Biosensor shines a light on cancer

Researchers at the US Department of Energy’s Ames Laboratory have developed a biosensor technology said to provide immediate information about DNA damage from cancer producing compounds. Damage to DNA is a critical first step in the development of cancer.

When carcinogens enter the body and are activated, they can react with the DNA to form DNA adducts, chemical compounds in which the carcinogen is attached to the DNA.

Gerald Small, an Ames Laboratory senior chemist and an Iowa State University professor, and Ryszard Jankowiak, an Ames Laboratory senior scientist, are developing a new means for detection of certain DNA adducts that can be found in urine. The newly developed biosensor chip technique is said to be simpler and potentially more practical than previously developed methods.

The biosensor technology is based on a gold chip, which can be used to detect fluorescent DNA adducts – adducts that emit light when excited by a laser. Bound to the chip’s surface are special antibodies, proteins that serve as the body’s natural defence system against infectious agents.

With the new biosensor chip technology, scientists could test for the presence of certain adducts in a sample of urine by dipping a chip containing the corresponding antibody into processed urine.

Adducts of interest would bind to the antibody and fluoresce when scanned with a laser beam at minus 4 Kelvin. Data gathered from the laser scanning would then be used to produce a detailed fingerprint for adduct identification.

Jankowiak explained that initially they were unable to detect fluorescence at room temperature. However, he noted that the addition of a thin layer of glycerol to the surface of the chip led to a significant increase in fluorescence intensity at room temperature. ‘Cooling the chip further increased the intensity by a factor of 10,’ he said.

The research team is also investigating other enhancements to the biosensor chip technology, including making chips with several addresses for different antibodies that bind different adducts and using surfaces other than gold.

‘We are currently looking at adducts implicated in breast and prostate cancer,’ said Jankowiak. ‘One day this technology, if commercialised, could lead to significant advances in pre-cancer diagnosis.’

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