Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > New structural information on functionalization of gold nanoparticles

Visualization of the atomic structure of the Au102(p-MBA)44 particle (left) and the partially ligand-exchanged Au102(p-MBA)40(p-BBT)4 (right). The exchanged ligand bromo benzene thiol (p-BBT) is schematically shown in the middle and the observed ligand exchange sites by red and blue on the right.
Visualization of the atomic structure of the Au102(p-MBA)44 particle (left) and the partially ligand-exchanged Au102(p-MBA)40(p-BBT)4 (right). The exchanged ligand bromo benzene thiol (p-BBT) is schematically shown in the middle and the observed ligand exchange sites by red and blue on the right.

Abstract:
Nanometre-scale gold particles are currently intensively investigated for possible applications as catalysts, sensors, biolabels, drug delivery devices, biological contrast agents and as components in photonics and molecular electronics. The particles are prepared in a solution from gold salts and their reactive gold cores can be stabilized with various organic ligands. Particularly stable particles can be synthesized by using organothiol ligands that have a strong chemical interaction to gold, producing precise compositions in the size range of 1 to 3 nanometres. Modification of the protecting molecular overlayer is a key step in almost all applications. A detailed structural atomistic understanding of the processes of the exchange reaction has been lacking.

New structural information on functionalization of gold nanoparticles

Helsinki, Finland | Posted on August 2nd, 2012

Now, professors Chris Ackerson in the Colorado State University in Ft. Collins, USA, and Hannu Häkkinen at the Nanoscience Center of the University of Jyväskylä, Finland, report the first structural study on the atomistic processes of a ligand-exchange reaction of a well-defined gold nanoparticle that has 102 gold atoms and 44 ligand sites in the molecular overlayer. The study was published in the Journal of the American Chemical Society on 21 July 2012 [1]. Prof. Häkkinen's work is funded by the Academy of Finland and prof. Ackerson's work is funded by the Colorado State University and the American Federation for Aging Research.

The studied particle has a chemical formula of Au102(p-MBA)44 and it was made by using a water-soluble thiol (para - mercapto benzoic acid, p-MBA) as the stabilizing molecule. The X-ray crystal structure of this particle was first reported as the cover article of Science in 2007 by the group of Roger D. Kornberg from Stanford University [2]. Häkkinen led an international team of researchers that published a theoretical analysis of this and other thiol-stabilized gold nanoparticles in 2008 in the Proceedings of the National Academy of Sciences [3].

In the new study, Ackerson's group succeeded in making heterogeneous crystals of samples of Au102 particles that had undergone a ligand-exchange reaction where the p-MBA thiols in the molecular overlayer had been partially exchanged to a similar thiol containing a Bromine atom, the so-called para - bromo benzene thiol (p-BBT), under a fast 5-minute reaction.

The analysis of the heterogeneous crystals showed which ligand sites in the overlayer are the most likely to be changed during the short reaction time, i.e., from which sites the exchange process starts. Surprisingly, only 4 sites out of the 44 possibilities showed occupation by the exchanged ligand (see Figure). Theoretical analysis performed by Häkkinen's group gave insight into the atomistic details of possible reaction mechanisms. Evidence from experiment and theory indicates that the Au102(p-MBA)44 nanoparticle has a thiol overlayer where almost every thiol ligand site has its own reaction rate due to a highly heterogeneous structure of the overlayer. "The Au102(p-MBA)44 nanoparticle has a structure reminiscent of a protein, with a rigid inorganic gold core analogous to the alpha-carbon backbone of a protein core and chemically modifiable functional groups in the low-symmetry molecular overlayer", says prof. Ackerson. "When ligand exchange reactions are better understood, we hope to fully control the surface functionalization of the Au102 and similar water-soluble gold nanoparticles. The implications in biology for a fully controllable synthetic surface the size of a protein are profound", says prof. Häkkinen.

The other researchers involved in the work are Christine Heinecke, Thomas Ni and Andrea Wong from Ft. Collins and Sami Malola and Ville Mäkinen from Jyväskylä. The massively parallel computations needed for interpretation of the experimental observations were made in the Louhi supercomputer at CSC - the Finnish IT Center for Science in Espoo.

Full bibliographic informationThe study was published in the Journal of the American Chemical Society on 21 July 2012 [1].

1. C.L. Heinecke, T.W. Ni, S.A. Malola, V.P. Mäkinen, O.A. Wong, H. Häkkinen and C.J. Ackerson, "Structural and theoretical basis for ligand exchange on thiolate monolayer protected gold nanoclusters", J. Am. Chem. Soc., published online July 21, 2012 (http://pubs.acs.org/doi/abs/10.1021/ja3032339).

2. P.D. Jadzinsky, G. Calero, C.J. Ackerson, D.A. Bushnell and R.D. Kornberg, "Structure of a thiol monolayer-protected gold nanoparticle at 1.1. Ångstrom resolution", Science 318, 430 (2007) (http://www.sciencemag.org/content/318/5849/430.abstract).

3. M. Walter, J. Akola, O. Lopez-Acevedo, P. D. Jadzinsky, G. Calero, C. J. Ackerson, R. L. Whetten, H. Grönbeck, H. Häkkinen, "A unified view of ligand-protected gold clusters as superatom complexes", Proc. Natl. Acad. Sci. (USA) 105, 9157 (2008) (http://www.pnas.org/content/105/27/9157). See also http://gtresearchnews.gatech.edu/newsrelease/gold-nanoclusters.htm.

####

For more information, please click here

Contacts:
Anita Westerback
+358 (0) 9 7748 8306


Professor Chris Ackerson
Colorado State University
tel. +1 970 491 0521


Professor Hannu Häkkinen
University of Jyväskylä
tel. +358 400 247 973


Academy of Finland Communications
Communications Specialist
Leena Vähäkylä
tel. +358 9 7748 8327

Copyright © AlphaGalileo

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

Chemistry

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

News and information

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Nanomedicine

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Researchers develop artificial building blocks of life March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Materials/Metamaterials/Magnetoresistance

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project