Existing and Emerging Point-of-care Devices for Neurotransmitter Detection

Neurotransmitters are the vital endogenic biochemicals responsible for the human body's daily functions and these are achieved through communication between neurons throughout the human physiological system. Neurons enable the human brain to perform various functions via chemical synaptic transmission. Generally, the synaptic transmission between the presynaptic neural cell and the postsynaptic receptors is accomplished through the significant release of neurotransmitters into the medium. In addition, neurotransmitters are effectively engaged in the development process of humans, enabling the growth of neurons, differentiation, and the development of neural circuitry. Thereby, even a trivial change in levels of specific neurotransmitters in human biological fluids is recognized as an effective diagnostic signal for various neurological disorders and diseases, such as Parkinson's disease, schizophrenia, depression, and Alzheimer's disease. On the other hand, neurotransmitters are reported as biomarkers for different diseases and disorders as they are engaged in different stages of human development. Detecting neurotransmitters facilitates the early diagnosis of many neurological diseases or disorders. However, their trace level concentrations along with the existence of other minerals and biochemical molecules limits and complicates the detection mechanism and reduces the efficacy of point-of-care (POC) devices. In the past few decades, a substantial development in POC device technology has been reported, with good selectivity and sensitivity, for early diagnosis of several neurological diseases and disorders. This chapter will discuss neurotransmitter detection for existing and emerging point-of-care devices for effective diagnosis of neurological disorders involving different analytical techniques, such as electrochemical sensing, spectral-based analytical techniques (like surface-enhanced Raman scattering, SERS), and spectroscopy. This chapter aims to elucidate the pros and cons of different analytical techniques and provide clear insight into the scope for development of POC devices for diagnostic applications.