Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Precious metal gets picky

Abstract:
Gold nanoparticles adhere to only certain faces of crystals of the amino acid cystine

Precious metal gets picky

Posted on July 14, 2006

Not only jewelry-loving ladies but also scientists and technologists are fascinated by gold–particularly in the form of the smallest clumps imaginable. Gold nanoparticles stand out through their unique optical, electronic, and catalytic properties and are the ideal "building blocks" for nanostructures. Composite materials with a one or two-dimensional arrangement of the gold nanoparticles are especially interesting for the construction of components on the nanoscale.

Japanese scientists have now shown that crystals of organic compounds are the ideal partner for such gold composite materials. Gold nanoparticles do not colonize all the surfaces of the organic crystal evenly, they are choosy, and occupy only certain faces. The researchers working with Seiji Shinkai and Kazuki Sada employ millimeter-sized single crystals of the amino acid L-cystine. A single crystal is composed of a single, uniform crystal lattice. Cystine crystallizes in the form of hexagonal prisms. Such a crystal has two parallel hexagonal surfaces the edges of which are linked together by six rectangular faces. If the transparent crystal is immersed for two hours in a solution of gold nanoparticles it becomes purple. Under the microscope it can be seen that only the two hexagonal faces are purple. The sides, that is, the rectangular faces remain colorless. The purple coloration arises from deposited gold nanoparticles. Clearly the tiny gold particles are choosy and populate exclusively the hexagonal faces of the prism.

Why? The cystine molecules are arranged in layers in the crystal, these layers are parallel to the hexagonal faces. The layers are held together by a two-dimensional network of hydrogen bonds that run between the amino and the acid groups of the amino acid. These polar groups lie on the surface of the two hexagonal faces and attract the gold particles by electrostatic interactions. The rectangular faces, however, are made up of alternating layers of polar and nonpolar groups. The density of attractive polar groups here is too low to draw the gold particles onto these faces.

The face-selective coverage also works with microscale crystals. The gold coating could be used, for example, to selectively bind other materials. Through the attractive and repulsive forces between coated and uncoated faces of the crystals it should be possible to make the crystals stack in a direction-dependent manner and so form defined aggregate structures in a targeted fashion.

####


Author: Kazuki Sada, Kyushu University, Fukuoka (Japan), www.cstm.kyushu-u.ac.jp/shinkai/101/sada_H.htm

Title: Anisotropic Decoration of Gold Nanoparticles onto Specific Crystal Faces of Organic Single Crystals

Angewandte Chemie International Edition, 2006, 45, No. 29, 4764–4767, doi: 10.1002/anie.200601470

Contact:
Editorial office:
angewandte@wiley-vch.de

or David Greenberg (US)
dgreenbe@wiley.com

or Julia Lampam (UK)
jlampam@wiley.co.uk

Copyright © Angewandte Chemie

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

Possible Futures

Animal study shows flexible, dissolvable silicon device promising for brain monitoring: Other applications include post-operative observation for vascular, cardiac, and orthopaedic procedures, finds Penn study May 5th, 2016

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Clues on the path to a new lithium battery technology: Charging produces highly reactive singlet oxygen in lithium air batteries May 5th, 2016

Materials/Metamaterials

A View Through Wood Shows Futuristic Applications: Transparent wood made at UMD could create new windows, cars and solar panels May 5th, 2016

Clay nanotube-biopolymer composite scaffolds for tissue engineering May 1st, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Hybrid nanoantennas -- next-generation platform for ultradense data recording April 28th, 2016

Announcements

Speedy ion conduction in solid electrolytes clears road for advanced energy devices May 5th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 2016

Clues on the path to a new lithium battery technology: Charging produces highly reactive singlet oxygen in lithium air batteries May 5th, 2016

Unique nano-capsules promise the targeted drug delivery: Russian scientists created unique nano-capsules for the targeted drug delivery May 5th, 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







Car Brands
Buy website traffic