CoCu2O4 Modified Electrodes via Facile Synthesis for Ultrasensitive Dopamine Detection in Physiological Conditions

In this study, we modified a glassy carbon electrode (GCE) with CoCu<inf>2</inf>O<inf>4</inf> nanoparticles (NPs) to create an electrochemical sensor designed for the sensitive and selective detection of dopamine (DA). The CoCu<inf>2</inf>O<inf>4</inf> NPs were synthesized using a solution combustion method, producing porous, loosely packed nanostructures that provide abundant active sites for electrochemical reactions. PXRD coupled with Rietveld refinement confirmed the formation of a single-phase spinel, with a lattice constant of 8.386 Å and an average crystallite size of 18.58 nm. Examination of the surface morphology using SEM revealed porous, agglomerated features, while EDX verified a near-stoichiometric distribution of cobalt, copper, and oxygen within the material. The modified electrode, optimized with a 5 mg CoCu<inf>2</inf>O<inf>4</inf> coating, exhibited a 75 % enhancement in electrochemical response relative to the bare GCE. Operating at physiological pH 7.0, the CoCu<inf>2</inf>O<inf>4</inf> modified GCE exhibited a well-defined redox signal with a linear relationship between DA concentration and current response over 1–8 µM ( R 2 = 0.998). The limit of detection (LOD) was 0.029 ± 0.002 µM, and the limit of quantification (LOQ) was 0.49 ± 0.03 µM, highlighting the sensor’s high sensitivity. Stability assessments indicated 92 % retention of the initial response after one week, and repeatability was confirmed with a relative standard deviation (RSD) of 3.0 %. These findings establish the CoCu<inf>2</inf>O<inf>4</inf> modified GCE as a reliable platform for precise DA quantification, suitable for biomedical and analytical applications.