A Novel Real-Time, Mediator-Free, Non-Enzymatic Electrochemical Biosensor for Glutamate Detection

Glutamate is the major excitatory neurotransmitter in the brain, and an excess of glutamate can cause excitotoxicity, which is a common pathological process in many neurologic disorder such as stroke, brain trauma, and brain tumor. Therefore, monitoring glutamate in real time is of critical importance.  However, the existing methods for the detection and monitoring glutamate levels are limited.  Here in this work, we present a novel mediator-free, non-enzymatic electrochemical biosensor for real-time glutamate monitoring, based on immobilization of genetically engineered periplasmic glutamate binding protein onto gold nanoparticle-modified screen-printed carbon electrodes. Cyclic voltammetry is performed to determine the glutamate concentration in phosphate buffer solution (pH=7.4). The results show an excellent sensitivity with 0.1µM detection limit and the linearity was investigated in the 0.1µM-1µM range of glutamate concentration. The sensor was tested with common interfering substances such as aspartate, glutamine, serine, lysine and ascorbic acid, and exhibited high selectivity toward glutamate over those substances.