Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rice University researchers create ’nanorice’

15.03.2006


Nanoparticle’s shape could improve chemical sensing, biological imaging


Nanorice is made of non-conducting iron oxide called hematite that’s covered with gold. The core size and shell thickness vary slightly but the particles are about 20 times smaller than a red blood cell.



Who better to invent "nanorice" than researchers at Rice University? But marketing and whimsy weren’t what motivated the team of engineers, physicists and chemists from Rice’s Laboratory for Nanophotonics (LANP) to make rice-shaped particles of gold and iron oxide.

"On the nanoscale, the shape of a particle plays a critical role in how it interacts with light," said LANP Director Naomi Halas. "We were looking for a new shape that would combine the best properties of the two most optically useful shapes – spheres and rods. It’s just a coincidence that that shape turned out to look exactly like a grain of rice."


Nanoparticles like nanorice can be used to focus light on small regions of space. Rice’s scientists plan to capitalize on this by attaching grains of nanorice to scanning probe microscopes. By moving the grains next to proteins and unmapped features on the surfaces of cells, they hope to get a far clearer picture than what’s available with current technology.

The nanorice research will appear in the April 12 issue of Nano Letters. Halas will discuss the findings at 11:30 a.m. today at a press conference at the American Physical Society’s 2006 March Meeting in room 334 of the Baltimore Convention Center.

In form, nanorice is similar to nanoshells, a spherical nanoparticle Halas invented in 1998 that is currently being examined for possible applications in molecular imaging, cancer treatment, medical diagnostics and chemical sensing. Both nanorice and nanoshells are made of a non-conducting core that is covered by a metallic shell.

Halas’ investigations find that nanorice possesses far greater structural tunability than nanoshells and another commonly studied optical nanoparticle, the nanorod. In fact, tests indicate that nanorice is the most sensitive surface plasmon resonance (SPR) nanosensor yet devised.

Research over the past decade has shown that nanoscale objects can amplify and focus light in ways scientists never imagined. The "how" of this involves plasmons, ripples of waves in the ocean of electrons that flow constantly across the surfaces of metals. When light of a specific frequency strikes a plasmon that oscillates at a compatible frequency, the energy from the light is converted into electrical energy that propagates, as plasmons, through the nanostructure.

Changing the shape of a metal at the nanoscale allows engineers and scientists to modify the properties of these plasmon waves, controlling the way that the metal nanostructure responds to light. Because of this, metal nanostructures can have beautiful, vivid colors that depend on their shape. Some nanoscale structures -- like nanorice and nanoshells -- act as superlenses that can amplify light waves and focus them to spot sizes far smaller than a wavelength of light.

In January 2005, for example, Halas and colleagues showed that nanoshells were about 10,000 times more effective at Surface-enhanced Raman Scattering (SERS) than traditional methods. Raman scattering is a type of spectrographic technique used by medical researchers, drug designers, chemists and others to determine the precise chemical makeup of materials.

"Plasmon resonance ’hot spots’ formed at the junction between a pair of nanoparticles- called dimers- provide higher SERS intensity than single nanoshells," said co-author Peter Nordlander, professor of physics and astronomy and of electrical and computer engineering. "Our computer models and experimental results show that the plasmon resonances of single grains of nanorice are on the same order of magnitude intensities as those obtained in junctions of nanoparticle dimers."

"The distinct advantage of the nanorice particle over nanoparticle dimers is that the electric field enhancements occur on open-ended surfaces of the particle that are much more accessible," said Halas, The Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry. "For SERS and SPR applications, we believe nanorice may have the field intensities needed to characterize biomolecules -- like proteins and DNA --that adsorb on the particle."

The nanorice core is made of non-conducting iron oxide and the outer covering of gold. The nanorice particles described in the Nano Letters paper were about 360 nanometers long and about 80 nanometers in diameter.

Phil Schewe | EurekAlert!
Further information:
http://www.rice.edu
http://www.aip.org

More articles from Physics and Astronomy:

nachricht Meteoritic stardust unlocks timing of supernova dust formation
19.01.2018 | Carnegie Institution for Science

nachricht Artificial agent designs quantum experiments
19.01.2018 | Universität Innsbruck

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>