Featured Research

from universities, journals, and other organizations

Nanoscopic Golden Rods

Date:
September 12, 2008
Source:
Wiley-Blackwell
Summary:
Scientists have now developed a new method for the production of nanoscopic gold rods. In contrast to previous methods, they have achieved this without the use of cytotoxic additives, using an ionic liquid as a solvent.

Scientists have developed a new method for the production of nanoscopic gold rods.
Credit: Copyright Wiley-VCH

Gold nanoparticles are under consideration for a number of biomedical applications, such as tumor treatment. A German-American research team at Carnegie Mellon University in Pittsburgh, Hunter College in New York, and the RWTH Aachen has now developed a new method for the production of nanoscopic gold rods.

Related Articles


In contrast to previous methods, they have achieved this without the use of cytotoxic additives. As they report in the journal Angewandte Chemie, the synthesis is not carried out in water, but in an ionic liquid, a “liquid salt”.

Cancer cells are relatively temperature-sensitive. This is exploited in treatments involving overheating of parts of the cancer patient’s body. One highly promising method is photoinduced hyperthermia, in which light energy is converted to heat.

Gold nanoparticles absorb light very strongly in the near infrared, a spectral region that is barely absorbed by tissue. The absorbed light energy causes the gold particles to vibrate and is dissipated into the surrounding area as heat. The tiny gold particles can be functionalized so that the specifically bind to tumor cells. Thus, only cells that contain gold particles are killed off.

The problem? Ordinary spherical gold particles do not efficiently convert the light energy into heat; only rod-shaped particles will do. Unfortunately, the additives needed to crystallize the rod-shaped particles from aqueous solutions are cytotoxic.

The team headed by Michael R. Bockstaller is now pursuing a new strategy: instead of aqueous solution, they chose to use an ionic liquid as their medium of crystallization. Ionic liquids are “liquid salts”, organic compounds that exist as oppositely charged ions, but in the liquid state. In this way, the researchers have been able to produce gold nanorods without the use of any cytotoxic additives.

In the first step, seed crystals are produced in the form of tiny spherical gold particles. These crystals are added to a “secondary growth solution” containing monovalent gold ions, silver ions, and the weak reducing agent ascorbic acid. The solvent is an imidazolium-based ionic liquid. In this medium, the crystals don’t continue to grow into spheres; instead they form rods with the round crystallization nuclei as “heads”.

The mechanism is presumed to involve the various, energetically inequivalent surfaces of the crystal lattice: the aromatic, nitrogen-containing five-membered rings of the ionic liquid prefer to accumulate at the highly energetic facets of gold surfaces. They thus stabilize crystal shapes that have fewer low-energy facets than the normal spherical equilibrium form. This results in long rods.


Story Source:

The above story is based on materials provided by Wiley-Blackwell. Note: Materials may be edited for content and length.


Journal Reference:

  1. Ryu et al. Imidazolium-Based Ionic Liquids as Efficient Shape-Regulating Solvents for the Synthesis of Gold Nanorods. Angewandte Chemie International Edition, 2008; NA DOI: 10.1002/anie.200802185

Cite This Page:

Wiley-Blackwell. "Nanoscopic Golden Rods." ScienceDaily. ScienceDaily, 12 September 2008. <www.sciencedaily.com/releases/2008/09/080908101624.htm>.
Wiley-Blackwell. (2008, September 12). Nanoscopic Golden Rods. ScienceDaily. Retrieved November 21, 2014 from www.sciencedaily.com/releases/2008/09/080908101624.htm
Wiley-Blackwell. "Nanoscopic Golden Rods." ScienceDaily. www.sciencedaily.com/releases/2008/09/080908101624.htm (accessed November 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, November 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
NSA Director: China Can Damage US Power Grid

NSA Director: China Can Damage US Power Grid

AP (Nov. 20, 2014) China and "one or two" other countries are capable of mounting cyberattacks that would shut down the electric grid and other critical systems in parts of the United States, according to Adm. Michael Rogers, director of the National Security Agency and hea Video provided by AP
Powered by NewsLook.com
Latest Minivan Crash Tests Aren't Pretty

Latest Minivan Crash Tests Aren't Pretty

Newsy (Nov. 20, 2014) Five minivans were put to the test in head-on crash simulations by the Insurance Institute for Highway Safety. Video provided by Newsy
Powered by NewsLook.com
Takata Offers "sincerest Condolences" To Victims of Malfunctioning Airbag

Takata Offers "sincerest Condolences" To Victims of Malfunctioning Airbag

Reuters - US Online Video (Nov. 20, 2014) U.S. Congress hears from a victim and company officials as it holds a hearing on the safety of Takata airbags after reports of injuries. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins