Enzyme-Based Electrochemical Glutamate Biosensors

Abstract

Glutamate, a major excitatory neurotransmitter in the mammalian central nervous system, plays a vital role in many physiological processes and is one of the key neurotransmitters of interest in psychopharmacology. It is involved in many normal and abnormal behaviors related to neurological and psychiatric disorders. The glutamate system has been proposed to play a significant role in various neurological and psychiatric disorders such as Alzheimer's disease, autism, schizophrenia, depression, drug addiction, and more. The design, construction, and optimization of enzyme-based electrochemical biosensors for in vivo and in vitro detection of glutamate are active areas of interdisciplinary research. For example, various glutamate biosensors have been developed for monitoring dynamic levels of extracellular glutamate in the living brain tissue adding to the current medical knowledge of these complex neurotransmitter systems and ultimately impacting treatment plans. In addition to biological sciences and clinical medicine, glutamate biosensors have been used in environmental monitoring, in the fermentation industry, and in the food industry for determination of monosodium glutamate (MSG), a common flavor-enhancing food additive.

“Nano”: An Emerging Avenue in Electrochemical Detection of Neurotransmitters

“…(65) It is a nonessential amino acid and acts as an excitatory neurotransmitter. (66) It is also used as a food additive and leads to "Chinese-restaurant syndrome" presently referred to as the monosodium glutamate (MSG) syndrome. (67) Glutamate is distributed throughout the central nervous system and mediates several functions in the brain that involve learning and memory.…”

“…Glutamate is the precursor of GABA and plays a vital role in the pathophysiology of neurotransmitter disorders . It is a nonessential amino acid and acts as an excitatory neurotransmitter . It is also used as a food additive and leads to “Chinese-restaurant syndrome” presently referred to as the monosodium glutamate (MSG) syndrome .…”

Recent Advances in the Detection of Neurotransmitters

“…Some neurotransmitters such as glutamate and acetylcholine are hard to detect via the electrochemical method because of their non-electroactive properties. However, the present of enzymes could convert the neurotransmitters to produce H 2 O 2 , which is easy to detect [87,88]. Enzymes are also selective towards target analyte, which improves the performance of the neurotransmitter sensor.…”

A Highly Sensitive Amperometric Glutamate Oxidase Microbiosensor Based on a Reduced Graphene Oxide/Prussian Blue Nanocube/Gold Nanoparticle Composite Film-Modified Pt Electrode

“…Many analytical techniques, such as fluorometric [10], spectrophotometric [11], chromatographic [12], and colorimetric methods [13], have been developed to measure glutamate in neurochemical analysis applications. Despite their high sensitivity, these methods still have not been widely applied in practical applications because of certain limitations, including high labor intensity, being overly time consuming, requiring expert handling, and involving sample pre-treatment [14]. Due to excellent analytical properties of resolution, sensitivity, and selectivity, electrochemical methods are considered as one of the most potential approaches for sensing of neurotransmitters [15].…”