Pt-Doped Reduced Graphene Oxide-Porphyrin-CNT Composite-Based Electrochemical Sensor for Simultaneous Detection of Dopamine, Serotonin and Norepinephrine

A novel electrochemical sensor for simultaneous and selective detection of dopamine (DA), serotonin (5-HT), and Norepinephrine (NE) was developed using a platinum-doped reduced graphene oxide-porphyrin-carbon nanotube (Pt-doped rGO-P-CNT) composite. This composite leverages the synergistic effects of its individual components: the aromatic π – π interactions and electrostatic attraction provided by porphyrin-functionalized graphene, the enhanced electron transfer capability from platinum doping, and the high surface area and conductivity of carbon nanotubes. The composite was synthesized in a multi-step process, starting with the oxidation of graphite to produce graphene oxide (GO), followed by reduction of GO and functionalization with porphyrin. Platinum nanoparticles were incorporated using a chemical reduction method, and carbon nanotubes were introduced to further improve conductivity and surface area. Electrochemical characterization demonstrated excellent separation of oxidation peak potentials for DA, 5-HT, and NE, allowing for precise multiplexed detection. The Pt-doped rGO-P-CNT composite showed high electrocatalytic activity and selectivity, with minimal interference from ascorbic acid. The sensor achieved a detection limit as low as 0.012 μM for DA & 5-HT and 0.015 μM for NE. Real-sample analyses in human urine and serum demonstrated the sensor’s practicality, achieving satisfactory recoveries and reproducibility. This Pt-doped rGO-P-CNT composite addresses key limitations in electrochemical biosensing.