Gold nano-antennas reveal single molecules' electrochemical properties

February 28, 2017 by Erik Arends, Leiden Institute of Physics
At both ends of the nanorod (yellow), the electromagnetic field of light is amplified by a factor 500 (red spots). If a molecule (blue dots) is situated there, its fluorescent signal is also 500 times stronger. Credit: Leiden Institute of Physics

Individual molecules are extremely hard to see through feeble fluorescence. Leiden physicists have managed to use tiny gold nanorods as antennas to intensify their signal 500 times. They have published their results in Angewandte Chemie.

In the early 1980's, IBM created a world-famous picture of individual particles spelling out the company's name. They used a scanning tunneling microscope to image single particles for the first time. A decade later, scientists managed to see molecules using visible light by picking up on the molecules' fluorescence. Physicist Michel Orrit from Leiden University (Netherlands) was one of those pioneers.

Now, Orrit and his group have further developed that research, using tiny antennas to amplify the signal for better visualization. Instead of a large metal antenna for radio waves, they used a small rod to catch waves. This gold nanorod—40 x 80 nanometers in size—locally intensifies the electromagnetic field of light at both ends. If a molecule is situated at either end, it will fluoresce 500 times more strongly than without the rod.

Orrit's group published an article in Angewandte Chemie in which they described how they tested their concept on so-called redox reactions. These occur in any type of electric process, for example in solar cells. "We tested on redox reactions as a proof of concept," says Martin Caldarola, one of the authors. "At the same time, redox reactions are a very interesting application of our technique for many scientists, because they occur in so many processes."

Credit: Leiden Institute of Physics

Caldarola tested the technique by determining the redox midpoint potential—a crucial indicator for a material's ability to perform . This offers, for example, its applicability for . The new method enables researchers to resolve the midpoint potential for each molecule, so they can investigate materials very precisely.

Explore further: Single molecule detected for use in quantum network

More information: M.Sc. Weichun Zhang, Dr. Martín Caldarola, M.Sc. Biswajit Pradhan, Prof. Dr. Michel Orrit, 'Gold Nanorod-Enhanced Fluorescence Enables Single-Molecule Electrochemistry of Methylene Blue', Angewandte Chemie

Related Stories

Single molecule detected for use in quantum network

April 4, 2016

Leiden physicists have detected a single molecule called dibenzoterrylene in a new crystal and found that it is a candidate component for a quantum network. Future quantum computers will need such a network to work together ...

Oxygen takes elitist attitude to sharing electrons

November 23, 2016

Fuel cells, metal-air batteries, and other devices use electron-exchanging reactions involving gaseous oxygen. To improve these technologies, scientists need to know how the oxygen behaves when it encounters the catalyst, ...

Recommended for you

Detecting metabolites at close range

June 22, 2018

A novel concept for a biosensor of the metabolite lactate combines an electron transporting polymer with lactate oxidase, which is the enzyme that specifically catalyzes the oxidation of lactate. Lactate is associated with ...

CryoEM study captures opioid signaling in the act

June 22, 2018

Opioid drugs like morphine and fentanyl are a mainstay of modern pain medicine. But they also cause constipation, are highly addictive, and can lead to fatal respiratory failure if taken at too high a dose. Scientists have ...

Researchers achieve unprecedented control of polymer grids

June 21, 2018

Synthetic polymers are ubiquitous—nylon, polyester, Teflon and epoxy, to name just a few—and these polymers are all long, linear structures that tangle into imprecise structures. Chemists have long dreamed of making polymers ...

Template to create superatoms could make for better batteries

June 21, 2018

Virginia Commonwealth University researchers have discovered a novel strategy for creating superatoms—combinations of atoms that can mimic the properties of more than one group of elements of the periodic table. These superatoms ...


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.