Electrochemical Biosensing Platform for Rapid Detection of Neurotransmitters

Neurotransmitters such as dopamine, serotonin, and epinephrine are critical regulators of neurological and physiological functions. Dopamine, a catecholamine neurotransmitter, plays a key role in movement, reward, and cognition. Imbalances in dopamine levels are linked to disorders including Parkinson’s and Alzheimer’s disease. Conventional detection methods such as liquid chromatography–mass spectrometry (LC/MS), while sensitive, are costly, time-consuming and unsuitable for point-of-care use. This underscores the need for rapid and sensitive monitoring of different neurotransmitters in biological fluids for early diagnosis and disease management.

Functionalized electrochemical biosensors based on screen-printed carbon electrodes (SPCEs) offer a low-cost alternative capable of real-time biomolecule detection. In this study, we modified SPCEs with a novel hybrid composite of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), reduced graphene oxide (rGO), and gold nanoparticles (AuNPs) for the rapid and sensitive detection of neurotransmitters, including dopamine. rGO increases electroactive area and electron transfer kinetics, PEDOT:PSS improves conductivity and sensor durability, and AuNPs enhance the electrochemical signal.

Electrochemical characterization with a potassium ferricyanide solution confirmed that the biosensor exhibited higher peak currents and lower charge-transfer resistance than unmodified SPCEs. We subsequently employed our biosensor for dopamine detection using square wave voltammetry (SWV). Dopamine undergoes oxidation to dopamine-o-quinone, generating a measurable anodic current proportional to concentration. Calibration experiments from 50 nM to 500 μM revealed a linear response, with a detection limit of ~100 nM, below typical dopamine levels reported in saliva and urine. These preliminary findings demonstrate the potential of our biosensor for non-invasive dopamine monitoring and future multiplexed neurotransmitter detection.