A Critical Review on Non-Enzymatic Electrochemical Strategies for L-Glutamate Monitoring in Biological Systems

An essential excitatory neurotransmitter and metabolic intermediary, L-glutamate is vital for multiple physiological functions, such as memory, learning, and synaptic transmission. A variety of neurological and neurodegenerative conditions have been attributed to aberrant glutamate levels, emphasizing the significance of reliable and continual monitoring in biological systems. Despite their remarkable sensitivity, classical analytical techniques are sometimes compromised by intricate procedures, outrageous expenses, and constrained applicability for point-of-care applications. However, enzymatic electrochemical sensors exhibit higher selectivity; their high production costs and inconsistent functioning make them impractical for long-term use. Nonenzymatic electrochemical sensors, on the other hand, have become a viable alternative due to their superior stability, cost-effectiveness, and ease of manufacture. Recent advancements in nonenzymatic glutamate sensors are thoroughly investigated in this review, with a focus on innovative material strategies that enable enhanced sensitivity, selectivity, and detection limits over a wide concentration range. The aforementioned strategies comprise metal and metal oxide nanostructures, carbon-based platforms, and hybrid composites. It also explores substantial breakthroughs in sensor architecture, operation, and practical applications in intricate biological matrices. These enzyme-free systems' expanding prominence in contemporary biosensing technologies is illustrated by their promise in therapeutic diagnostics, neurochemical research, and point-of-care testing.