Pulickel Ajayan, professor of materials science and engineering at Rensselaer, and geobiologist Ronald Oremland reported that three different kinds of common bacteria "grow" the element selenium in the form of uniform nanospheres. The nanoscopic balls exhibit vastly different properties than selenium that is found as a trace mineral in topsoil.
Selenium is used in photovoltaic and photoconductive technologies. It is incorporated in many electronic and technical applications, such as semiconductors, photocopiers, and photocells.
The findings of Ajayan and Oremland were published in the journal Applied and Environmental Microbiology (an American Society of Microbiology publication) in January. A summary of the research also was featured the same month in the "Editor's Choice" section of Science magazine.
Oremland, a senior scientist at the U.S. Geological Survey in Menlo Park, Calif., and a 1968 Rensselaer biology graduate, has been studying anaerobic bacteria that respire, or "breathe," soluble salts, or "oxyanions," of toxic elements, such as selenium and arsenic. He recently discovered that some of these microbes form distinctive selenium nanoscopic balls, each of which measure 300 nanometers in diameter on the outside of their cell envelopes.
Knowing little about what kinds of properties selenium exhibits on the nanoscale level, Oremland turned to his alma mater to enlist the help of Ajayan, an internationally known nanomaterials expert.
"I was interested in finding out whether this type of selenium would be useful. As a biologist, I am not familiar with the various electrical, optical, and other properties of nanomaterials,
Contact: Jodi Ackerman
Rensselaer Polytechnic Institute