SCIENCE AT THE SHINE DOME canberra 30 April – 2 May 2003
Symposium: Nanoscience – where physics, chemistry and biology collide
Friday, 2 May 2004
Dr Vijoleta Braach-Maksvytis
General Manager, CSIRO Global Aid
Co-Director, CSIRO Nanotechnology
Vijoleta Braach-Maksvytis is the Co-Director of CSIRO Nanotechnology. She recently convened Australia's National Nanotechnology Network, to harness the combined capability in science, industry, government, investor, and social sectors. Vijoleta received her PhD in biophysics from the University of Sydney in 1992. She holds over 25 patents in the field of nanotechnology, including co-inventor of the world's first example of a working nanodevice, which won the 1998 Australian Technology Award. From July 2001 to December 2002, she was appointed as the inaugural Chair, CSIRO Science Forum, on the CSIRO Executive Team. Her responsibilities included new emerging science investments, attracting the best young minds into science, and fostering a partnership approach to science. Dr Braach-Maksvytis also holds the position of General Manager, CSIRO Global Aid, and was appointed Head, Office of the Chief Scientist of the Commonwealth of Australia in October 2002.
Inspirations from nature – biomimetic engineering
Nature is a superb example of a nanotechnologist, a nanoscientist in action, and there are some very interesting things about nature that we can learn – the concepts, the principles – both in the way that we make things and in the way that nature actually makes things. It actually does not seek perfection, and that is contrary to where we go in our technologies. Nature goes the other way. It can handle redundancy, it can handle imperfections. How can we learn from that?
What I would like to talk about is in general some of the areas of why we are getting excited about nanoscience and, in particular, the role that nature can play, and to give you some examples of work around the world as well as some of the work that I have been involved in. And I would like to raise some questions which go beyond science, just to leave you with something to think about.
Click on image for a larger version of figure 1
There are two things that people are getting very excited about with nanotechnology. One is that it is like discovering a new class of material. When you take a bulk material and do nothing else but reduce it in size, you start to get very different properties which you cannot predict from the bulk material: it goes from 'classical' to 'quantum' physics. And that occurs with any material. So it really is like a discovery of whole new materials.
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Secondly, the way nature manufactures things and the way we make things are quite different. If you think about how humans make things, we start off with bulk material – a computer chip is a very nice example. We start off with a silicon chip and we carve down, we remove material, to get down to smaller and smaller dimensions. Particularly in the computer area, but also in other areas, we are trying to get down to ever-decreasing and smaller dimensions, and those dimensions are starting to intersect with the nanometre scale.
Nature works in that nanometre scale. But the way it actually creates materials, creates its components on that scale, is not by taking bulk material and carving it down, but from the bottom up – putting the atoms together, putting the molecules together, to produce exactly the functionality, the material, that then continues to grow up into the macro-scale. If we could tap in to that, that would be quite profound in the consequences of materials and all sorts of other areas.
What nature does is to work in air, in water. What we have to do with, say, the silicon chip technology, to remove that material from the bulk material, is to use 800° temperature; we have to use a variety of wastes and solvents that we then have the problem of disposing of. So there are some very interesting capabilities here, if we could actually tap in to what nature does.
If you think of how nature manufactures anything, basically it has a handful of components. It takes some DNA, protein, carbohydrates, lipids, minerals, a pinch of salt, a bit of sugar, and adds water (literally), and you get things as diverse as flowers, people, slugs, humans, dolphins – all from that handful of building blocks, put together in air, in water, by self-assembly. If we could tap in to just a fraction of those principles and create materials and devices, in that same way, then that would create a whole new scenario for us.
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Just to give you some ideas of where people are going for inspiration from nature and exploring that area, consider the butterfly in figure 3 and its exquisite blue phosphorescent colour. If you touch a butterfly you get powder on your fingertips. That powder is actually scales, which are like shingles, on the butterfly's wings. If you look at one of those scales you get structures which, if you cut across them, you see as a series of Christmas trees. And the colour that the butterfly exhibits comes not from a dye but from the way that the light interacts with each of the branches of these Christmas trees.
What is profound about this is that with all of the technology that we have available today, we cannot come close to reproducing these structures. And yet the butterfly, this thing that we squish outside, does this in air, in water, by self-assembly. What is interesting here is that scientists are mimicking some of these structures, on very simple principles, to make new optic communication devices.
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Another nice example is the gecko foot shown in figure 4. The pads of a gecko are actually lined with small structures, and it has been found that the reason a gecko can actually climb up the sides of smooth surfaces and stick to glass walls is that the van der Waals' forces create adhesion at the macro-scale onto the surfaces. And robotics: we are looking at creating pads and robots that can walk up walls, using these sorts of principles.
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But it is more than that. Where we are heading with the biomimetic aspect of nanotechnology is taking something that you are very familiar with and shifting it, looking at it quite differently. An example is DNA. We know of DNA as a biological component, and yet if we think about DNA, it has a double-helix structure and each of the two strands of the double helix likes to find the other. It is like having molecular velcro. Can we use that molecular velcro?
Figure 5 shows nanoparticles attached to single strands of DNA. So you have a surface here, with single strands of DNA attached. Its specific DNA partner has a nanoparticle onto it. Instead of having to position components very precisely down at the single nanometre or subnanometre level – normally done by hand or mechanically with great difficulty – by simply adding a mix of DNA single strands into the solution the hybrid will form with the right partner and position that nanoparticle exactly in the right position. So it is taking something that we know and using it in a different way.
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We would like to make very, very small motors (figure 6). Imagine that, ideally, you could make one a few nanometres in size, it could actually rotate and produce energy – chemical energy, for example, that you could store – and it was biodegradable and ran on light. This is something that a number of groups are working on.
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But all of us, in our mitochondrial cells, already have these sorts of machines – these are biological machines that already exist. In particular, figure 7 shows the F1-ATPase enzyme with a cylinder of six protein subunits and a shaft – another subunit – that rotates.
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At Cornell University they have attached a small silicon motor onto the enzyme, and it is run chemically. So it is a chemically powered battery device. And it is being used to create very small devices as power packs for everything from prosthetics to space research.
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Another simple example is a cell membrane. figure 9 shows diagrammatically the skin of a membrane, like the skin of a balloon. It is made up of two layers of molecules that stack back to back to each other when they are put into water. . Can we actually make use of this assembly method?
Part of my own background was taking that Lego box type of approach with components like lipids and antibodies and proteins, putting all those materials together in water – it took us 10 years – so that they self-assembled to form quite a complicated structure 40 nanometres thick, has a moving slide switch device and can detect basically anything from bacteria to DNA to proteins. And made by self-assembly, just like nature .
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The way it works is that you have this slide switch mechanism, in the absence of analytes you have a flow of ions through these channels, when an analyte is present, however, you get cross-linking – you no longer have the ion flow. So it is a very simple on/off switch.
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But the lamella type structure shown on the left hand side of figure 11, which is what that biosensor was based on, is only one of the sorts of structures that biology uses. There are a number of other structures that form spontaneously in air, in water. If you could use those structures to actually drive the three-dimensional shaping, then you would start being able to tap into nature's ability.
So what we have done with some of our other work is to take things like gold nanoparticles and address how you actually build them up into a three-dimensional structures. We use lipids, those amphiphilic molecules, to actually drive the linking of the particles, and use the self-assembly ability of those lipids to create films which look like gold of a certain thickness.
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However, when we look at the films using a transmission electron microscope they are made up of very discrete nanoparticles, linked together by the amphiphilic molecules.
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When you start making hybrid materials there are different properties that one needs to explore. Figure 13 shows some theoretical basis for some of this work, basically looking at the conduction mechanism of these sorts of nanoparticle films. It is the distance between the two nanoparticles that can control conduction: the closer they are together, the more conduction you will get, and the further away, clearly the quantum barriers occur.
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Using that as a guide, we found that by changing the distance between the nanoparticles from about half a nanometre up to 2 or 3 nanometres, one can actually change the conduction of these films by eight orders of magnitude. So you are talking about an extreme sensitivity, just by manipulating that distance between the nanoparticles. What can you do with these new properties that are starting now to emerge from this, in taking advantage of the quantum effect?
We can change the distance between the nanoparticles by a number of stimuli, whether it is light or electric field or gas. If you can change that distance you start getting into some very interesting sensing type materials.
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Figure 15 is an example here of nanoparticles which are linked by hydrophobic linkers. When you expose them to water nothing happens; if you expose them to a hydrophobic material, for example toluene vapour, you get the expansion and then you get this sensing activity.
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But you can also create materials so they are three-dimensional assembled materials, and you can sandwich them (figure 16). You can use titanium, you can use palladium, you can use silver. The linkers are not limited to particular amphiphilics, you can use anything. And so you open up this very interesting area of materials.
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You can even start getting into non-linear behaviour, which is starting to get into the transistors, basically the printed transistor circuitry area (figure 17).
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So it is this combination of taking the chemistry area, the theoretical physics, the biological area, and pulling that together with some surface physics techniques which are creating these new dimensions, with biological inspiration driving the ordering of these materials (figure 18).
I just want to leave you now with another example of some work that is going on at MIT in the US. An Institute for Soldier Nanotechnology was set up last year. The aim is to create very lightweight bulletproof suits, chameleon – they actually change colour as well – so as to reduce the weight of the packs that soldiers take into the field by about two-thirds. The aim is to create suits that not only are bulletproof, using nanotubes, but also can camouflage soldiers. We have seen how nanoparticles change in the way that they interact with light, and so, taking advantage of that, the way that it reflects and absorbs light can change.
Not only that, the claim is that they are going to make suits that will enable soldiers to leap tall buildings! Where that comes from is again work that is already being done on artificial muscles. Muscles are storage of chemical energy, and pulling that together and releasing it in a single go will enable people to leap tall buildings – which will intimidate the enemy, according to the website.
Not only do these suits, then, have these characteristics, but they will also be able to detect viruses and bacteria. Again it is using sensors that are already out there, and embedding those into the suits. They will also be able to relay soldiers' vital signs back to base, so that people know where they are at, and heal wounds and set breaks. Again that comes from the fact that we know that we can have phase change in materials, going from crystalline phase to liquid crystalline phase. By embedding those sorts of properties into fabrics you can actually get a stiffening occurring, to set a break. And they will then dispense medication as well.
What we are looking at in the future – this is unclassified research – is these suits that basically result in self-sufficient people.
There are a number of questions here that I find very interesting. There is an assumption first of all that only the good guys have this technology. I have been doing some work with the Centre for Applied Philosophy and Ethics, with the Charles Sturt University, and lawyers and a variety of non-scientists. One of the areas that came up is: if there is a reduced risk to troops, what does this actually mean in terms of human behaviour? Will they actually kill more because they don't fear personal harm?
What about something that is closer to home? With these sorts of suits, who needs a doctor if we can detect our own viruses and conditions, and dispense the medication? So there are some interesting changes here for, perhaps, the health profession.
And what about the effects of waste material containing nano-components? That research is only just starting now to come into being, looking at health effects, the environmental effects. When you have materials that have nanoparticles in them and you dispose of them, what happens to those nano-components?
And so there are some very interesting issues that come from working in this field and that we should be addressing now. They may be issues of equity, of privacy and security, the environmental issues. Are nanotubes, for example, the new asbestos? And the whole question of biology–machine integration brings a whole stack of questions in their own right.
I think that we have a unique moment in history, that before the full brunt of the technology is with us there are some very interesting opportunities for us to be a little bit smarter and look at some implications before we have the full potential with us.
I would like to leave you with a quote from Einstein:
Any intelligent fool can make things bigger, more complex and more violent. It takes a touch of genius – and a lot of courage – to move in the opposite direction.
I would like to close with the suggestion that we dare to shape the future a little differently from what we have done previously.
Question: The obvious question, given that ATPase motor, is this: could that machine at short times be violating the second law of thermodynamics?
VB-M: I would love to have that conversation – looking into that issue closely with the ATPase and basically other mechanisms too that biology uses. I think it is a very interesting one.
Question: Doesn't that gadget just take in ATP and put out ADP all the time? It's just an energy consumption.
VB-M: That's right, yes. But it is also a closed loop. One can actually create that as a closed loop, because ATPase is used also in photosynthesis, for example, to drive the CO2 capture to produce carbohydrate. So there are some interesting principles there of using that sort of motor to take greenhouse gases and convert them into food. Some of that work is being looked at by the Artificial Photosynthesis Network here in Australia.
Question: At the end of your talk you were bringing ethics into it. I just have this horrible vision of a bunch of priests sitting down and deciding whether or not we were going to do any research next month on a certain type of nanotube. I think maybe the pendulum is going to swing one way and then the other, and come back into the middle. But I just am very nervous about too many ethicists and priests and various people getting into the scientific equation. I think if you have got a new scientific principle, a new kind of science, a useful advance, it should be able to live like any other discovery or development, and fight its way to the top and decide whether it is going to be superior or not.
The history has shown that trying to predict the future on the basis of current knowledge is practically impossible, and no doubt anything that you decide along those lines is going to be completely outdated in 10 years or 20 years.
VB-M: Bringing up the idea of having a wider discussion and debate about a very new science area should not, I think, be about what should or should not go ahead. It is not a straight black-and-white area. What I am referring to is the lessons from the nuclear debate, the GMO debate, the stem cells debate. People do want to know about what is going on.
There is a very interesting question that is worth debating, about whether science should continue in a role which perhaps is a little outside of society or actually be brought back – dragged – into society as part of it. We use the terminology of science creating an 'impact' on society, and it is almost like the analogy of a meteor travelling by itself and crashing down on Earth: there is a mess or there is an improvement, which someone else deals with, and it continues by itself. I would just like to have a very vigorous debate around that area. I raised that very precisely to create this sort of thinking.
Question: I can give you one example of a consequence of what I think must have been a nanotechnology event. I was told many years ago that a young woman in America was given, for some quite minor but troublesome illness – it might have been the beginning of arthritis or something like that – a silver medication. The consequence was that her whole skin went blue, no doubt by the deposition of silver atoms on her skin, and it was very distressing and very difficult for everybody. It was as if she was permanently tattooed blue. So it can happen. I can't give you a literature reference; it was told to me personally.
