Simultaneous Detection of Dopamine and Serotonin in Real Complex Matrices

Background: Neurotransmitters are chemical messengers with crucial implication in the human body. Perturbations in the concentration of neurotransmitters can affect a multitude of mental and physical functions such as heart rate, sleep, appetite and mood. Thus, the sensitive detection of these compounds is a real need for a new generation of treatments. Methods: Simultaneous detection of two important neurotransmitters, namely dopamine and serotonin, was investigated in this study using differential pulse voltammetry. The optimization of several surface parameters was performed in order to choose the best electrode material for electrochemical oxidation of targets. Screen-printed electrodes based on carbon, gold and platinum and modified with different nanomaterials (carbon nanotubes, gold nanoparticles and carbon nanotubes decorated with gold nanoparticles) were tested. Results: Carbon-based electrodes modified with multiwall carbon nanotubes and gold nanoparticles were chosen after the optimization protocol. Linear correlations between the analytic signals obtained and the concentration of dopamine and serotonin, respectively were obtained with good sensitivity and the detection limits were 0.3 μM for dopamine and 0.8 μM for serotonin with no significant reciprocal influences. Selectivity studies were also performed, as well as tests in real samples (e.g., human serum, tears and saliva) complex matrices for which acceptable recoveries were obtained. Conclusion: The results obtained in this study can be considered as an important starting point for the development of a fast and simple method for selective and highly sensitive detection of neurotransmitters, with possible applications in the diagnosis of different pathologies and for monitoring the effectiveness of the applied drug treatment.