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Professor Frank Caruso was interviewed in 2002 for the Interviews with Australian scientists series. By viewing the interviews in this series, or reading the transcripts and extracts, your students can begin to appreciate Australia's contribution to the growth of scientific knowledge.
The following summary of Caruso's career sets the context for the extract chosen for these teachers notes. The extract highlights Caruso's interest in nanoparticles and how they can be modified and used. Use the focus questions that accompany the extract to promote discussion among your students.
Frank Caruso was born in Plantania, Italy in 1968, and moved to Australia as a child. He completed an honours degree in physical chemistry at the University of Melbourne and in 1994 received a PhD for his research into the dynamics of molecules. He then took up a postdoctoral fellowship at the CSIRO Division of Chemicals and Polymers, where his research involved the modification of surfaces to enable the detection of specific molecules.
In 1997 he was awarded an Alexander von Humboldt Research Fellowship to work at the Max Planck Institute of Colloids and Interfaces in Berlin. Here he developed a strategy to modify the surface of nano-sized colloid particles by coating them with layers of other materials, using the technique of self-assembly.
In 2002, Caruso received a Federation Fellowship from the Australian Research Council to return to Australia as Professor in the Department of Chemical and Biomolecular Engineering at the University of Melbourne. Here he will continue his work on novel, small particles, as well as thin films derived from these particles. He is interested in looking for new ways to use these nanoscale materials in the areas of biotechnology and nanotechnology.
Caruso's research has been well recognised. In 1998 he received a Max Planck Institute award for research excellence and an award from the German Federal Ministry of Education, Science, Research and Technology. In 2000 he was awarded the Royal Australian Chemical Institute Rennie Memorial Medal for the most significant contribution to a branch of chemical science, and in 2001 received the Royal Society of Chemistry-Royal Australasian Chemical Institute Exchange Medal.
Did you make any scientific breakthroughs while you were in Berlin?
There were a number of scientific breakthroughs that have been considered as significant. Some were basically on how to modify colloid particles – even very, very small particles in the nanometre regime, between about 50 x 10-9 metres and about 100 nanometres in diameter. We developed a very versatile and flexible strategy to modify the surfaces of these particles and introduce new functionalities to them, using self-assembly. And in doing so we have created a whole range of new colloid or nanocomposite particles that we are now interested in using to self-assemble into other structures to fabricate advanced materials.
The effects of reducing materials to the nanoscale
Let’s look a bit more closely at some of the concepts you have been referring to. For example, how do things behave differently at the nanometre scale?
An example related to my group’s area of research would be metals. Many people would be familiar with the fact that a gold metal film can be reflective and has a yellowish appearance. If you have the same material sized down in the form of particles in the nanometre range, these particles exist, for example, in an aqueous solution and they can be red in colour. So they have totally different optical properties – on one hand you have a yellowish reflective coating; on the other hand, in the nanoregime, it is a colloidal dispersion, which to the eye appears red. That is an example of extreme differences that arise. And there are many analogous examples of differences in optical properties, in electronic properties, in magnetic properties and others, simply as a result of going down in size for these and other materials.
So a lot of nanotechnology is about trying to work out and exploit the properties of the substance when you take it from its bulk form and reduce it to nanometre-size particles?
Yes. That’s precisely what is interesting in nanotechnology, that material at the nanoscale level behaves very differently from similar material which is not at that scale. And one can utilise those properties to create advanced systems, structures, materials, for various applications.
Manipulating nanoparticles and nanosystems
How do you manipulate objects at the nanometre scale?
This is very challenging. A variety of techniques are used. Some involve state-of-the-art instruments – specifically-designed microscopes and others – but self-assembly, under controlled conditions, can also be used to manipulate some of these materials.
Self-assembly is essentially the ability for compounds or species, or materials for that matter, to assemble by themselves into various structures. Nature is full of examples of self-assembly, for example coral, a whole range of different materials. Self-assembly is very important because it enables us, in many instances, to prepare structures that otherwise we would not be able to. New avenues and methods are becoming available now to manipulate nanoscale systems in order to form advanced structures, but self-assembly provides a flexible and viable approach to creating structures by taking these nanoparticles or nanosystems and allowing them to assemble, on their own, into a desired final material or product.
So, for example, if you take a surface and pattern it with various functionalities, then you can assemble some of these nanocomponents onto certain areas on that surface. You can use pre-formed surfaces or you can use specially designed mechanical manipulators, but it is extremely challenging. This is where I believe there are going to be significant advances in the near future.
In our research we manipulate the materials through controlled assembly, in essence modifying the properties of the colloidal dispersions, through salt and pH – acidity, basicity of the solution – and that enables the dispersions to behave differently.
Possibilities presented by colloid particles
So what are colloids, and why is it important to be able to modify their surface properties?
Colloids are particles dispersed in a different phase, and they are present all around us, for example in milk, paints and also fog. The simplest case, of particles dispersed in water, is known as a colloidal dispersion. And if you would like to administer drugs to a body, for example, you can have colloidal drug delivery systems. If you can nanoengineer particles – that is, introduce new properties, new functions to those particles – you can manipulate those particles in terms of how much drug can be loaded and how the drug can be released in various applications. That then should have immediate translation to medicine in the area of drug delivery. That simple example is a very important one, as there is immense scope for improvement, just in being able to modify and control particles in solution.
Are you talking about loading the drug into these colloid particles?
Yes. There is a variety of colloids that one can make or modify. Some of these can be solid colloid particles, or they can be hollow. In the case that they are solid, one can imbed the drug within the particle; in the case that they are hollow, one can infill the particle with the drug. So you can infill or you can imbed in a different matrix or material, and then release those under certain conditions.
Focus questions
Select activities that are most appropriate for your lesson plan or add your own. You can also encourage students to identify key issues in the preceding extract and devise their own questions or topics for discussion.
advanced materials
colloids
nanotechnology
self-assembly
surface chemistry
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