Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Twinkle, twinkle, quantum dot -- new particles can change colors and tag molecules

Engineers at Ohio State University have invented a new kind of nano-particle that shines in different colors to tag molecules in biomedical tests.

These tiny plastic nano-particles are stuffed with even tinier bits of electronics called quantum dots. Like little traffic lights, the particles glow brightly in red, yellow, or green, so researchers can easily track molecules under a microscope.

This is the first time anyone has created fluorescent nano-particles that can change colors continuously.

Jessica Winter, assistant professor of chemical and biomolecular engineering and biomedical engineering, and research scientist Gang Ruan describe their patent-pending technology in the online edition of the journal Nano Letters.

Researchers routinely tag molecules with fluorescent materials in order to see them under the microscope. Unlike the more common fluorescent molecules, quantum dots shine very brightly, and could illuminate chemical reactions especially well, allowing researchers to see the inner workings of living cells.

A bottleneck to combating major diseases like cancer is the lack of molecular or cellular-level understanding of biological processes, the engineers explained.

“These new nanoparticles could be a great addition to the arsenal of biomedical engineers who are trying to find the roots of diseases,” Ruan said.

“We can tailor these particles to tag particular molecules, and use the colors to track processes that we wouldn’t otherwise be able to,” he continued. “Also, this work could be groundbreaking for the field of nanotechnology as a whole, because it solves two seemingly irreconcilable problems with using quantum dots.”

Quantum dots are pieces of semiconductor that measure only a few nanometers, or billionths of a meter, across. They are not visible to the naked eye, but when light shines on them, they absorb energy and begin to glow. That’s what makes them good tags for molecules.

Due to quantum mechanical effects, quantum dots “twinkle” – they blink on and off at random moments. When many dots come together, however, their random blinking is less noticeable. So, large clusters of quantum dots appear to glow with a steady light.

Blinking has been a problem for researchers, because it breaks up the trajectory of a moving particle or tagged molecule that they are trying to follow. Yet, blinking is also beneficial, because when dots come together and the blinking disappears, researchers know for certain that tagged molecules have aggregated.

“Blinking is good and bad,” Ruan explained. “But one day we realized that we could use the ‘good’ and avoid the ‘bad’ at the same time, by grouping a few quantum dots of different colors together inside a micelle.”

A micelle is a nano-sized spherical container, and while micelles are useful for laboratory experiments, they are easily found in household detergents – soap forms micelles that capture oils in water. Ruan created micelles using polymers, with different combinations of red and green quantum dots inside them.

In tests, he confirmed that the micelles appeared to glow steadily. Those stuffed with only red quantum dots glowed red, and those stuffed with green glowed green. But those he stuffed with red and green dots alternated from red to green to yellow.

The color change happens when one or another dot blinks inside the micelle. When a red dot blinks off and the green blinks on, the micelle glows green. When the green blinks off and the red blinks on, the micelle glows red. If both are lit up, the micelle glows yellow.

The yellow color is due to our eyes’ perception of light. The process is the same as when a red pixel and green pixel appear close together on a television or computer screen: our eyes see yellow.

Nobody can control when color changes happen inside individual micelles. But because the particles glow continuously, researchers can use them to track tagged molecules continuously. They can also monitor color changes to detect when molecules come together.

Winter and Ruan said that the particles could also be used in fluid mechanics research – specifically, micro-fluidics. Researchers who are developing tiny medical devices with fluid separation channels could use quantum dots to follow the fluid’s path.

The same Ohio State research team is also developing magnetic particles to enhance medical imaging of cancer, and it may be possible to combine magnetism with the quantum dot technology for different kinds of imaging. But before the particles would be safe to use in the body, they would have to be made of biocompatible materials. Carbon-based nanomaterials are one possible option.

In the meantime, Winter and Ruan are going to continue developing the color-changing quantum dot particles for studies of cells and molecules under the microscope. They are also going to explore what happens when quantum dots of another color – for instance, blue – are added to the mix.

The university will look to license the technology for industry, and Winter and Ruan have created a Web site for the technologies they are developing:

This research was supported by the National Science Foundation, an endowment from the William G. Lowrie family to the Department of Chemical and Biomolecular Engineering, and the Center for Emergent Materials at Ohio State.

Contacts: Gang Ruan:
Jessica Winter,
[Both Ruan and Winter are best reached by email.]
Written by Pam Frost Gorder, (614) 292-9475;

Jessica Winter | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Strong, steady forces at work during cell division
20.10.2016 | University of Massachusetts at Amherst

nachricht Disturbance wanted
20.10.2016 | Max Delbrück Center for Molecular Medicine in the Helmholtz Association

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>