Laboratory develops cancer biosensors

In Yale’s Becton Engineering and Applied Science Center, sensors smaller than a child’s fingernail can detect cancer-indicating proteins in blood at a concentration equivalent to a grain of salt dissolved in an Olympic-sized swimming pool.

Researchers in electrical engineering and applied physics professor Mark Reed’s laboratory have been improving and testing biosensors for cancer detection. While Reed said his ultimate goal is to build a foundation for the future generation of bioelectronics, cancer biosensors were one of the applications that developed along the way.

“I’m not a doctor,” Reed said. “I’m a device guy.”

With computer chips reaching their size limit, Reed said he has been building devices to understand how biological systems such as the brain transmit information at the cellular level. Since biological systems rely on biochemical as well as electrical signaling, if researchers want to understand how cells compute, they need to understand the environment in which the cell functions, Reed said. Based on the fact that the smaller a device is, the more sensitive it is, Reed said his team — who also worked with researchers in biomedical engineering and chemical & environmental engineering professor Tarek Fahmy’s laboratory — was able to design devices that are “tremendously” sensitive detectors of biological molecules, such as proteins and cancer markers.

The devices look like regular, though tiny, processing chips, but lying across their flat surfaces are sensors made of nanowires with protruding receptors built to respond to a specified protein, said Aleksandar Vacic GRD ’11, a graduate student in Reed’s laboratory who designs and builds the sensors.

To build these devices, Vacic dons a sanitized, white plastic “bunny suit” as he uses chemicals to carve biosensors on discs of pure, shiny silicon. Since traditional electronic devices are not meant to work in water, Vacic said the laboratory is designing the sensors so liquid will not seep into them.

“Changing the material on top of the sensor that covers the nanowire can increase sensitivity and durability,” he said.

Once the protein binds to the receptor, electrical signals surge though wires connecting the chip to a computer and are recorded on a graph, said Nitin Rajan GRD ’13, who wrote the software and built the hardware for the detection program. Rajan said he is working on eliminating any background noise that can interfere with the sensor’s signals.

Although the chips currently hold a maximum of 10 sensors, they have the potential to hold millions of sensors that detect a variety of diseases, Reed said. But for now, his laboratory is primarily interested in the technological aspects of the device, which could help other researchers develop alternative electronics.

“Maybe there are some things biology will inspire me to do that I haven’t thought of yet,” Reed said.

Reed began working on biosensors four years ago.

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