10-04 :: April 2010

nanotimes

News in Brief

47

Bioelectricity //

Researchers Find Electrical Current Stemming From Plants

In an electrifying first, Scientists from Stanford

University, USA, and Yonsei University, Republic of Korea, have plugged in to algae cells and har- nessed a tiny electric current. They found it at the

very source of energy production – photosynthesis, a plant‘s method of converting sunlight to chemical energy. The Stanford research team developed a unique, ultra-sharp nanoelectrode made of gold, spe- cially designed for probing inside cells. They gently pushed it through the algal cell membranes, which sealed around it, and the cell stayed alive. From the photosynthesizing cells, the electrode collected electrons that had been energized by light and the researchers generated a tiny electric current.

“We believe we are the first to extract electrons out of living plant cells,” said WonHyoung Ryu, the lead author of the paper. Ryu conducted the experiments while he was a research associate for mechanical engineering professor Fritz Prinz. “We‘re still in the scientific stages of the research,” said Ryu. “We were dealing with single cells to prove we can harvest the electrons.”

In this experiment, the researchers intercepted the electrons just after they had been excited by light and were at their highest energy levels. They placed the gold electrodes in the chloroplasts of algae cells, and siphoned off the electrons to generate the tiny

electrical current. The result, the researchers say, is electricity production that doesn‘t release carbon into the atmosphere. The only byproducts of photo- synthesis are protons and oxygen.

“This is potentially one of the cleanest energy sources for energy generation,” Ryu said. “But the question is, is it economically feasible?”

Ryu said they were able to draw from each cell just one picoampere, an amount of electricity so tiny that they would need a trillion cells photosynthesi- zing for one hour just to equal the amount of energy stored in a AA battery. In addition, the cells die after an hour. Ryu said tiny leaks in the membrane around the electrode could be killing the cells, or they may be dying because they‘re losing out on energy they would normally use for their own life processes. One of the next steps would be to tweak the design of the electrode to extend the life of the cell, Ryu said.

WonHyoung Ryu, Seoung-Jai Bai, Joong Sun Park, Zubin Huang, Jeffrey Moseley, Tibor Fabian, Rainer J. Fasching, Arthur R. Grossman and Fritz B. Prinz: Direct Extraction of Photosynthetic Electrons from Single Algal Cells by Nano- probing System, In: Nano Letters, Vol. 10(2010), Issue 4, April 14, 2010, Pages 1137-1143, DOI:10.1021/ nl903141j: http://dx.doi.org/10.1021/nl903141j