Synergistic TiO2@C composite for enhanced simultaneous electrochemical detection of dopamine and uric acid in human urine

The electrooxidation of dopamine (DA) and uric acid (UA) suffers from significant signal overlapping due to their similar oxidative potentials. In this study, a composite material consisting of carbon film coating on the surface of anatase TiO 2 (TiO 2 @C) is proposed for the simultaneous detection of DA and UA. The synergistic effect of TiO 2 @C, which includes enhanced charge transfer efficiency and improved conductivity, significantly promotes the electrooxidation process. TiO 2 @C is prepared via a simple calcination approach by annealing MIL-125 at 750 °C under a nitrogen atmosphere. Systematic material characterization, including x-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy, etc., is performed to confirm the structural properties and surface composition of TiO 2 @C. TiO 2 @C is then used to modify a glassy carbon electrode (GCE) via drop-coating. A series of electrochemical measurements are conducted for the detection of DA and UA. After optimizing the measurement procedure, simultaneous detection of DA and UA is achieved, with linear ranges of 0.2 to 200 μM for DA and 0.2 to 40 μM for UA, and detection limits of 0.11 μM for DA and 0.09 μM for UA (D = 3σ/k). Further evaluations, including anti-interference testing, stability, and reusability, provide a comprehensive understanding of TiO 2 @C’s performance. Finally, the TiO 2 @C/GCE is applied to determine DA and UA in human urine samples, yielding recoveries between 100.19–101.87 % for DA, and 93.09 %–105.30 % for UA. This study highlights the synergistic effect of TiO 2 @C in electrode modification, demonstrating its potential for the sensitive and selective electrochemical detection of DA and UA.