Ames, IA —Researchers at Iowa State University (ISU) in the U.S. Department of Energy's Ames Laboratory have developed a gold biosensor chip that can be used to detect fluorescent DNA adducts (chemical compounds in which carcinogens attach to DNA). The chip promises to be a practical and simple way to test for adducts found in such bodily fluids as urine.
"By tracking DNA adducts, we can study critical events in tumor initiation, and can identify the particular adduct," says Ryszard Jankowiak, an Ames Laboratory senior scientist who leads the biosensor chip project. "It shows great potential to study susceptibility to breast, prostate, and lung cancer."
To construct the new gold biosensor chip developed at Ames Laboratory for tracking DNA adducts, a gold-coated silicon wafer gets exposed to a number of chemicals that allow it to bind DNA adducts to its surface prior to exposure to low temperature for spectroscopic study.
Jeremy Kenseth, who recently received his Ph.D. at ISU, constructed the actual chip as follows:
He first exposed a gold-coated silicon wafer to a special polymer stamp (polydimethylsiloxane) soaked with octadecanethiol (ODT), a compound that cannot unite with nor absorb water
In the center of the stamp, he cut a 0.5 cm hole to allow "inking" of the outer portions of the chip with ODT, to form an island to which selected antibodies may later bind
He then dipped the chip into DSU, a linker molecule that adsorbed to the bare gold parts and formed a reactive linker molecule that reacts with protein
To use the chip to track adducts, it's exposed to a drop of solution containing a specific monoclonal antibody. The antibody chemically binds through the linker and creates an active surface that can bind the corresponding adduct from solution. When the treated chip is exposed to a solution containing the adduct of interest, the adduct should bind selectively.
At this point, researchers cover the chip with a thin layer of glycerol, lower the temperature to -452F (4 Kelvin), and study the chip spectroscopically. The adduct fluoresces when exposed to a laser beam.
For more information about sensor chips from Ames Laboratories: Enter 537