A New Perspective on Using Glycols in Glutamate Biosensor Design: From Stabilizing Agents to a New Containment Net

Glutamate is a major excitatory neurotransmitter in the brain. It is involved in many
normal physiological brain activities, but also neurological disorders and excitotoxicity. Hence,
glutamate measurement is important both in clinical and pre-clinical studies. Pre-clinical studies
often use amperometric biosensors due to their low invasiveness and the relatively small size of the
devices. These devices also provide fast, real-time measurements because of their high sensitivity.
In the present study, diethylene glycol (DEG), neopentyl glycol (NPG), triethylene glycol (TEG),
and glycerol (GLY) were used to increase the long-term stability of glutamate biosensors. The
evaluation was made by measuring variations of the main enzymatic (VMAX and KM) and analytical
(Linear Region Slope (LRS)) parameters. Of the glycols tested, TEG was the most promising
stabilizer, showing about twice as high VMAX maintained over a greater duration than with other
stabilizers tested. It is also yielded the most stable linear region slope (LRS) values over the study
duration. Moreover, we highlighted the ability of glycols to interact with enzyme molecules to form
a containment network, able to maintain all the layered components of the biosensor adhering to
the transducer.