Fabrication of a sensitive neurotransmitter detecting amperometric biosensor employing laccase nanoparticles on a pencil graphite electrode

Abstract

Neurotransmitters including dopamine, adrenaline, and noradrenaline are members of the important class of biogenic amines known as catecholamines. They perform crucial roles in various physiological processes and are frequently associated with stress responses, neurodegenerative and cardiovascular diseases, including Parkinson's and Alzheimer's. This research presents the fabrication of a novel amperometric biosensor designed to detect catecholamine levels with high specificity and sensitivity. The fabrication of the biosensor is based on the immobilization of synthesized cysteine functionalized laccase nanoparticles (Lac-NPs) onto the pencil graphite electrode (PGE). The successful synthesis of Lac-NPs, along with their immobilization and the fabrication of the Lac-NPs/PGE biosensor, was validated through various techniques, including Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectrophotometer (FTIR), UV–visible Spectroscopy, Dynamic Light Scattering (DLS), Zeta potential, Scanning Electron Microscope (SEM), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The biosensor was optimized at various pH, temperature, scan rate and response times to ensure a high-performance sensor with rapid response times and stability for better detection. The Lac-NPs/PGE biosensor showed high sensitivity (2320.0 µA/mM cm²), a lower limit of detection (LOD) (0.12 µM), and a broad linear range (0.1–800.0 µM) with a coefficient of determination of R²= 0.999. In the analysis of real pharmaceutical samples of neurotransmitters, high recovery rates (94.0–99.0 %) have been attained. Superior analytical performance resulting from this simple fabrication process and cost-effective PGE shows this biosensor is a promising tool for the accurate and real-time monitoring of catecholamine levels, with potential applications in clinical diagnostics, neurobiology, and environmental analysis.