Heteroatom-doped reduced graphene oxide electrochemical sensor for sensitive dopamine detection with preliminary clinical evaluation of neurotransmitter dysregulation in pediatric epilepsy

Abstract

Monitoring dopamine (DA) levels in biological fluids is highly informative for the early diagnosis and therapeutic management of neurological disorders such as Parkinson's disease, schizophrenia, attention-deficit/hyperactivity disorder (ADHD), and epilepsy, which represents a major pediatric neurological condition with wide clinical heterogeneity. In this study, we report a preliminary clinical evaluation of an electrochemical sensor developed for DA detection in the blood of pediatric epilepsy patients. The sensing platform is based on screen-printed carbon electrodes (SPCEs) modified with nitrogen-doped reduced graphene oxide (N-RGO) and nitrogen/sulfur co-doped reduced graphene oxide (S/N-RGO) to enhance electrocatalytic performance. Heteroatom incorporation into RGO significantly improved electron transfer kinetics, electroactive surface area, and sensing activity. Using chronoamperometry (CA) and differential pulse voltammetry (DPV), the N-RGO sensor achieved low detection limits of 6.8 nM and 7.9 nM, respectively, in buffer, with excellent selectivity in the presence of common interferents such as ascorbic acid and uric acid. High recovery rates (∼100%) were obtained in commercial plasma and fresh human serum samples, including those collected from pediatric epilepsy patients. Notably, DA plasma concentrations were found to be lower in this heterogeneous group of epileptic patients, reflecting neurotransmitter dysregulation associated with epilepsy subtype and antiepileptic treatment (valproate). This work presents a sensitive electrochemical sensor capable of detecting and monitoring DA in blood and highlights its potential as a minimally invasive point-of-care tool for pediatric epileptic patients. With further development, this device could also be applied to assess DA levels in other neurological disorders.