Determination of Dopamine in the Presence of Uric Acid and Folic Acid by Carbon Paste Electrode Modified with CuO Nanoparticles/Hemoglobin and Multi-Walled Carbon Nanotube

This work describes the development of a novel biosensor for determination of dopamine) DA) in the presence of H 2 O 2 and folic acid, and uric acid as interferences. The biosensor was fabricated from a carbon paste electrode modified with electrostatically immobilized hemoglobin (Hb) on copper oxide (CuO) nanoparticles and multi-walled carbon nanotubes. Because some phenolic compound biosensors were developed using the peroxidase properties of hemoglobin, this cane cause the reduction of phenolics in the presence of H 2 O 2 . However, the presence of hemoglobin in this electrode led to catalytic oxidation of DA at the electrode surface in the presence of H 2 O 2 . The biosensor's performance for phenolic compound detection depends on Hb acting as an electron mediator. This biosensor presents a sensitive response for DA. The parameters of the electrode fabrication with experimental conditions for Hb immobilization on CuO nanoparticles were optimized. Linearity for the detection of the DA was observed from 5 μM to 1 mM. Its detection limit was calculated at ∼20 nM. Electrode response reached 80% of its primary response after 30 days. The response time of the developed electrode was about 10 seconds.