Functionalized MWCNT decorated bismuth molybdenum sulfide electrode for sensitive and selective melatonin detection in dietary components: DFT insights

Melatonin is a crucial hormone that regulates sleep cycles, the biological clock and the body's antioxidant defences. Sleep issues, neurodegenerative illnesses and metabolic disorders are linked to melatonin concentration abnormalities. Electrochemical sensors that can detect it precisely, quickly and sensitively. The 5% Functionalized multi walled carbon nanotube doped bismuth molybdenum sulfide nanocomposite (5% f-MWCNT@BMS) was synthesized using a hydrothermal approach and employed for the sensitive electrochemical detection of melatonin. The formation of the nanocomposite was verified by XRD, FE-SEM, EDX and XPS analysis. The incorporation of 5% f-MWCNT reduced the charge transfer resistance from 163.7 Ω to 50.19 Ω, where the surface area increased from 0.04 to 0.13 cm 2 . The sensor exhibited a linear response from 1 to 70 µM, a detection limit of 0.106 µM and a sensitivity of 3.676 µA µM −1 cm 2 . The developed electrode showed high selectivity, excellent repeatability with RSD of 0.45%, good long-term stability and reliable performance in real sample analysis. The practical applicability of the sensor was validated in milk, apple and tomato samples, achieving recovery values of 94.21–105.63%, respectively. These results demonstrate that the 5% f-MWCNT@BMS nanocomposite is an effective electrode material for rapid and sensitive electrochemical determination of melatonin.