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Purdue Biosensor Measures Neuron Performance to Test Epilepsy Treatments

A self-referencing glutamate nano type of biosensor has been developed by Purdue University’s associate professor in agricultural and biological engineering and biomedical engineering, Marshall Porterfield; Subhashree Mohanty, a graduate student; and Eric McLamore, a postdoctoral researcher.

This biosensor can be used for the measurement of glutamate flux surrounding the neural cells of a living organism in real time. It can also indicate the manner in which these cells take up or release glutamate, a crucial issue related to the activity and health of a cell. Researchers can use this sensor as a tool for testing the effectiveness of new seizure or epilepsy treatments.

Any movement or action in a human body involves the firing of neurons. Neurons function electrically and communicate messages through chemical neurotransmitters like glutamate. The glutamate is released by a neuron for conveying information to the succeeding cell receptors of the neuron. Neurons are likely to clear or reabsorb the glutamate signal when the message is delivered. It is likely that people would be prone to neurological diseases when neurons release too much or too little glutamate and are unable to properly clear it.

McLamore and Porterfield’s sensor that exploits conductive carbon nanotubes is a mere 2 µm in diameter, or nearly 50 times smaller as compared to a human hair’s diameter. Glutamate oxidase, an enzyme, is utilized at the probe’s end which reacts with glutamate and generates hydrogen peroxide. The hydrogen peroxide’s conductivity is increased by the carbon nanotubes. The glutamate movement with respect to the surface of the cell can be calculated by a computer. The glutamate’s concentration activities for a range of positions with respect to the neurons present in the culture is sampled by the oscillating sensor. Researchers can know if the glutamate is dissipating in multi-directions or is flowing back to the neurons through these measurements conducted at varying distances.

Existing sensor technology permits sensing in vitro, but with invasive and large probes and is unable to measure the chemicals’ movement, according to Porterfield

McLamore informed that this sensor can hone on directly to the glutamate through customized software and a single probe for filtering signal variations, resulting in signal noise caused by compounds to be eliminated. He added that various compounds surrounding the neurons are likely to generate noise, and the sensor will have to be selective relative to a particular compound. He revealed that the background noise is filtered like modern-day hearing aids. The sensor should be able to measure other chemicals through changing the enzyme utilized on the tip.

The versatility of the sensor could help to understand the efficacy of therapies for treating epilepsy, memory loss, Parkinson’s disease, damage due to chemotherapy, and various other conditions, according to Rickus. The sensors will provide useful data on the manner in which the damaged neurons work and how cells are affected by therapies or drugs.
In the next stage, minor enhancements will be incorporated in the sensor for making it adaptable for using on other enzymes.

The research was funded by the Office of Naval Research.


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