Featured Research

from universities, journals, and other organizations

Nano imagining takes turn for the better: Photothermal technique provides new way to track nanoparticles

Date:
February 5, 2010
Source:
Rice University
Summary:
Scientists researching how nanomaterials align have found a way to use gold nanorods as orientation sensors by combining their plasmonic properties with polarization imaging techniques.

Scientists researching how nanomaterials align have found a way to use gold nanorods as orientation sensors by combining their plasmonic properties with polarization imaging techniques.
Credit: Image courtesy of Rice University

Stephan Link wants to understand how nanomaterials align, and his lab's latest work is a step in the right direction.

Link's Rice University group has found a way to use gold nanorods as orientation sensors by combining their plasmonic properties with polarization imaging techniques.

That may make it possible to see and perhaps track single nanoparticles over long periods. It would give researchers new information about materials, including living systems, that incorporate them.

"With a spherical particle, you don't have any information about how it's oriented," said Link, an assistant professor of chemistry and electrical and computer engineering at Rice. "We wanted to see if we could determine the orientation of the nanorods, and eventually we'd like to be able to measure the orientation of the environment they're in. We think this technique could be really useful for that."

Link, primary author Wei-Shun Chang, a Rice research scientist, and their collaborators reported their results in the online edition of the Proceedings of the National Academy of Sciences.

Seeing a single nanoparticle is nothing new. A scanning tunneling microscope (STM) can capture images of particles down to a few nanometers; particles tagged with fluorescent molecules can be seen for as long as the fluorophores are active. Link used this latter method to show nanocars rolling at room temperature last year.

But there are problems with each of those techniques. STMs see nanotubes or quantum dots just fine as long as they're more or less isolated on a conductive surface. But in the wild, the particles would get lost amid the clutter of everything else the microscope sees. And while fluorophores can help pick particles out of the crowd, they can deteriorate in as little as 30 seconds, which limits their usefulness.

Gold nanorods can be "lit up" at will. Lasers at particular wavelengths excite surface plasmons that absorb the energy and emit a heat signature that can be detected by a probe laser. Because plasmons are highly polarized along a nanorod's length, reading the signal while turning the polarization of the laser tells researchers precisely how the rod is oriented.

An electron microscope photo from the new paper shows nanorods about 75 nanometers long and 25 nanometers wide on a glass slide at 90-degree angles to each other. An adjacent photothermal image shows them as pixilated smudges. The smudges are strongest when the laser polarization aligns lengthwise with the nanorods, but they disappear when the laser polarization and rods are 90 degrees out of phase.

"With plasmonics, you always have two properties: absorption and scattering," Link said. "Depending on the size, one or the other dominates. What's unique is that it's now possible to do both on the same structure or do it individually -- so we can only measure absorption or only measure scattering."

Nanorods much smaller than 50 nanometers are not detectable by some scattering methods, Link said, but photothermal detection should work with metallic particles as small as five nanometers; this makes them useful for biological applications. "These gold nanorods are biocompatible. They are not toxic to cells," said Chang, noting their similarity to gold nanoshells currently in human cancer therapy trials based on research by Rice scientists Naomi Halas and Jennifer West.

"Our work is more geared to the fundamentals," Link said of the basic nature of his group's research. "Maybe we can optimize the conditions, and then a physician or somebody who's engineering a probe can take it from there.

"Our place is a little further down the chain of development. I'm happy with that."

Co-authors of the paper are Rice graduate students Ji Won Ha and Liane Slaughter. The Robert A. Welch Foundation and 3M supported the work.


Story Source:

The above story is based on materials provided by Rice University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Wei-Shun Chang, Ji Won Ha, Liane S. Slaughter, and Stephan Link. Plasmonic nanorod absorbers as orientation sensors. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.0910127107

Cite This Page:

Rice University. "Nano imagining takes turn for the better: Photothermal technique provides new way to track nanoparticles." ScienceDaily. ScienceDaily, 5 February 2010. <www.sciencedaily.com/releases/2010/02/100203161430.htm>.
Rice University. (2010, February 5). Nano imagining takes turn for the better: Photothermal technique provides new way to track nanoparticles. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2010/02/100203161430.htm
Rice University. "Nano imagining takes turn for the better: Photothermal technique provides new way to track nanoparticles." ScienceDaily. www.sciencedaily.com/releases/2010/02/100203161430.htm (accessed August 21, 2014).

Share This




More Matter & Energy News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com
Researcher Testing on-Field Concussion Scanners

Researcher Testing on-Field Concussion Scanners

AP (Aug. 19, 2014) Four Texas high school football programs are trying out an experimental system designed to diagnose concussions on the field. The technology is in response to growing concern over head trauma in America's most watched sport. (Aug. 19) Video provided by AP
Powered by NewsLook.com
Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

AFP (Aug. 19, 2014) A solar cell that resembles a flower is offering a new take on green energy in Japan, where one scientist is searching for renewables that look good. Duration: 01:29 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins