Enhanced electrocatalytic detection of dopamine via InZnSe@CeAu quantum dots-reduced graphene oxide nanocomposite

Dopamine (DA) is a central neurotransmitter whose dysregulation is linked to neurological disorders. Thus, there is a need for rapid and reliable quantification of DA in complex biological media. Here we report on the development of a hierarchical electrochemical platform based on InZnSe@CeAu–SiO 2 quantum dots (QDs) integrated with reduced graphene oxide (rGO), to form a nanocomposite system with enhanced surface area, conductivity and interfacial charge transfer. Comprehensive structural, optical, and electrochemical characterisation confirmed the successful formation of a stable and highly conductive nanocomposite system. When immobilised on glassy carbon electrodes, the InZnSe@CeAu–SiO 2 -rGO nanocomposite enabled multi-mode detection of DA using square-wave voltammetry (SWV), amperometry and step-wise amperometry. The assay system exhibited wide dynamic ranges (SWV: 5–1000 μM; amperometry: 25–1000 μM; step-wise amperometry: 10–1000 μM) with respective limits of detection of 5.0 μM, 3.75 μM, and 8.01 μM. Beyond sensitivity, the detection platform demonstrated robust reproducibility, operational stability over 10 days and resilience against ionic interference. Importantly, it enabled simultaneous discrimination of DA, paracetamol and caffeine, and achieved accurate quantification in 100 % human serum with recoveries ≥93.8 %. These developments established InZnSe@CeAu–SiO2-rGO nanocomposite as a versatile and powerful electrocatalytic transducers for neurotransmitter biosensing with strong translational potential. • Cadmium free InZnSe@CeAu coated with SiO 2 integrated with rGO for dopamine sensing. • Multi mode detection by square wave voltammetry, amperometry and stepwise amperometry with wide ranges and low limits. • Simultaneous measurement of dopamine, paracetamol and caffeine with well separated peaks. • Strong reproducibility, ten day stability and tolerance to common ions. • Accurate quantification in undiluted human serum with acceptable recoveries.