Biosensor to detect brain injuries during heart surgery

Scientists have developed a fingernail-sized biosensor that could alert doctors when serious brain injury occurs during heart surgery.
Johns Hopkins engineers and cardiology experts teamed up to develop the device and demonstrated in lab tests that the prototype sensor had successfully detected a protein associated with brain injuries.
"Ideally, the testing would happen while the surgery is going on, by placing just a drop of the patient's blood on the sensor, which could activate a sound, light or numeric display if the protein is present," said the study's senior author, Howard E Katz, a Whiting School of Engineering expert in organic thin film transistors, which form the basis of the biosensor.

The project originated about two years ago when Katz, who chairs the Department of Materials Science and Engineering, was contacted by Allen D Everett, a Johns Hopkins Children's Center pediatric cardiologist who studies biomarkers linked to pulmonary hypertension and brain injury.
Everett sought an engineer to design a biosensor that responds to glial fibrillary acidic protein (GFAP), which is a biomarker linked to brain injuries.
"If we can be alerted when the injury is occurring then we should be able to develop better therapies. We could improve our control of blood pressure or redesign our cardiopulmonary bypass machines," Everett said.

"We could learn how to optimise cooling and rewarming procedures and have a benchmark for developing and testing new protective medications," Everett added.

At present, Everett said, doctors have to wait years for some brain injury-related symptoms to appear. That slows down the process of finding out whether new procedures or treatments to reduce brain injuries are effective.
"The sensor platform is very rapid. It's practically instantaneous," Everett said.
To create this sensor, Katz turned to an organic thin film transistor design.
The sensing area is a small square, 3/8ths-of-an-inch on each side. On the surface of the sensor is a layer of antibodies that attract GFAP, the target protein.

When this occurs, it changes the physics of other material layers within the sensor, altering the amount of electrical current that is passing through the device.
These electrical changes can be monitored, enabling the user to know when GFAP is present.
"This sensor proved to be extremely sensitive. It recognised GFAP even when there were many other protein molecules nearby. As far as we've been able to determine, this is the most sensitive protein detector based on organic thin film transistors," Katz said.
The study was published in the journal Chemical Science.