Carbon Dots Newest Member of Brightly Luminescent Nanoparticle Family

Jun 05, 2006

Chemists at Clemson University have developed a new type of quantum dot that is the first to be made from carbon. Like their metal-based counterparts, these nanoscale "carbon dots" glow brightly when exposed to light and show promise for a broad range of applications, including improved biological sensors and medical imaging devices. The carbon-based quantum dots may be less toxic and less expensive than metal-based quantum dots. This work appears in the Journal of the American Chemical Society.

"Carbon is hardly considered to be a semiconductor, so luminescent carbon nanoparticles are very interesting both fundamentally and practically," says study leader Ya-Ping Sun, Ph.D. "It represents a new platform for the development of luminescent nanomaterials for a wide range of applications."

Quantum dots have generated much interest in recent years, especially for potential applications in biology and medicine. These tiny particles have been developed from compounds composed of lead, cadmium and, more recently, silicon. But these materials have raised concerns over potential toxicity and environmental harm, though investigators have developed a variety of approaches for encapsulating these semiconductor nanoparticles in polymers to render them inert. Nevertheless, scientists continue searching for more benign compounds for making quantum dots.

Researchers have known for some time that carbon nanoparticles, due partly to their enormous surface area, have unusual chemical and physical properties quite different from their bulk form. Using nanoparticles produced from graphite, the Clemson investigators demonstrated that when these carbon nanoparticles are covered with special polymers, they glow brightly when exposed to light. The dots glow continuously as long as a light source is present.

The scientists believe that this photoluminescence may be due to the presence of "pockets," or holes, on the surface of the carbon dots that trap energy. The polymer coating acts as a "molecular band-aid," enabling light emission from the inside of the polymer casing, the investigators note. Scientists believe that metal-based quantum dots emit light by a different mechanism.

The polymer coating also allowed the investigators to attach antibodies and other labeling materials to the carbon dot, opening the door to the development of sensors that light up in the presence of tumors or even precancerous cells. In lab studies, the researchers successfully labeled anthrax-like spores with luminescent carbon dots, resulting in glowing spores that were easily viewed under a microscope.

This work is detailed in a paper titled, “Quantum-sized carbon dots for bright and colorful photoluminescence.” This paper was published online in advance of print publication. An abstract is available at the journal’s website.

Source: National Cancer Institute

Explore further: Optically activating a cell signaling pathway using carbon nanotubes

Related Stories

GPS-loaded helmet offers easier trip for motorcyclists

Dec 30, 2014

An Android-based motorcycle helmet with GPS and voice-control has won the confidence of project supporters. The company is preparing to roll out its creation next year. Russian startup Livemap is behind this ...

Can technology stop scourge of bicycle thefts?

Jan 21, 2015

Urban cyclists have more in common than an aptitude for pedaling through city streets - they share the ever-present dread of one day discovering their bicycle missing from the bike rack, or finding only the skeletal remains ...

OLED experts to advance improved production techniques

Oct 08, 2014

Back in May, Steven Shankland in CNET said that, for the lighting business, "the next technology is coming: OLED (organic light-emitting diode) lighting. It replaces the small, bright dots of LEDs with sheets of light that aren't so piercingly bright." Now MIT Technolog ...

Recommended for you

Designer's toolkit for dynamic DNA nanomachines

Mar 26, 2015

The latest DNA nanodevices created at the Technische Universitaet Muenchen (TUM)—including a robot with movable arms, a book that opens and closes, a switchable gear, and an actuator—may be intriguing ...

Simple method of binding pollutants in water

Mar 26, 2015

New types of membrane adsorbers remove unwanted particles from water and also, at the same time, dissolved substances such as the hormonally active bis-phenol A or toxic lead. To do this, researchers at the ...

Gold nanoparticles for targeted cancer treatment

Mar 26, 2015

The use of tiny drug-loaded nanocarriers for the safe, targeted delivery of drugs to designated parts of the body has received much press in recent years. Human trials of nanocarriers targeting pancreatic ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.