ABSTRACT

Dopamine (DA) plays a vital role as a neurotransmitter in the central nervous system (CNS), and its accurate quantification is essential for diagnosing neurological disorders. However, selective and sensitive detection of DA in complex biological matrices remains a challenge due to interference from coexisting biomolecules. In this study, a platinum nanoparticle-decorated carbon nanotubes/polypyrrole-carbon (Pt@CNTs/PPy-C) nanocomposite was synthesized via a facile two-step process involving ultrasonication and photo-reduction, eliminating the need for stabilizers or dispersants. Structural and morphological analysis confirmed the uniform distribution of Pt nanoparticles within the CNTs/PPy-C matrix, enhancing electrocatalytic activity. Electrochemical kinetic studies revealed that DA electro-oxidation on the nanocomposite-modified glassy carbon electrode (GCE) follows adsorption-controlled kinetics, with a transfer coefficient (α) of 0.51 and a heterogeneous rate constant of 8.37 s⁻¹. Differential pulse voltammetry (DPV) demonstrated a high sensitivity of 3.45 µA µM⁻¹ cm⁻² over a linear range of 2.0–24.0 µM with a detection limit of 0.034 µM. The sensor exhibited outstanding selectivity for DA in the presence of various interfering species, along with excellent reproducibility, repeatability and stability. Additionally, the sensor demonstrated high accuracy and reliability in detecting DA in a commercial pharmaceutical formulation, with recovery rates ranging from 96.72% to 101.40%. These findings highlight the potential of the Pt@CNTs/PPy-C nanocomposite as a promising electrocatalyst for DA detection, contributing to the development of highly efficient electrochemical sensors for biomedical and pharmaceutical applications.