Researchers from the Georgia Institute of Technology have created ACuRay™ (stands for standing for ACoustic micro-arRay), an acoustic sensor that can detect small amounts of mesothelin, a molecule associated with a number of cancers including mesothelioma. The device consists of an array of electrodes on the surface of a thin film of zinc oxide, which resonate, or vibrate, at a specific frequency when a current is applied, much like the quartz timing devices used in many clocks and watches.

To turn this array into a sensor, the Georgia Tech researchers coated the zinc oxide surface with mesothelin-specific antibodies generated in the lab of Ira Pastan, M.D., at the National Cancer Institute. These molecules are engineered versions of the antibodies 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 (just a few molecules amid billions) binding to antibodies on the chip. The technology has the potential of detecting biomarkers in even lower concentrations than those tested, Dickherber said.

The authors say that the sensor is built on a base of silicon, like a computer chip, and could be mass-produced using very well known and inexpensive microelectronic fabrication techniques and with further refinement, could readily lead to an inexpensive, ubiquitous technology for researchers, physicians and the clinical laboratory.