Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Nanoparticles reach new peaks: Rice University researchers show short laser pulses selectively heat gold nanoparticles

Rice University researchers found that pulsed (or "nonstationary") lasers could narrow the response spectra of 60-nanometer-wide gold nanoshells to a very narrow spectral band (red peak), as opposed to continuous ("stationary") excitation by laser (green peak). The discovery opens new possibilities for the use of metallic nanoparticles in medical and electronic applications.

Credit: Lapotko Group/Rice University
Rice University researchers found that pulsed (or "nonstationary") lasers could narrow the response spectra of 60-nanometer-wide gold nanoshells to a very narrow spectral band (red peak), as opposed to continuous ("stationary") excitation by laser (green peak). The discovery opens new possibilities for the use of metallic nanoparticles in medical and electronic applications.

Credit: Lapotko Group/Rice University

Abstract:
Plasmonic gold nanoparticles make pinpoint heating on demand possible. Now Rice University researchers have found a way to selectively heat diverse nanoparticles that could advance their use in medicine and industry.

Nanoparticles reach new peaks: Rice University researchers show short laser pulses selectively heat gold nanoparticles

Houston, TX | Posted on January 3rd, 2013

Rice scientists led by Dmitri Lapotko and Ekaterina Lukianova-Hleb showed common gold nanoparticles, known since the 19th century as gold colloids, heat up at near-infrared wavelengths as narrow as a few nanometers when hit by very short pulses of laser light. The surprising effect reported in Advanced Materials appears to be related to nonstationary optical excitation of plasmonic nanoparticles. Plasmons are free electrons on the surface of metals that become excited by the input of energy, typically from light. Moving plasmons can transform optical energy into heat.

"The key idea with gold nanoparticles and plasmonics in general is to convert energy," Lapotko said. "There are two aspects to this: One is how efficiently you can convert energy, and here gold nanoparticles are world champions. Their optical absorbance is about a million times higher than any other molecules in nature.

"The second aspect is how precisely one can use laser radiation to make this photothermal conversion happen," he said. Particles traditionally respond to wide spectra of light, and not much of it is in the valuable near-infrared region. Near-infrared light is invisible to water and, more critically for biological applications, to tissue.

"This was the problem," Lapotko said. "All nanoparticles, beginning with solid gold colloids and moving to more sophisticated, engineered gold nanoshells, nanorods, cages and stars, have very wide spectra, typically about 100 nanometers, which means we were allowed to use only one type of nanoparticle at a time. If we tried to use different types, their spectra overlapped and we did not benefit from the high tunability of lasers."

The discovery allows controlled laser pulses to tune the absorbance spectrum of plain gold colloids, Lapotko said. "This novel approach is counter to the established paradigm that assumes optical properties of nanoparticles are pre-set during their fabrication and stay constant during their optical excitation," he said.

The Rice lab showed basic colloidal gold nanoparticles could be efficiently activated by a short laser pulse at 780 nanometers, with an 88-fold amplification of the photothermal effect seen with a continuous laser. The researchers repeated their experiment with nanoparticle clusters in water, in living cancer cells and in animals, with the same or better results: they showed spectral peaks two nanometers wide. Such narrow photothermal spectra had never been seen for metal nanoparticles, either singularly or in clusters.

The effect appears to depend on vapor nanobubbles that form when the particles heat liquid in their immediate environment. The nanobubbles grow and burst in an instant. "Instead of using the nanoparticle as a heat sink with a continuous, stationary laser, we're creating a transient, nonstationary situation in which the particle interacts with the incident laser in a totally different way," Lapotko said. He said the effect is repeatable and works with laser pulses shorter than 100 picoseconds.

Even better, an experiment with mixed nanorods and nanoshells found they responded to laser pulses with strong, distinct signals at wavelengths 10 nanometers apart. That means two or more types of nanoparticles in the same location can be selectively activated on demand.

"The nanoparticles we used were nothing fancy; they were used in the 19th century by Michael Faraday, and it was believed they could do nothing in the near-infrared," he said. "That was the major motivation for people to invent nanorods, nanoshells and the other shapes. Here, we prove these inexpensive particles can behave quite well in near-infrared." He said the discovery opens the possibility that many metal nanoparticles could be used in biomedical and industrial applications where spectral selectivity and tuning would provide "unprecedented" precision.

"This is still more a phenomenon rather than a firmly established mechanism, with a nice theoretical basis," Lapotko said. "But when fully clarified, it could become a universal tool."

Co-authors of the paper are Alexey Volkov, a research scientist at the University of Virginia, and Xiangwei Wu, an associate professor in the Department of Head and Neck Surgery at the University of Texas MD Anderson Cancer Center. Lapotko is a faculty fellow in biochemistry and cell biology, and Lukianova-Hleb is a research scientist at Rice.

The National Institutes of Health supported the research.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,708 undergraduates and 2,374 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 2 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to tinyurl.com/AboutRice.

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
Mike Williams

713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Read the abstract at:

The Plasmonic Nanobubble Lab at Rice:

Related News Press

News and information

The International Space Elevator Consortium (ISEC) is proud to announce the 2014 Space Elevator Conference! This annual event will be held at the Museum of Flight in Seattle, Washington from Friday, August 22nd through Sunday, August 24th August 19th, 2014

KaSAM-2014 International Conference (September 7-10, 2014, Kathmandu, Nepal) August 19th, 2014

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Nanomedicine

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

Interaction between Drug, DNA for Designing Anticancer Drugs Studied in Iran August 17th, 2014

Scientists fold RNA origami from a single strand: RNA origami is a new method for organizing molecules on the nanoscale. Using just a single strand of RNA, this technique can produce many complicated shapes. August 14th, 2014

Iranian Scientists Stabilize Protein on Highly Stable Electrode Surface August 14th, 2014

Discoveries

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Сalculations with Nanoscale Smart Particles August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

Announcements

Сalculations with Nanoscale Smart Particles August 19th, 2014

Life on Mars? Implications of a newly discovered mineral-rich structure August 19th, 2014

Harris & Harris Group Letter to Shareholders on Website August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Industrial

Iranians Find Novel Method for Processing Highly Pure Ceramic Nanoparticles August 12th, 2014

PerkinElmer to Display Innovative Detection and Informatics Offerings at ACS National Meeting & Exposition Detection, Data Visualization and Analytics for Chemistry Professionals August 8th, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Photonics/Optics/Lasers

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Laser makes microscopes way cooler: Cooling a nanowire probe with a laser could lead to substantial improvements in the sensitivity of atomic force probe microscopes August 15th, 2014

Molecular engineers record an electron's quantum behavior August 14th, 2014

Harry Atwater and Albert Polman receive the Julius Springer Prize for Applied Physics 2014: Scientists honored for their pioneering achievements in plasmonics and nanophotonics August 8th, 2014

Research partnerships

Сalculations with Nanoscale Smart Particles August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Nano Bonds Increase Raw Strength of Fireproof Concretes August 18th, 2014

Production of Toxic Ion Nanosorbents with High Sorption Capacity in Iran August 17th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE