Electrochemical Sensing of Neurotransmitters Using a Metal Nanoparticle-Based Composite Platform ^†

Abstract

Neurotransmitters play important roles in the normal functioning of the central nervous system. The accurate and sensitive quantification of neurotransmitters using chromatographic and optical analytical methods is of key interest in the management of related neurodegenerative maladies. In this study, electrochemical sensors based on electrodes modified with composite nanomaterials were investigated as reliable, fast and low-cost analytical devices for direct neurotransmitter quantification. A sensing platform was developed by means of an innovative preparation method using alternating currents (ACs). Low-cost sensing materials based on gold nanoparticles (AuNPs) and poly(3,4-ethylenedioxythiophene) were synthesized in situ onto glassy carbon electrodes by means of AC. A polymeric matrix was prepared by applying an AC at a frequency of 100 mHz for 300 s, resulting in an increase in roughness. AuNPs were synthesized by applying an AC at a frequency of 50 mHz for 100 s. The use of AC enabled the preparation of AuNPs embedded in the polymeric matrix characterized by increased electroactive surface area. The sensing platform was tested and successfully validated in the detection of epinephrine, with good analytical performance, achieving a low detection limit of 0.5 µM and a wide linear response range of 1 to 100 μM epinephrine. The practical applicability of the electrochemical sensing platform was demonstrated in the detection of epinephrine in human serum samples with good accuracy and recovery. AC frequency modulated the electrodeposition process, resulting in enhanced roughness. Consequently, the novel AC-based method ensured an improved sensitivity of the sensing platform compared to other electrochemical epinephrine sensors produced by classical methods, like potentiostatic and galvanostatic ones.