Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

News and information

Geoffrey Beach: Drawn to explore magnetism: Materials researcher is working on the magnetic memory of the future April 25th, 2017

Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light April 25th, 2017

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Chemistry

Shedding light on the absorption of light by titanium dioxide April 14th, 2017

Researchers uncover secret of nanomaterial that makes harvesting sunlight easier March 29th, 2017

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Researchers develop groundbreaking process for creating ultra-selective separation membranes: Discovery could greatly improve energy-efficiency of separation and purification processes in the chemical and petrochemical industries March 15th, 2017

Nanomedicine

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Arrowhead Presents ARC-520 and ARC-521 Clinical Data at The International Liver Congress(TM) April 20th, 2017

Nano-SPEARs gently measure electrical signals in small animals: Rice University's tiny needles simplify data gathering to probe diseases, test drugs April 17th, 2017

Nanotubes that build themselves April 14th, 2017

Discoveries

Geoffrey Beach: Drawn to explore magnetism: Materials researcher is working on the magnetic memory of the future April 25th, 2017

Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light April 25th, 2017

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Materials/Metamaterials

Geoffrey Beach: Drawn to explore magnetism: Materials researcher is working on the magnetic memory of the future April 25th, 2017

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Russian scientists create new system of concrete building structures: Sientists of Peter the Great Saint-Petersburg Polytechnic University developed a new construction technology April 24th, 2017

Two-dimensional melting of hard spheres experimentally unravelled after 60 years: First definitive experimental evidence of two-dimensional melting of hard spheres April 21st, 2017

Announcements

Geoffrey Beach: Drawn to explore magnetism: Materials researcher is working on the magnetic memory of the future April 25th, 2017

Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light April 25th, 2017

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

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