P-031

Justina Gaidukevič1,2

justina.gaidukevic@chf.vu.lt

Gintarė Rimkutė1, Rasa Pauliukaitė2

1Faculty of Chemistry and Geosciences, Vilnius University, Lithuania

2Center for Physical Sciences and Technology (FTMC), Lithuania

Exfoliated Graphite-Polythiocyanogen Composites as Potential Materials for Serotonin Sensors

Serotonin (SER) is a neurotransmitter that plays a key role in regulating various complex behaviors, including mood, appetite, sleep, motor function, pain perception, sexual activity, and hormone release. Since maintaining an optimal SER level is essential, its accurate detection has become a critical aspect of clinical diagnostics. Electrochemical sensors have emerged as a promising tool for this purpose, offering benefits such as affordability, user-friendliness, fast response times, high sensitivity, and strong selectivity. However, the effectiveness of these sensors largely depends on the materials used in their construction. Carbon-based materials have demonstrated significant potential for neurotransmitter detection in electrochemical sensors. Among them, exfoliated graphite (EG) has attracted considerable interest due to its advantageous properties, including excellent electrical and thermal conductivity, high mechanical strength, and low density.

The aim of this study was to investigate exfoliated graphite-polythiocyanogen (EG(SCN)n) composites and use them in electrochemical sensors for SER detection. First, three graphite precursors with grain sizes of <50 µm, ≥149 – ≤840 μm, and 2000 µm were intercalated with sulfuric acid and heat-treated at a temperature of 800 °C. The acquired EG samples were modified with conducting polymer polythiocyanogen. The obtained EG(SCN)n samples were characterized structurally using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and were tested as active electrode materials for detecting SER.

SEM micrographs revealed that the layered arrangement observed before modification was replaced by irregularly shaped particles and chaotically arranged individual sheets. XPS confirmed the successful incorporation of nitrogen and sulfur into the graphitic structure. The presence of S–S and C–S bonds suggests that polymer chains could be attached to graphene sheets via sulfur atoms. Electrochemical studies demonstrated that the sensor fabricated with EG(SCN)n_2 sample, obtained from the largest graphite grains, exhibited exceptional sensitivity (1893 µA mM⁻¹ cm⁻²) and a relatively low detection limit of 59.5 nM for the SER analyte.