Featured Research

from universities, journals, and other organizations

Low Cost Quantum Dots For Biological Research Produced Through Microwave Synthesis

Date:
June 19, 2008
Source:
National Institute of Standards and Technology
Summary:
Materials researchers have developed a simplified, low-cost process for producing high-quality, water-soluble 'quantum dots' for biological research.

Brightly glowing vials of highly luminescent, water soluble quantum dots produced by the new NIST microwave process span a wavelength range from 500 to 600 nm.
Credit: NIST

Materials researchers at the National Institute of Standards and Technology (NIST) have developed a simplified, low-cost process for producing high-quality, water-soluble "quantum dots" for biological research. By using a laboratory microwave reactor to promote the synthesis of the widely used nanomaterials, the recently published NIST process avoids a problematic step in the conventional approach to making quantum dots, resulting in brighter, more stable dots.

Related Articles


Quantum dots are specially engineered nanoscale crystals of semiconductor compounds. The name comes from the fact that their infinitesimal size enables a quantum electronics effect that causes the crystals to fluoresce brilliantly at specific, sharply defined colors. Bright, stable, tiny and tunable across a broad spectrum of colors, quantum dots that are engineered to attach themselves to particular proteins have become a popular research tool in areas such as cancer research for detecting, labeling and tracking specific biomarkers and cells.

Making good quantum dots for biological research is complex. First a semiconductor compound--typically a mixture of cadmium and selenium--must be induced to crystallize into discrete nanocrystals of just the right size. Cadmium is toxic, and the compound also can oxidize easily (ruining the effect), so the nanocrystals must be encapsulated in a protective shell such as zinc sulfide. To make them water soluble for biological applications, a short organic molecule called a "ligand" is attached to the zinc atoms. The organic ligand also serves as a tether to attach additional functional molecules that cause the dot to bind to specific proteins.

The accepted commercial method uses a high-temperature reaction (about 300 degrees Celsius) that must be carefully controlled under an inert gas atmosphere for the crystallization and encapsulation stages. An intermediate ligand material that can tolerate the high temperature is used to promote the crystallization process, but it must be chemically swapped afterwards for a different compound that makes the material water soluble. The ligand exchange step--as well as several variations on the process--is known to significantly alter the luminescence and stability of the resulting quantum dots.

Seeking a better method, NIST researchers turned to microwave-assisted chemistry. Microwaves have been employed in a variety of chemical reactions to reduce the required times and temperatures. Working at temperatures half those of commercial processes, the group developed a relatively simple two-stage process that requires no special atmospheric conditions and directly incorporates the water-soluble ligand into the shell without an exchange step. Using commercially available starting materials, they have synthesized highly uniform and efficient quantum dots for a range of frequencies and shown them to be stable in aqueous solutions for longer than four months.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Roy et al. Emission-tunable microwave synthesis of highly luminescent water soluble CdSe/ZnS quantum dots. Chemical Communications, 2008; (18): 2106 DOI: 10.1039/b800060c

Cite This Page:

National Institute of Standards and Technology. "Low Cost Quantum Dots For Biological Research Produced Through Microwave Synthesis." ScienceDaily. ScienceDaily, 19 June 2008. <www.sciencedaily.com/releases/2008/06/080612095523.htm>.
National Institute of Standards and Technology. (2008, June 19). Low Cost Quantum Dots For Biological Research Produced Through Microwave Synthesis. ScienceDaily. Retrieved February 27, 2015 from www.sciencedaily.com/releases/2008/06/080612095523.htm
National Institute of Standards and Technology. "Low Cost Quantum Dots For Biological Research Produced Through Microwave Synthesis." ScienceDaily. www.sciencedaily.com/releases/2008/06/080612095523.htm (accessed February 27, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, February 27, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vibrating Bicycle Senses Traffic

Vibrating Bicycle Senses Traffic

Reuters - Innovations Video Online (Feb. 26, 2015) Dutch scientists have developed a smart bicycle that uses sensors, wireless technology and video to warn riders of traffic dangers. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
In Japan, Robot Dogs Are for Life -- And Death

In Japan, Robot Dogs Are for Life -- And Death

AFP (Feb. 25, 2015) Robot dogs are the perfect pet for some in Japan who go to repairmen-turned-vets when their pooch breaks down - while a full Buddhist funeral ceremony awaits those who don&apos;t make it. Duration: 02:40 Video provided by AFP
Powered by NewsLook.com
London Show Dissects History of Forensic Science

London Show Dissects History of Forensic Science

AFP (Feb. 25, 2015) Forensic science, which has fascinated generations with its unravelling of gruesome crime mysteries, is being put under the microscope in an exhibition of real criminal investigations in London. Duration: 00:53 Video provided by AFP
Powered by NewsLook.com
Researchers Replace Damaged Hands With Prostheses

Researchers Replace Damaged Hands With Prostheses

Newsy (Feb. 25, 2015) Scientists in Austria have been able to fit patients who&apos;ve lost the use of a hand with bionic prostheses the patients control with their minds. Video provided by Newsy
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