Kraft-Based Femtosecond Laser-Induced Graphene for Electrochemical Dopamine Sensing

In this work, laser-induced graphene from kraft paper (kraft paper-LIG) was employed for the nonenzymatic electrochemical sensing of dopamine (DA). We reported the fabrication and characterization of a disposable, cost-effective, kraft-based electrochemical dopamine sensor with the sensing electrode consisting of laser-induced graphene derived from kraft paper. Kraft paper-LIG was formed by the femtosecond laser modification of kraft paper into a three-dimensional (3D) graphene arrangement. Our study labeled that the electrochemical activity of kraft paper-LIG can be improved via a dual pass (defocused, followed by focused lasing). Kinetic analysis showed that the effective heterogeneous electron transfer rate constant of kraft paper-LIG was 2.8 × 10^-3 cm s^-1 using Fe(CN)₆^3-/4- as a redox probe. The kraft paper-LIG electrodes successfully detected and quantified dopamine in phosphate-buffered solution (PBS) within the 1-100 μM range. A linear response (R² = 0.9986) was observed, with a sensitivity of 37.381 μA cm^-2 μM^-1. Furthermore, the kraft paper-LIG electrodes denoted sufficient selectivity for DA in electrolytes containing ascorbic acid (AA) and uric acid (UA). Kraft paper-LIG electrodes also had good stability at ordinary temperature.