NEW TECHNOLOGY FOR CANCER SCREENING LISTENS FOR THE SIGNS OF CANCER

RESEARCHERS FROM THE GEORGIA INSTITUTE OF TECHNOLOGY HAVE CREATED an acoustic sensor that can report the presence of small amounts of mesothelin, a molecule associated with a number of cancers including mesothelioma, as they attach to the sensor's surface.

According to the researchers, the study is a proof of principle, demonstrating a technique that might work for the detection of nearly any biomarker — a collective term for a molecular signal that denotes the presence of disease.

"It is one thing to be able to identify biomarkers for a disease, but it is another to be able to find them in blood quickly and easily at very low concentrations," said Anthony Dickherber, a graduate student in the School of Electrical and Computer Engineering at Georgia Tech. "We envision that, one day, doctors can use an array of our sensors as a sort of laboratory in their office, where they could use a quick blood sample to detect or monitor the signs of cancer."

Responding to the growing need for such sensors in both research and clinical practice, researchers developed the ACuRay chip, standing for ACoustic micro- arRay.

The array consists of a series of electrodes deposited on the surface of a thin film of zinc oxide, which allows the device to resonate, or vibrate, at a specific frequency when a current is applied, much like the quartz timing devices used in many clocks and watches.

"The sensor itself is built on a base of silicon, like a computer chip, and could be mass-produced using very wellknown and inexpensive microelectronic fabrication techniques," Dickherber explained.

To turn this array into a sensor, the Georgia Tech researchers coated the zinc oxide surface with mesothelinspecific antibodies generated in the lab of Ira Pastan, M.D., at the National Cancer Institute. These molecules are engineered versions of the antibodies that the immune system creates to identify foreign intruders, such as microbial parasites. In this study, the researchers coated the sensor with antibodies for mesothelin, a cell-surface protein that is highly expressed in mesothelioma, ovarian cancer, pancreatic cancer and other malignancies.

When the mesothelin binds to an antibody, the added mass changes the frequency at which the acoustic wave passes between the electrodes on the surface of the device. The device is able to "hear" the pitch change due to nanomolar concentrations of mesothelin binding to antibodies on the chip. The technology has the potential of detecting biomarkers in even lower concentrations than those tested, Dickherber said.