Nano Gold
JB: This is Earth and Sky for Monday, February 9. Nanoscience involves the realm of the small. A nanometer is a billionth of a meter wide.
DB: Chad Mirkin is Director of the Institute for Nanotechnology at Northwestern University. He’s working with particles on the scale of about 100 nanometers.
Chad Mirkin: It turns out that if you take any material, regardless of what it is – gold, silver, platinum, semiconductor materials, insulating materials – if you shrink them down to the sub–one hundred nanometer length scale, they will have a new set of properties. Gold is a beautiful example of that – shiny, metallic material when it’s a bulk material. You shrink it down to 30–nanometer particles, and it’s now a very intense red color.
JB: Slightly smaller gold “nanoparticles” are brownish – a bit bigger and they’re purple. Nanoscience – the sciences of the very small – sounds new. But, in some ways, it isn’t new.
Chad Mirkin: Some people would say people were doing nanotechnology back in the middle ages, because they used gold particles, for example … as red dyes for stained glass windows. Now, in reality, they didn’t really know what they were doing.
DB: Now scientists have tools and methods that let them manipulate nanoparticles with greater control. More tomorrow. Our thanks to the National Science Foundation – where discoveries begin. We’re Block and Byrd for Earth and Sky.
Excerpts from an interview with Chad Mirkin:
Nanotechnology is a field that in many respects got its birth in science fiction, where people talked about the wonderful consequences and capabilities associated with miniaturization. Perhaps one of the best examples of that is Isaac Asimov’s “Fantastic Voyage”
Usually we think about miniaturizing things by chiseling and shrinking them down and then looking at the capabilities afforded by shrinking them. It turns out that if you take any material, regardless of what it is – gold, silver, platinum, semiconductor materials, insulating materials – if you shrink them down to the sub–one hundred nanometer length scale, they will have a new set of properties 2.52 gold is a beautiful example of that – shiny, metallic material when it’s a bulk material. You shrink it down to thirty–nanometer particles, and it’s now a very intense red color – Do those small particles happen in Nature?
Yeah, it turns out that is some cases they do … when we talk about, when did nanotechnology get it’s start – some people would say people were doing nanotechnology back in the middle ages, because they used gold particles, for example, as red dyes for stained glass windows. Now, in reality, they didn’t really know what they were doing. They didn’t have tools or instruments that would allow them to visualize and build structures on that scale so that they could intentionally design materials that had a set of properties that were useful for whatever application they intended to use them for.
So the real opportunity, in terms of nanoscience and nanotechnology, is realizing that when we shrink materials down to this length scale, or build them from atoms up to that length scale … there are going to be new materials with new properties and those new properties can form the basis for new applications.. and that transitions nanoscience into nanotechnology
If you take a gold salt … you can reduce it, and as gold goes from gold three to gold zero, the atoms begin to clump together and bunch together and form little particles. And by controlling that process you can build particles or synthesize particles with control over diameter – because they’re spherical particles – and when you do that, if you control the diameter, you can control their properties. Turns out, if you make them really small, they’re kind of brownish in color. If you make them moderately small – let’s say the twenty to thirty nanometer range – they’re red in color. If you make them a hundred nanometers in size, they’re purplish in color.
Nanoscientists typically refer to themselves as doing science from the bottom up rather than the top down. A top down approach would be to take bulk gold and learn how to carve it down or miniaturize it using tools that would shave away atoms until you had a really small structure with a unique set of properties because it now falls within this [one hundred] nanometer length scale. The bottom up approach would be to take a source of individual atoms of gold and learn how to control their assembly or aggregation into larger clumps of gold that form what we call nanoparticles.
A big challenge here is to learn how to do this for all sorts of materials. We want to learn [A FAINT BELL HERE] how to become nano–architects. We’d like to not only be able to control size but composition, and shape. It turns out that if you make these particles triangular in shape, they have different from the spherical particles. If you make them rod–like they have different properties from the triangles and spherical structures.
We are in the stone ages. But the difference is we have very powerful tools that will decrease the timeline associated with the development of nanoscience and nanotechnology. This is really a tool–driven field
As these new tools develop, it will be all encompassing. It’s going to change the way we do all material science. It’s going to change the way we do all chemistry, the way we do all physics.
Often, when you look at all the different ways of defining nanoscience and nanotechnology– pretty soon it becomes everything.
If you have a tool which allows you to make materials on this length scale … what a phenomenal IP – intellectual property – discovery tool, what a phenomenal scientific tool, because everything you make is going to have new properties, is going to lead to new science.
The following individual was interviewed for today’s show. Our thanks to:
Chad Mirkin, Ph.D.
Professor of Chemistry
Director, Institute for Nanotechnology
Northwestern University
Chicago, IL
