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| CSIRO | SOLVE | Issue 10 | FEB 07 | |
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ARTICLE
MATERIALS SCIENCE:
Nano Future Beckons By Tony Kaye
In the vanguard of nanotechnology, CSIRO is leading the way to new renewable energy and health technologies.To many, nanotechnology is the new industrial revolution; the fabrication of materials such as metals and polymers at the molecular level, giving familiar materials completely new properties. It is an area where research and applications are telescoping into each other, such is the momentum building as this new manufacturing frontier becomes better understood. One early commercial example of nanotechnology has been to coat the inside of refrigerators with bacteria-killing silver nanoparticles. In cancer research, nanoparticles are being designed to bind to cancer cells, making them visible to molecular imaging devices. This allows doctors to actually see if they are killing the cancer cells or just slowing them down. The global market for nanoparticles has jumped from US$7 billion in 2002 to a forecast US$29 billion by 2008. The US National Science Foundation recently predicted a US$1 trillion global market for nanotechnology in little more than a decade. Through the work of a group of scientists working across four CSIRO divisions, Australia is in the vanguard of this development. By pooling their skills to explore new nanotechnologies with applications in health, energy and the environment, they have high hopes for a substantial and long-term pay-off for Australian industry.
The team, including Dr Matthew Hill, Dr Edith Chow and Dr Guozhen Liu, has joined the ‘hierarchical materials emerging science’ area championed by Dr Calum Drummond, chief of CSIRO Industrial Physics. Essentially, their goal is to create building blocks at the nano-scale to develop hierarchical materials – particulate substances that have a three-dimensional structure on multiple length scales. These materials are highly porous, containing ‘holes’ of different sizes, which are used to create functionality by trapping and releasing substances in a controlled manner. The different pore sizes can also be used to engender different properties simultaneously, delivering a multifunctional end-product. Creating the hierarchical structures involves making nano-size moulds with various-sized holes, from a nanometre (one-millionth of a millimetre) to tens of nanometres, up to about a micron (one millionth of a metre). Energy storage is one application being pursued by CSIRO, with the research team developing new types of hierarchical materials through a novel chemical synthesis technique called nanocasting. This is expected to facilitate the manufacture of energy storage devices such as supercapacitors. These are already part of the world’s pursuit of renewable energy sources. The stumbling block is that these sources do not deliver energy at a constant rate, hence the need for a mechanism for storing the energy until required. Dr Hill says the team has had 'interesting results' from prototype hierarchical materials they have developed, and from testing their properties. “The different-sized holes in the hierarchical materials can be used to put a range of functions into the material at the same time,” Dr Hill says. “Nanometre-sized holes are good for storage of electrical charges for later release, and micron-sized holes help transport an electrolyte throughout the material, which can be used to carry the electrical charges out when the energy is needed. “By having both of those sized holes there at the same time you have much better properties for your energy storage device, whereas with most other materials you can only have one or the other. “The general thrust for these storage devices is to tie in with renewable energy, so that where something doesn’t produce a constant rate of electricity you can store and release it when you need it. That’s the ultimate goal.” Dr Guozhen Liu says drug delivery is another area of the research, using hierarchical materials that can trap and deliver drugs in a more controlled manner than oral or intravenous delivery methods. Acting as a nanoscale sieve, which may be a film that can be spread on the skin, a hierarchical material can allow drug molecules to slowly slip through the various pores, to target a particular disease with a continuous flow of a drug molecule at an adjustable rate and concentration. “With drug delivery, the smaller holes of a hierarchical material are used to trap the drug and the larger holes allow it to be later released at a controlled rate,” Dr Liu says. “You can then have a slow release of a drug from within a hierarchical material into the body, so it works more effectively in treating a patient. We are applying general chemical processes but scaling them down by a factor of a million times.” Another area being researched by Dr Edith Chow is the use of specially created hierarchical materials such as gold nanoparticles for chemical sensing, particularly for testing environmental quality and searching for levels of water pollutants. “The electronic properties of the sensor can be controlled by modifying the structural coating and porosity of the nanoparticle so that the sensor can be targeted for a particular pollutant,” Dr Chow says. “However, to detect a range of pollutants a diverse range of different nanoparticle sensors are required.” The approach towards fabricating a large number of sensors is through a combinatorial chemistry technique that allows the simultaneous creation of new functional materials. Combinatorial approaches are favoured because scientists are constantly trying to accelerate the development and characterisation of new materials. While the research in hierarchical materials has been promising, commercial developments are still some way down the track. “We are talking with various companies, even though commercialisation is some way off,” Dr Chow says. Dr Liu says one of the advantages in terms of eventual application is that the scientific team is working across four divisions of CSIRO, so the spread of knowledge is quite broad.
“We are all young scientists in our first few years of research and we’ve started in this emerging area of hierarchical materials and working on these materials for different applications,” Dr Liu says. “Essentially what we’re trying to do is approach these problems with different fields of expertise and solve them through teamwork. “It is exciting to develop these new hierarchical materials that will find application in areas of great importance to all of us, such as medical treatments, renewable energy sources and maintaining a clean environment.” For further information contact: |
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