Ohio State University scientists have successfully tested a biosensor designed to detect biomarkers associated with traumatic brain injury.
In a study published in Smallthe researchers said their waterproof biosensor contains an “unprecedented combination of features” that could allow it to detect changes in the concentrations of various chemicals in the body and send the results to researchers in real time.
The chip is said to be flexible and thinner than a human hair, making it minimally invasive for use in the brain.
In a statement, co-author Jinghua Li, an assistant professor of materials science and engineering at Ohio State, said, “We still have a long way to go from our testing in the lab, but these findings were very encouraging.”
The biosensor could have many potential applications, but Li and her co-authors were particularly focused on how it could be used to monitor patients with traumatic brain injury (TBI).
After TBI, secondary damage can occur that can be detected by changes in the sodium and potassium ion concentrations in the cerebrospinal fluid, said Li, who is a member of Ohio State Chronic Brain Injury (CBI) Program†
The researchers tested the biosensor in an artificial solution they created to mimic cerebrospinal fluid and found that it could accurately detect changes in potassium and sodium ion levels that are important in TBI.
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In addition to the tests with the artificial cerebrospinal fluid, the team also tested the biosensor in human blood serum, successfully checking the pH levels.
The chip features field effect transistors that, upon detecting the chemical in question, produce an electrical signal that can be detected and analyzed outside the body. Importantly, the researchers developed calibration standards to address crosstalk.
“When we make a biochemical sensor, we want to make sure that the device only responds to the specific chemicals we’re interested in, ignoring the crosstalk of other biomarkers,” Li said. “That’s hard to do in a complex system like our bodies.”
While a biosensor should be able to detect changes in the fluids in the brain, the electronics in the chip must be protected from the same fluids, Li said.
A waterproof encapsulation made of a thin film of silicon dioxide — forged at temperatures above 1,000 degrees Celsius — ensured high structural integrity as a barrier material in a liquid environment, the study found.
Tests involve placing the biosensor in heated liquids and in substances with different pH values. The findings suggest that the waterproof encapsulation several hundred nanometers thick could last at least a few years at body temperature and possibly much longer, Li said.
The biggest problem right now is with the chemical detection elements, which the study suggests would only work for a few weeks.
Li said other issues need to be solved before the biosensor is ready to be tested in animal models and humans. The response of biotissues to the sensor over an extended period of time needs further investigation. There are still issues with crosstalk that need to be addressed, given the complexity of the biosystem and questions about how to mass-produce the sensors.
However, the study provides more evidence that the sensors have a future in healthcare, she said.
Li said she believes biosensors could be used to analyze not only ions and neurotransmitters, as in this study, but possibly peptides, proteins, nucleotide acids and other chemicals in the body. It could be a breakthrough not only for TBI, but also for other chronic diseases such as Parkinson’s and Alzheimer’s.
