Biosensor Detects Chemical
Researchers are hoping a new biosensor may help farmers and regulatory
officials detect herbicides in soil and water samples. The device relies on
living organisms or their byproducts to identify traces of chemical residues in
a matter of minutes.
Heavy applications of herbicides can leave environmentally unsafe residues
in soil and water. The biosensor is made of a chlorophyll-protein complex--the
green proteins in plants used for photosynthesis--fixed on electrodes that
specifically measure oxygen levels. The complex produces oxygen in the presence
of certain chemicals and light.
A liquid sample is passed through the biosensor. If the sample contains a
herbicide, the chemical will react with the biosensor's proteins and inhibit
oxygen production. The electrode in the biosensor detects oxygen levels and
sends the information to a computer that displays the data in graph form.
The test is ultrasensitive and works well at room temperature or above. But
"the chlorophyll-protein complex from plants such as potatoes, peas, and
broad beans can't withstand high temperatures, so they are unsuitable for use
as biosensors," says molecular biologist Autar K. Mattoo who heads the
Agricultural Research Service Vegetable
Laboratory in Beltsville, Maryland.
The new device instead uses a protein complex from a particular
cyanobacteriuma bacterium that can fix carbon dioxide in the presence of light
and can grow at very high temperatures--that isn't inactivated at warmer
temperatures a user might encounter in the field.
"If a biosensor is to be used repeatedly, especially in the field, it
requires a biosensing device that is stable at ambient temperatures and doesn't
require cooling," says Mattoo.
The new biosensor is easy to use and economical--distinct advantages over
currently available herbicide detectors. "Other sensors are
reliable," says Mattoo. "But they require expensive equipment and lab
analysis, limiting the number of samples that can be analyzed."
This biosensor can run repeated tests in the field. The scientists are
working on a miniaturized commercial version that should be available within
the next 2 to 3 years. Mattoo co-developed the biosensor with scientists from
the Czech Republic and Italy through a grant supported by the North Atlantic
Treaty Organization. More detailed information about this research will soon be
published in the journal "Biotechnology and Bioengineering."--By
Tara Weaver, Agricultural
Research Service Information Staff.
Autar K. Mattoo is at the
Laboratory, Bldg. 010A, Room 246, 10300 Baltimore Ave., Beltsville, MD
20705-2350; phone (301) 504-7380, fax (301) 504-5555.
"Biosensor Detects Chemical Residues" was published in the
November 1998 issue of Agricultural Research magazine. Click here to see this
issue's table of contents.