Nanotechnology:
The Promise and the Hype
Seán Barry,
Nanoscience Working Group,
Department of Chemistry,
Carleton University
The Scale of “Nanoscale”
1 – 100 nm
1x10-9 – 1x10-7 m
across Canada → a centimetre
Microscopy: scanning electron, transmission
electron, and atomic force microscopy
2
What Nanotechnology is Not
Modern
nanotechnology is not
the fabrication of tiny
mechanical devices
the can and will enter
human systems to
repair or damage
cells.
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Real “Nanomotors”
“machine-like” nanoscale
behaviour
A tiny blade of gold attached to
a carbon “nanotube”, and an
electrical current allows it to
spin.
Nature 2003 424, 408.
4
History of Nanotechnology – First Example
The “Lycurgus
Cup” is a Roman
artifact from
before 640 AD.
It is dichroic, changing colour when illuminated from
the inside. This effect is caused by gold and silver
nanoparticles, and was likely produced by accident.
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History of Nanotechnology – Stained Glass
As early as 500 AD,
glass artisans were
making stained glass
windows with vibrant
reds and yellows.
These colours were
much more luminous
and durable than dyes
could produce.
They were the products of “coinage metal”
nanoparticles imbedded in the glass.
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History of Nanotechnology – Coinage Metals
As these nanoparticles
get smaller, the colours
shift from red, through
yellow and green, to
blue.
Here is an example of a copper nanocrystal
that is roughly 100 nm across.
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History of Nanotechnology - Photography
In 1827, Joeph Niépse
was able to stabilise
silver halide nanocrystals
in a gelatin that
hardened with exposure
to light.
The silver halides
decomposed to silver
metal, producing black.
The crystal grains were too small to be discerned,
and so black-and-white photography gave
excellently resolved photos.
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History of Nanotechnology - Colloids
Nanoparticles “stay in solution”, leading to one of
the most enduring images of nanotechnology:
The rainbow array of solutions made by the
suspension of a variety of sizes of nanoparticles.
This was discovered by Michael Faraday in 1857.
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Impact of Nanotechnology
The benefit of nanotechnology is the
ability to introduce new characteristics
from materials:
•Antibacterial behaviour
•Colour
•Conductivity
•Tensile strength
•Chemical behaviour
•Interaction with water
•“Self-cleaning”
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Impact of Nanotechnology
In Canada, there are 80
companies that make 150
products that use 88 different
nanomaterials.
Worldwide, there are about
580 products made by 305
companies in 20 countries.
Keep in mind that several of these share a
technology, and many others are “reclassified” as
nanotechnology.
http://smarteconomy.typepad.com/smart_economy/2008/02/outsourcing-and.html
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Modern Nanotechnology - Microelectronics
The Xbox 360 is one of the most
prevalent microelectronic
technologies to employ
nanotechnology.
The method is “silicon-on-oxide”,
which makes 100 nm silicon
layers. This allows for a
decrease in microelectronic
device size, and so an increased
density within a chip.
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Modern Nanotech - Sunblock
Zinc oxide and titanium oxide are
both employed as opaque
sunblocks.
When particles are nanoscale, they
become invisible to the human
eye, but still reflect UV light.
Modern sunblocks can provide
a physical barrier without this
classic appearance.
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Modern Nanotechnology – Antimicrobial Fabric
Nanohorizons, a company in the
Pennsylvania, has started
producing a silver nanoparticle
material as both a dye and in
polyester and nylon.
The silver nanoparticles are
toxic to microbes, and so
colonies will never form, and
clothes using this material will
not have odours.
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Modern Nanotechnology – Golf Balls
Nano Dynamics in the US has
produced a golf ball
incorporating nanotechnology.
Although they are tight-lipped
about what the material is, the
inner metallic coating is likely
nanoparticles of a coinage
metal.
The elasticity (and response to a golf club) is
different that a traditional core, and this will affect
the aerodynamics.
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Future Directions - Solar Panels
Newer solar panels now
incorporate “nanocrystalline silicon”.
This increases efficiency by
“bouncing” the light around.
Upcoming solar cells incorporate
nanostructures (rods, ribbons,
particles) of different materials
to increase the efficiency of these
cells.
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Future Directions - DNA as a Nanomaterial
Uncoiled DNA strands are
centimetres long, and are
like polymers.
They can be modified to
“cross-link” in such a way to
define shapes.
These impressive images are 165 nm by 165 nm.
Nature 2006, 440(16), 297.
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Singularly Impressive
Nature 2006, 440(16), 297.
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Future Directions - Nanophotonic Sensors
Mines and other enclosed
environments could use fibre
optic sensors to detect
pollutants.
An ultrathin layer of metal
(typically a coinage metal)
will allow specific polutants to
adhere to the surface, but
light could still see through to
detect them.
This would allow real-time,
on-person environmental
monitoring.
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Nanoparticle Biosensors
Antibodies can be anchored to nanoparticle
surfaces to collect specific proteins.
In this example, the nanoparticle is magnetic,
allowing it to be separated and analysed.
Clinica Chimica Acta 2005, 358, 37
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Nanotoxicity
Copper
Microscale
(17 g)
Nanoscale
(23.5 nm)
Ionic
(0.072 nm)
Particle number LD50
(per  g)
(mg/kg)
44
5610
10
413
9. 4×1015
110
1. 7×10
Toxicity class
Nontoxic Class 5
Moderately toxic
Class 3
Moderately toxic
Class 3
There is an indication that nanoparticles interact
with biological systems like molecules.
J. Nanosci. Nanotechnol. 2007, 7, 3048.
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Introduction to Biological Systems
recycling
Production
Production
(raw)
(consumer)
worker exposure
Industrial and municipal
discharge
EPA Nanotechnology
White Paper 2007
Use
Disposal
(end of life)
consumer
exposure
Landfills and
Incinerators
Human and ecological systems
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Solutions to Toxicity
Previously, magnetic iron oxide
(SPION) was shown to enhance
magnetic imaging.
However, normal SPION is toxic.
When coated with a sugar
derivative (Pullulan), it was found
to be non-toxic.
Biomaterials 2005, 26, 1565.
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Modification and Study
Healthy cells.
Cells incubated with iron
oxide nanoparticles.
Cells incubated with pullulancoated iron oxide
nanoparticles.
Biomaterials 2005, 26, 1565.
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Summary
• Nanotechnology is not very new.
• but our ability to image it (and so, modify it) has increased.
• Nanotechnology will modify existing technologies, and
enable new ones.
• But (likely) not radically.
• Health applications drastically improve imaging, drug
delivery, and many other aspects.
• Health concerns are presently being studied.
• Cautious and well-reasoned employment of nanotechnology
will improve quality of life.
• Research (as always) is ongoing.
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