Nanotechnology Now

Our NanoNews Digest Sponsors







Heifer International

Wikipedia Affiliate Button


Home > Press > Press Release: Carnegie Mellon Researchers Use NMR to Determine Whether Gold Nanoparticles Exhibit "Handedness"

Pictured above is the crystal structure of a pair of gold nanoparticles that exist in a right-handed (bottom) and left-handed (top) configuration. These nanoparticles hold great promise as a chiral catalyst—a tool highly sought-after by the pharmaceutical industry.
Pictured above is the crystal structure of a pair of gold nanoparticles that exist in a right-handed (bottom) and left-handed (top) configuration. These nanoparticles hold great promise as a chiral catalyst—a tool highly sought-after by the pharmaceutical industry.

Abstract:
Carnegie Mellon University's Roberto R. Gil and Rongchao Jin have successfully used NMR to analyze the structure of infinitesimal gold nanoparticles, which could advance the development and use of the tiny particles in drug development.

Press Release: Carnegie Mellon Researchers Use NMR to Determine Whether Gold Nanoparticles Exhibit "Handedness"

Pittsburgh, PA | Posted on December 8th, 2011

Their approach offers a significant advantage over routine methods for analyzing gold nanoparticles because it can determine whether the nanoparticles exist in a both right-handed and left-handed configuration, a phenomenon called chirality. Determining a nanoparticle's chirality is an important step toward developing them as chiral catalysts — tools that are highly sought-after by the pharmaceutical industry. Their results are published online at ACS Nano.

Many drugs on the market today contain at least one molecule that is chiral. Often only one of the configurations, or isomers, is effective in the body. In some cases, the other isomer may even be harmful. A striking example is the drug thalidomide, which consisted of two isomers: one of which helped pregnant women control nausea while the other caused damage to the developing fetus. In an effort to create safer, more effective drugs, drug manufacturers are looking for ways to produce purer substances that contain only the left- or right-handed isomer.

Huifeng Qian, a fourth-year graduate student working with Jin, created a gold nanoparticle that has the potential to catalyze chemical reactions that will produce one isomer rather than the other. The nanoparticle is comprised of precisely 38 gold atoms and measures a mere 1.4 nanometers. Qian worked diligently for nearly a year to grow the nanoparticles into high-quality crystals so that he could study their structure using x-ray crystallography.

"Growing a pure crystal from nanoparticles is very challenging, and you may not even be able to get a crystal at all," said Jin, an assistant professor of chemistry in CMU's Mellon College of Science. "In the nanoparticle community, the crystal structures of only three nanoparticles have been reported."

In Jin's case, x-ray crystallography revealed that the gold nanoparticle is chiral. Chemists typically probe the internal chiral structure of gold nanoparticles using a technique called circular dichoism spectroscopy. When pure chiral molecules are exposed to circularly polarized light, each isomer absorbs the light differently, resulting in a unique — and of opposite sign — spectrum for each isomer. The process of creating the gold nanoparticles, however, often results in a 50/50 mix of each isomer, known as racemates.

"Because the spectrum is of opposite sign for each isomer, they cancel each other out and the net optical response is zero. This makes circular dichoism (CD) spectroscopy useless when it comes to determining the chirality of gold nanoparticles in 50/50 mixtures," said Gil, associate research professor of chemistry and director of the Department of Chemistry's NMR Facility.

Since Jin couldn't use circular dichoism spectroscopy, Gil was able to use NMR to help Jin distinguish between his gold nanoparticles' left- and right-handed isomers.

NMR spectroscopy takes advantage of the physical phenomenon wherein some nuclei wobble and spin like tops, emitting and absorbing a radio frequency signal in a magnetic field. By observing the behavior of these spinning nuclei, scientists can piece together the chemical structure of the compound.

In 1957, scientists observed that the hydrogen atoms of a freely rotating methylene (CH2) group produced two different frequencies if they were close to a chiral center. Jin's gold nanoparticles, which have a chiral core, are cushioned by several chemical groups, including freely rotating methylene groups. Gil reasoned that the nanoparticles' chiral core should induce the methylene group's two hydrogen atoms to give off different frequencies, a phenomenon known as diastereotopicity.

Gil and Jin compared the NMR signal from the hydrogen atoms in a non-chiral gold nanoparticle with the NMR signal from the hydrogen atoms in chiral gold nanoparticle. The non-chiral nanoparticle's NMR spectrum did not reveal any differences, but the chiral nanoparticle's NMR spectrum revealed two different hydrogen signals, providing a simple and efficient way of telling whether the particle is chiral or not, even for a 50/50 mixture of isomers.

"NMR is an alternative — and very efficient — method for providing useful information about how the atoms in nanoparticles form the molecular structure. Because NMR can determine chirality in some cases, it can readily be used to determine the purity of a nanoparticle mixture," Jin said.

In current work, Jin and Qian are striving to turn their 50/50 mixture of right- and left-handed isomers into a pure solution of one or the other.

####

For more information, please click here

Contacts:
Jocelyn Duffy
412-268-9982

Copyright © Carnegie Mellon 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 News Press

News and information

Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013

Bacterial spare parts filter antibiotic residue from groundwater May 22nd, 2013

UofL scientists uncover how grapefruits provide a secret weapon in medical drug delivery May 22nd, 2013

Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013

Chemistry

Study Led by George Washington University Professor Provides Better Understanding of Water’s Freezing Behavior at Nanoscale May 21st, 2013

Penn engineers' nanoantennas improve infrared sensing May 20th, 2013

Iranian Scientists Use Pomegranate Juice to Produce Copper Iodide Nanostructure May 14th, 2013

Chemistry breakthrough sheds new light on illness and health May 12th, 2013

Nanomedicine

UofL scientists uncover how grapefruits provide a secret weapon in medical drug delivery May 22nd, 2013

Single-Cell Transfection Tool Enables Added Control for Biological Studies: McCormick researchers develop method of delivering molecules into targeted cells May 22nd, 2013

How Gold Nanoparticles Can Help Fight Ovarian Cancer May 21st, 2013

MU Researchers Develop Radioactive Nanoparticles that Target Cancer Cells: This is an early step toward developing therapies for metastasized cancers, MU scientist says May 21st, 2013

Discoveries

Weird science: Crystals melt when they're cooled May 22nd, 2013

Innovation could bring flexible solar cells, transistors, displays May 22nd, 2013

Researchers Stitch Defects into the World’s Thinnest Semiconductor May 22nd, 2013

Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013

Materials

Weird science: Crystals melt when they're cooled May 22nd, 2013

INSCX™ exchange announces substantial increase in capital designated to provide Trade Finance for registered Nanomaterial Producers May 21st, 2013

International survey supports need for built-in water protection on smartphones and tablets May 21st, 2013

Kinks and curves at the nanoscale: New research shows 'perfect twin boundaries' are not so perfect May 20th, 2013

Announcements

Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013

Bacterial spare parts filter antibiotic residue from groundwater May 22nd, 2013

UofL scientists uncover how grapefruits provide a secret weapon in medical drug delivery May 22nd, 2013

Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency: MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities May 22nd, 2013

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








abbigliamento uomo
Computer Accessories
© Copyright 1999-2013 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE