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The innovative work was a collaboration between several ASU departments and the Univesidad Nacional de Rio Cuarto in Argentina. In addition to Fisher, who was lead author on the paper, contributions from chemistry and biochemistry professors Devens Gust, Tom Moore and Ana Moore of ASU's Center for the Study of Early Events in Photosynthesis were instrumental in the project.

"The initial interest was to more fully understand how photosynthesis works," said Fisher. Because our center focuses on electron transport in a single molecule, Devens Gust and Tom and Ana Moore suggested that we look at single molecule transport in carotene."

To get at the heart of the problem, Fisher had to attempt an experiment that had never been done before for any biomolecule: to control the charge of the biomolecule while measuring its ability to hold a current.

By holding a carotenoid under potential control, Fisher could control whether the biomolecule was in a neutral state or in the charged state (the oxidized state), while simultaneously measuring the electron transport through a single molecule.

"The importance of this result is not only for understanding natural systems and photosynthesis, but also for the fact that technically, for the first time, we could hold a molecule in a state pretty close to the natural conditions found in the plant," said Fisher.

To make the experimental measurements, Fisher first needed to work out several technically challenging variations to a method first pioneered by electrical engineering professor Nongjian Tao of ASU's Fulton School of Engineering. In concept, it's much like trying to measure the current of a wire found in an everyday household appliance, only in this case, the "wiring" is a miniscule 2.8 nanometers long and less than a single nanometer thick, or about 10,000 times smaller than the width of a human ha
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Source:Arizona State University