A study of screen-printed electrodes modified with MoSe2 and AuNPs-MoSe2 nanosheets for dopamine sensing

Molybdenum selenide nanosheets (MoSe2-NS) were synthesized by liquid-phase exfoliation (LPE) technique and successive liquid cascade centrifugation (LCC) at two different centrifugation rates (1.5 and 5 krpm). By this technique's combination, we were able to prepare MoSe2 nanosheets with different geometric characteristics (i.e., average number of layers and average lateral length ). Increasing the centrifugation speed from 1.5 krpm to 5 krpm leads to a decrease in number of layers (down to nL = 2 – 4, with the presence of sparse monolayer flakes) and average lateral size of NS from 280 nm to 180 nm, as confirmed combining optical and morphological analysis. Modified screen-printed carbon electrodes (SPCE) with the as prepared MoSe2-NS were fabricated and applied for the determination of dopamine (DA) as an electroactive model analyte in the concentration ranging from 0.5 to 80 µM. DA is an important neurotransmitter for human beings and its deficiency can bring out various health diseases like Parkinson's and brain disorders, thus the development of simple DA sensors is highly demanding. Results demonstrated the better performances of the modified MoSe2 (5 krpm)/SPCE sensor compared to bare SPCE and the MoSe2 (1.5 krpm)/SPCE. With the objective to improve the electroanalytical performances toward dopamine, AuNPs-MoSe2-NS hybrid composite was also prepared, mixing AuNPs obtained by a green-reduction method with the MoSe2-NS. The developed AuNPs-MoSe2 (5 krpm)/SPCE sensor resulted the most promising with further improved sensitivity as compared to MoSe2/SPCE.