Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Improved characterization of nanoparticle clusters for EHS and biosensors research

Clusters of roughly 30-nanometer gold nanoparticles imaged by transmission electron microscopy. (Color added for clarity.)

Credit: Keene, FDA
Clusters of roughly 30-nanometer gold nanoparticles imaged by transmission electron microscopy. (Color added for clarity.)

Credit: Keene, FDA

Abstract:
The tendency of nanoparticles to clump together in solution—"agglomeration"—is of great interest because the size of the clusters plays an important role in the behavior of the materials. Toxicity, the persistence of the nanomaterials in the environment, their efficacy as biosensors and, for that matter, the accuracy of experiments to measure these factors, are all known to be affected by agglomeration and cluster size. Recent work* at the National Institute of Standards and Technology (NIST) offers a way to measure accurately both the distribution of cluster sizes in a sample and the characteristic light absorption for each size. The latter is important for the application of nanoparticles in biosensors.

Improved characterization of nanoparticle clusters for EHS and biosensors research

Gaithersburg, MD | Posted on October 26th, 2011

A good example of the potential application of the work, says NIST biomedical engineer Justin Zook, is in the development of nanoparticle biosensors for ultrasensitive pregnancy tests. Gold nanoparticles can be coated with antibodies to a hormone** produced by an embryo shortly after conception. Multiple gold nanoparticles can bind to each hormone, forming clusters that have a different color from unclustered gold nanoparticles. But only certain size clusters are optimal for this measurement, so knowing how light absorbance changes with cluster size makes it easier to design the biosensors to result in just the right sized clusters.

The NIST team first prepared samples of gold nanoparticles—a nanomaterial widely used in biology—in a standard cell culture solution, using their previously developed technique for creating samples with a controlled distribution of sizes***. The particles are allowed to agglomerate in gradually growing clusters and the clumping process is "turned off" after varying lengths of time by adding a stabilizing agent that prevents further agglomeration.

They then used a technique called analytical ultracentrifugation (AUC) to simultaneously sort the clusters by size and measure their light absorption. The centrifuge causes the nanoparticle clusters to separate by size, the smaller, lighter clusters moving more slowly than the larger ones. While this is happening, the sample containers are repeatedly scanned with light and the amount of light passing through the sample for each color or frequency is recorded. The larger the cluster, the more light is absorbed by lower frequencies. Measuring the absorption by frequency across the sample containers allows the researchers both to watch the gradual separation of cluster sizes and to correlate absorbed frequencies with specific cluster sizes.

Most previous measurements of absorption spectra for solutions of nanoparticles were able only to measure the bulk spectra—the absorption of all the different cluster sizes mixed together. AUC makes it possible to measure the quantity and distribution of each nanoparticle cluster without being confounded by other components in complex biological mixtures, such as proteins. The technique previously had been used only to make these measurements for single nanoparticles in solution. The NIST researchers are the first to show that the procedure also works for nanoparticle clusters.

* J.M. Zook, V. Rastogi, R.I. MacCuspie, A.M. Keene and J. Fagan. Measuring agglomerate size distribution and dependence of localized surface plasmon resonance absorbance on gold nanoparticle agglomerate size using analytical ultracentrifugation. ACS Nano, Articles ASAP (As Soon As Publishable). Publication Date (Web): Sept. 3, 2011 DOI: 10.1021/nn202645b.

** HCG: Human chorionic gonadotropin.

*** See J.M. Zook, R.I. MacCuspie, L.E. Locascio, M.D. Halter and J.T. Elliott. Stable nanoparticle aggregates/agglomerates of different sizes and the effect of their size on hemolytic cytotoxicity. Nanotoxicology, published online Dec. 13, 2010 (DOI: 10.3109/17435390.2010.536615) and the Feb. 2, 2011, NIST Tech Beat article, "NIST Technique Controls Sizes of Nanoparticle Clusters for EHS Studies," at www.nist.gov/public_affairs/tech-beat/tb20110202.cfm#nanoparticles.

####

For more information, please click here

Contacts:
Michael E. Newman

301-975-3025

Copyright © National Institute of Standards and Technology (NIST)

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 News Press

News and information

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Laboratories

Nanoscale view of energy storage January 16th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Nanoscale view of energy storage January 16th, 2017

Chemistry on the edge: Experiments at Berkeley Lab confirm that structural defects at the periphery are key in catalyst function January 13th, 2017

Recreating conditions inside stars with compact lasers: Scientists offer a new path to creating the extreme conditions found in stars, using ultra-short laser pulses irradiating nanowires January 12th, 2017

Deciphering the beetle exoskeleton with nanomechanics: Understanding exoskeletons could lead to new, improved artificial materials January 12th, 2017

Sensors

Nanoscale Modifications can be used to Engineer Electrical Contacts for Nanodevices January 13th, 2017

Researchers create practical and versatile microscopic optomechanical device: Trapping light and mechanical waves within a tiny bullseye, design could enable more sensitive motion detection January 11th, 2017

STMicroelectronics Peps Up Booming Social-Fitness Scene with Smart Motion Sensors for Better Accuracy, Longer Battery Life, and Faster Time to Market January 2nd, 2017

Advance in intense pulsed light sintering opens door to improved electronics manufacturing December 23rd, 2016

Discoveries

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

Announcements

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

Environment

Investigating the impact of natural and manmade nanomaterials on living things: Center for Environmental Implications of Nanotechnology develops tools to assess current and future risk January 9th, 2017

PCATDES Starts Field Testing of Photocatalytic Reactors in South East Asia December 28th, 2016

Advance in intense pulsed light sintering opens door to improved electronics manufacturing December 23rd, 2016

Carbon dots dash toward 'green' recycling role: Rice scientists, colleagues use doped graphene quantum dots to reduce carbon dioxide to fuel December 18th, 2016

Safety-Nanoparticles/Risk management

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Investigating the impact of natural and manmade nanomaterials on living things: Center for Environmental Implications of Nanotechnology develops tools to assess current and future risk January 9th, 2017

First time physicists observed and quantified tiny nanoparticle crossing lipid membrane November 7th, 2016

SUN shares its latest achievements during the 3rd Annual Project Meeting November 1st, 2016

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