Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

New filters could enable manufacturers to perform highly-selective chemical separation January 23rd, 2018

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Nanomedicine

Arrowhead Pharmaceuticals Announces Pricing of Underwritten Public Offering of Common Stock January 18th, 2018

Leti to Demo New Curving Technology at Photonics West that Improves Performance of Optical Components January 18th, 2018

Ultra-thin optical fibers offer new way to 3-D print microstructures: Novel approach lays groundwork for using 3-D printing to repair tissue in the body January 17th, 2018

Arrowhead Pharmaceuticals Announces Proposed Underwritten Offering of Common Stock January 17th, 2018

Discoveries

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

Announcements

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

New filters could enable manufacturers to perform highly-selective chemical separation January 23rd, 2018

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Industrial

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

New filters could enable manufacturers to perform highly-selective chemical separation January 23rd, 2018

STMicroelectronics Selects GLOBALFOUNDRIES 22FDX to Extend Its FD-SOI Platform and Technology Leadership : GFs FDX technology will enable ST to deliver high-performance, low-power products for next-generation consumer and industrial applications January 9th, 2018

A new product to help combat mouldy walls, thanks to technology developed at the ICN2 December 14th, 2017

Photonics/Optics/Lasers

Researchers use sound waves to advance optical communication January 22nd, 2018

New Method Uses DNA, Nanoparticles and Top-Down Lithography to Make Optically Active Structures: Technique could lead to new classes of materials that can bend light, such as for those used in cloaking devices January 18th, 2018

Leti to Demo New Curving Technology at Photonics West that Improves Performance of Optical Components January 18th, 2018

New exotic phenomena seen in photonic crystals: Researchers observe, for the first time, topological effects unique to an open system January 12th, 2018

Research partnerships

Ultra-thin memory storage device paves way for more powerful computing January 17th, 2018

New catalyst for hydrogen production is a step toward clean fuel: Carbon-based nanocomposite with embedded metal ions yields impressive performance as catalyst for electrolysis of water to generate hydrogen January 16th, 2018

New era in high field superconducting magnets opening new frontiers in science, nanotechnology and materials discovery January 9th, 2018

Touchy nanotubes work better when clean: Rice, Swansea scientists show that decontaminating nanotubes can simplify nanoscale devices January 4th, 2018

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