Assaying biological molecules in body fluids is of paramount importance for the diagnosis and monitoring of numerous human diseases. Various pathological conditions involve dopamine (DA) metabolic disorders in their pathophysiology, rendering the monitoring of dopamine highly significant. This paper reports the development of a biosensor based on laser-induced graphene electrodes (LIGEs) for the analysis of dopamine in urine samples. LIGEs were obtained through direct laser writing of polyimide and subsequently modified with gold nanoparticles (AuNPs), laccase (Lac), and Nafion, which was used to prevent the enzyme desorption from the electrode surface. The electrodes were characterized using cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical investigations demonstrated that the presence of gold nanoparticles and laccase on the electrode surface significantly enhanced the electrochemical performance of LIGEs for dopamine analysis. Under optimal conditions (contact time: 30 s, pH: 7, amount of laccase: 5 mg·mL–1 ), the dynamic range of dopamine concentrations spanned from 0.1 − 50 µM with a detection limit of 0.040 µM. The proposed biosensor was applied to quantify dopamine in urine samples with recoveries ranging from 96 to 98.5%. Consequently, this biosensor represents a cost-effective and promising tool for routine dopamine determination in biological fluids.

Laser writing · Porous graphene · Enzymes · Selectivity · Sensing · Dopamine