a certain substance is optimally used for several different purposes. The armor is characterized by excellent mechanical properties, as it is a skeleton, but it is also built for optical action. From an engineering point of view, these two roles are as far apart as east from west, and here this creature combines the two in one structure.

We therefore study interesting biological systems, but from the point of view of the physical sciences. This approach will pave the way for the development of new materials and devices that can change the world.

 

Tell me about your work with the deep water sponge.

It is an amazing creature in every way. He lives on the bottom of the ocean and grows himself a skeleton of glass. When humans make glass, they do it at 2,000 degrees Celsius, but these creatures somehow make the glass fibers at room temperature.

Also at the base of the sponge, where it clings to the bottom, there is a crown of thin strands that behave like almost perfect optical fibers that conduct light from one end of the fiber to the other. Humans think they invented the optical fiber about 60 years ago, but it's been half a billion years that nature produces optical fibers from the material from which we make them.

But why does the sponge need such a complex optical system? He lives in the dark. It turns out that he lives in symbiosis. Glowing bacteria live on top of the sponge, and the light they emit travels through the fibers. The shining fiber crown serves as a beacon that attracts more animals from the Alta. On top of that, a pair of snails lives inside the sponge. He is protected in this lighted glass house and feeds on all the creatures that are attracted to the light. The secretions of the shrimp are part of the sponge's food. It's a complete system.

How did you discover the sponge?

I attended a scientific conference in San Francisco and went to a gemstone store. I am addicted to such stores. And there was such a sponge. He was lying in a very dark corner, and his fiber crown was all glowing. The sight was so beautiful. I went ahead with it and did what I really love to do: I collaborated with marine biologists.

What do you think we can learn from this creature?

The deep water sponge can teach how to strengthen materials that are weak and delicate by nature. The glass is fragile, but this sponge is not fragile at all. You can step on it and nothing will happen to it.

Nature achieves this result by combining several structural strategies on top of each other. It groups fibers into a multi-layered material. The fibers build pegs that join each other and form squares that are wrapped in glass fiber cement. Glass inside glass inside glass. But the sponge combines all the structures of the glass together and a very strong material is created that overcomes the natural fragility of the glass.

It is also possible to imagine the sponge as a "green" building with a model of open windows on its outer walls. It makes me wonder, for example, if it is possible to build a skyscraper where every tenth floor is open and allows wind energy to be utilized.

From the point of view of the engineers, what are the benefits of observing nature and what are the pitfalls that may lie in this?

Nature can offer engineers a huge variety of solutions to complicated technical problems. Not all solutions are practical. It may turn out, for example, that this or that approach inspired by nature is so expensive in materials and energy that it is therefore impossible to use it. However, it is possible that natural solutions will be found that do not fall short of today's engineering solutions, or fall slightly short of them, but their implementation is much cheaper. In other words, nature provides a wide range of solutions that can be studied and explored.

But you have to be careful. The selection of materials in nature is very limited. There is no steel in the living world. In our world there are and there are. That's why I don't like to call my field of research "biomimetics" (imitation of nature) because I don't want to imitate the biological structures. I prefer the term: "engineering inspired by nature" because what I do is draw concepts and ideas from the biological content, rather than specific solutions. I would not like to build a sea shelter, but a mechanically stable roof that contains light collecting lenses. I will not use the materials that Nachshon Haim uses, but I will take the strategy from him.

How is it that nature is such a talented engineer?

The animal world revolves around function: every organism must create solutions that will deal well with the problems before it: how to divide, how to heal or how to create things that will last. Nature also enjoys one great advantage: millions of years of evolution. We don't have that long. Another factor is that in the animal world there are no choices. Only the fittest survive. The bad engineers are extinct. A mistake means a mistake.

Did your parents have an influence on you being a scientist?

My father was a civil engineer. He designed and built bridges and roads. My mother was a doctor who specialized in infectious diseases. I have drawn inspiration from both of them in many ways. My mother studied medicine in the 50s (in the Soviet Union). In those days, Stalin banned any practice in genetics, and she headed a group of students who met secretly and studied DNA. She was fearlessly made. I have never known a person with willpower like hers.

When I was little I got polio, and my legs were paralyzed for a long time. My mother set aside a lot of time for conversations with me. She showed me the world that peeked through my window. "Look at how the trees grow, look at the shapes they create," she would say. "Look at the patterns the water creates when it flows in torrents." It was really wonderful.

What got you interested in chemistry?

It might sound a little strange, but one of the things I loved doing as a child was solving invoice puzzles. When I was in middle school I even made a little money from a magazine that paid me to put together puzzles for the other students. When I arrived at Moscow University, I met people who studied mathematics, physics and chemistry. From the conversations with you I came to the conclusion that mathematics is only mathematics, physics is only mathematics and physics, while the field of chemistry is very broad. And the more I studied chemistry, the stronger I felt that chemistry is the science in which the key lies. It branches in every direction. It's an amazing place to be.

Does everything you do start with some plant or animal that interests you or do you sometimes start with a specific application in mind?

My research group became interested in the field of "wettability", which deals with the question of how much a material repels or attracts water. We would like to learn to control the degree of wetting of surfaces. For 15 years, they all drew inspiration from the lotus plant, as the water flows over it and washes off naturally [see self-cleaning materials, Scientific American Israel, December 2008]. But those involved in the field already know that applying the secrets of the lotus for practical purposes will be very difficult. These materials, it turns out, are too expensive and not durable enough.

That's why we turned to another model from the natural world: the pitcher plants. These are carnivorous plants equipped with a "jug" whose inner side is unbelievably slippery. An ant climbing into its opening will immediately slide in, be trapped and digested. Inspired by this surface, we built a similarly slippery surface. It can be used to coat the inner walls of oil pipes, and this will greatly facilitate the pumping of oil and its flow. In terms of biomedical applications, the substance can help blood flow well and prevent the growth of bacterial colonies. Another possible use is graffiti resistant wall covering. The paint will just slide off of it. This will greatly upset these artists.

What do you think material science will invent for us in the coming decades?

We know how to make strong materials, we know how to make optical materials, but we are bad at producing materials that react to the environment, materials whose properties change automatically, that can repair themselves, that can change their shape when needed. We need materials with reversible adaptive behavior.

We have, for example, a material that can be used for "smart" clothing. It changes automatically according to the humidity conditions of the environment. It attracts moisture to it when it is very dry outside, but repels water when it rains. You can imagine the many uses that adaptive materials can have. When it's cold outside you want the windows to conduct heat into the room as much as possible, but on a hot summer day you want the same material to reflect light and maintain a pleasant temperature inside the room.

The invention of such materials is the great challenge of the 21st century.

After learning so much about the animal world, do you look at it in a different light?

You can say yes. I am very interested in the formation of patterns. That's why when I walk on the beach, I constantly look at the way the waves reach the beach. I can also look throughout the trip at the lines that the receding waves leave behind in the sand. They create beautiful shapes. It makes me think about the relationship of these shapes to other beaches or the size of the grains of sand.

I really like the sea. Life there is so diverse and amazing. And I'm sure that we can learn something from every living being.

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About the author

Gareth Cook (Cook) is a Boston Globe journalist, Pulitzer Prize winner and editor of the "Mind Matters" neuroscience blog of the journal Scientific American Mind.

in brief

Joanna Eisenberg

occupation | hobby

Management of a biomimetics laboratory

where

Harvard University

specialization

Invention of new materials inspired by the animal world

big time

"We study interesting biological systems, but from the point of view of the physical sciences."

And more on the subject

Harvard Portrait: Joanna Aizenberg. Harvard Magazine, page 59; July/August 2008. http://harvardmagazine.com/2008/07/joanna-aizenberg.html

Bioinspired Self-Repairing Slippery Surfaces with Pressure-Stable Omniphobicity. Tak-Sik Wong et al. in Nature, Vol. 477, pages 443-447; September 22, 2011.

The Aizenberg Biomineralization and Biomimetics Lab: http://aizenberglab.seas.harvard.edu/index.php

To watch a film about Eisenberg's work to produce a surface that prevents freezing, visit the website www.sciam.co.il

 

On site only

Eisenberg's lab delved into understanding the physics of water to design a specially structured coating polymer that completely repels ice build-up at temperatures down to minus 30 degrees Celsius. This material, or a similar material that will be developed later, could one day be used to coat airplanes, high voltage poles or roofs of buildings.

Watch this amazing video of a drop of water splashing off a superhydrophobic, anti-freezing surface in Eisenberg's lab. For comparison, you can see two other surfaces at the beginning of the film: the first is hydrophilic and the second is "just" hydrophobic.