A copper sulfide-hydroxypropyl $\beta$-Cyclodextrin-reduced graphene oxide composite for highly sensitive electrochemical detection of 5-hydroxytryptamine in biological samples

The precise identification of neurotransmitters is essential for comprehending cerebral function, detecting neurological conditions, and formulating successful therapeutic approaches. The present work investigates the electrochemical detection of serotonin with the excellent hybrid electrocatalyst $Cu_2S/H{\beta}cd-rGO$. $Cu_2S$, with its significant features as improved catalytic activity and enhanced charge transfer when combined with $H{\beta}cd-rGO$, will enhance the performance. The integration of $Cu_2S$ with $H{\beta}cd-rGO$, regulated by the van der Waals force and the electrostatic interaction, makes it a stable catalyst without disrupting the composite structure. Also, the aggregation of the $Cu_2S/H{\beta}cd$ with the layered sheets of rGO can be highly reduced and resulting in the improvement of the conductivity. Thus, the above features resulted in the improved oxidation response current when fabricated over the glassy carbon electrode (GCE). The SR showed sensitive response at a broad linear range of 0.019 to 0.299 $\mu$M and 4.28 to 403.14 $\mu$M, resulting in a lower limit of detection (LOD) of 1.2 nM or 0.0012 $\mu$M and a sensitivity of about 15.9 $\mu$A ${\mu}M^{-1}$ $cm^{-2}$. The sensor demonstrated excellent selectivity against common interferents, including aminophenol, dopamine, epinephrine, hydroquinone, melatonin, and chlorine. The real sample studies in the biological samples show good recovery values, showing the effectiveness of the as-fabricated sensor. Thus, the cost-efficient and straightforward integration of $Cu_2S/H{\beta}cd-rGO$ will be an outstanding electrocatalyst for detecting SR.