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 NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>