Gold 'Nanostars' Could Be Ultra-Sensitive Chemical Sensors

April 18, 2006
'Nanostars' could be ultra-sensitive chemical sensors
The nanostar's 3-D spikes are visible in this image from a transmission electron microscope. Credit: Jason Hafner/Rice University

New optics research from Rice University's Laboratory for Nanophotonics suggests that tiny gold particles called nanostars could become powerful chemical sensors.

The findings are available online and due to appear in an upcoming issue of the journal Nano Letters. Nanophotonics is a rapidly growing field of study that looks at ways to generate and manipulate light using ultrasmall, engineered structures. The virus-sized nanostars, so named because of their spiky surface, are one of a growing number of intricately shaped particles that are increasingly drawing the attention of experts at LANP and other leading photonics labs.

"Just a few years ago, everyone's attention was on the size of nanoparticles because altering size was a straightforward way to change the wavelength of light that the particle reacted with," said lead researcher Jason Hafner, associate director of LANP and assistant professor of physics and astronomy and of chemistry. "Today, researchers are increasingly interested in intricate shapes and the specific ways that those shapes affect a particle's interaction with light."

Most nanophotonic research at LANP involves the study of plasmons, waves of electrons that flow like a fluid across metal surfaces. Light can be used to amplify plasmon waves on metal nanoparticles. Like a child in a bathtub, rhythmically building waves until they slosh out of the tub, the plasmons on the particles dramatically amplified with wavelengths of light that correspond to the rhythm of the electron waves. The study of plasmonics is one of the fastest growing fields in optics because it could prove useful for a wide range of applications in biological sensing, microelectronics, chemical detection, medical technology and others.

"LANP is building a broad-based plasmonics research program at Rice, and our recent cutting-edge work on novel structures like nanostars and nanorice is a clear indication of leadership we're building in this field," said LANP Director Naomi Halas, the Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry.

Nanostars incorporate some of the best properties of oft-studied photonic particles like nanorods and quantum dots. For example, they deliver strong spectral peaks that are easy to distinguish with relatively low-cost detectors. But Hafner's team found unique properties too. A painstaking analysis revealed that each spike on a nanostar has a unique spectral signature, and preliminary tests show that these signatures can be used to discern the three-dimensional orientation of the nanostar, which could open up new possibilities for 3-D molecular sensing.

"We are just getting started with our follow-up work, but nanostars clearly offer some exciting possibilities," said Hafner, assistant professor of physics and astronomy and of chemistry. "Their extreme sensitivity to the local dielectric environment is a particularly attractive quality for molecular sensing."

Source: Rice University

Explore further: Team demonstrates solar water-splitting technology

Related Stories

Biomimetic photodetector 'sees' in color

August 25, 2014

( —Rice University researchers have created a CMOS-compatible, biomimetic color photodetector that directly responds to red, green and blue light in much the same way the human eye does.

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

A blue, neptune-size exoplanet around a red dwarf star

November 25, 2015

A team of astronomers have used the LCOGT network to detect light scattered by tiny particles (called Rayleigh scattering), through the atmosphere of a Neptune-size transiting exoplanet. This suggests a blue sky on this world ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.