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CNR: Alamanacco della Scienza


N. 9 - 23 mag 2012

International info   a cura di Cecilia Migali


Innovative biosensor for medical diagnostics

An ultrasensitive biosensor carried out by researchers of Purdue University (Usa) will reveal cancer at an early stage, permitting a 'personalized medicine' tailored to the specific biochemistry of individual patients.

"The device, which could be several hundred times more sensitive than other biosensors, combines the attributes of two distinctly different types of sensors", says Muhammad A. Alam, a Purdue University professor of electrical and computer engineering and co-author of the paper. "Individually, both of these types of biosensors have limited sensitivity, but when you combine the two you get something that is better than either".

The innovative tool, called a Flexure-Fet biosensor,  combines a mechanical sensor, which identifies a biomolecule based on its mass or size, with an electrical sensor that identifies molecules based on their electrical charge. The new sensor detects both charged and uncharged biomolecules, allowing a broader range of applications than either type of sensor alone. It has two potential applications: personalized medicine, in which an inventory of proteins and Dna is recorded for individual patients to make more precise diagnostics and treatment decisions; and the early detection of cancer and other diseases. "In early cancer diagnostics, the sensor makes possible the detection of small quantities of Dna fragments and proteins deformed by cancer long before the disease is visible through imaging or other methods", Alam adds.

The sensor's mechanical part is a vibrating cantilever, a sliver of silicon that resembles a tiny diving board. Located under the cantilever is a transistor, which is the sensor's electrical part. The sensor maximizes sensitivity by putting both the cantilever and transistor in a 'bias'. The cantilever is biased using an electric field to pull it downward as though with an invisible string. "This pre-bending increases the sensitivity significantly", says Ankit Jain, co-author of the paper.

A U.S. patent application has been filed for the concept.  The work has been funded by the U.S. Department of Defense, U.S. Department of Energy, National Institutes of Health-Prism center at Purdue's Discovery Park, and the Semiconductor Research Consortium through the Msd center at the Massachusetts Institute of Technology.


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