$2.5 Million Initiative to Develop Chameleon-like Nanoshells

CONTACT: Lia Unrau

PHONE: (713)
831-4793

E-MAIL: unrau@rice.edu

$2.5 MILLION INITIATIVE TO DEVELOP CHAMELEON-LIKE
NANOSHELLS

Developed by Rice University
engineers, metal nanoshells lend a chameleon-like effect to materials and
devices, due to their ability to manipulate different types of light. A new $2.5
million initiative, funded by the Department of Defense, will allow a group of
researchers to study and develop the technology.

The Defense Department has chosen to fund a new five-year
Multidisciplinary University Research Initiative (MURI) headed by Rice
University, and including Oklahoma State University and the University of
Houston, to study and develop the nanoshells, their optical and electromagnetic
responses and properties, and commercial applications.

A number of industries could potentially benefit from the
development of this technology, including electronics, energy conservation,
construction materials, biomedicine and cosmetics.

“The wonderful thing about metal nanoshells is that we can
tailor them to have specific optical properties at different wavelengths of
light,” said Naomi Halas, professor of electrical and computer engineering at
Rice and principal investigator of the project. “The particles themselves have
these properties, an overwhelming advantage over other optical structures, which
require multilayer films or nanoparticle arrays to give rise to similar effects.
Nanoshells can be easily and directly incorporated into coatings and responsive
devices.”

Metal nanoshells are tiny particles, ranging from about
50-1,000 nanometers in diameter, with an insulating core, such as silica, coated
by a thin shell of conductive metal–resembling nano-sized malted milk balls.

Metal nanoshells can absorb light or scatter light, both in the
visible and infrared regions of the spectrum. Varying the thicknesses of the
shell and the core changes the way in which light is manipulated. Variations in
thickness and particle composition extend the controlled electromagnetic wave
response from visible light into the far-infrared and submillimeter-wave
spectral regions.

Nanoshells can be chemically attached to a wide variety of
materials, including plastics, liquids, aerosols, epoxies, glasses and even
fibers. New products could include energy-efficient smart windows, powerful
solar collection and solar cells, coatings for cars, airplanes or buildings,
biomedical sensors, and optical switches, steering light to different points in
futuristic computer architecture.

When incorporated into device structures, nanoshells are
capable of responding to an applied electric current and producing a
voltage-dependent optical response. For instance, by changing the voltage to a
visual display panel built with nanoshell technology, the panel could change
colors or transparency.

Led by Halas, the research team is working to design and create
the metal nanoshells, and to fully understand their properties and abilities.
They will develop arrays, coatings, films and ultrathin films. The researchers
are also studying different types and combinations of materials to improve upon
current inorganic nanoshells and to develop completely organic
nanoshells.

Jennifer West, Rice assistant professor of bioengineering, is
working to develop nanoshell-based all-optical biosensors and biotests. Because
near-infrared light can pass harmlessly through the human body, an implantable
sensor that uses light to monitor chemicals could be used to instantly monitor a
range of different chemicals in the body. In addition, such nanoshell biotesting
devices could be used to check proteins in whole blood, providing a big
advantage over current methods, which are difficult and time consuming.
Customized nanoshell monitors could allow doctors to look at small amounts of
antigens or antibodies and determine rapidly the health of a patient.

Peter Nordlander, Rice professor of physics, is a theoretical
physicist and is studying the electrical transport properties of nanoshells and
how they behave in a variety of environments.

Alex Rimberg, Rice assistant professor of physics, is studying
the way electrons flow around the nanoshells and how the internal structure
affects its electrical transport properties.

Dan Grischkowsky and Alan Cheville, professors in electrical
engineering at the University of Oklahoma, are experts in making measurements in
the terahertz region–the range between infrared light and microwaves–and at
using the unique spectroscopy for probing chemical content of materials. They
characterize the particles that are made and provide insight into how to design
strongly absorbing particles in this region of the spectrum.

As part of the synthetic effort, Randy Lee, a professor of
organic chemistry at the University of Houston, is using synthetic techniques to
grow organic nanoshells, and exploring new methods for the uniform growth of
nanoshell structures.

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Contact: Naomi Halas, professor of electrical and computer
engineering at Rice University, (713) 737-5611, halas@ece.rice.edu.

For more information about Rice’s nanoshell research see:
http://www-ece.rice.edu/~halas/.