Modification of boron-doped diamond electrode with polyaniline and gold particles to enhance the electrochemiluminescence of luminol for the detection of reactive oxygen species (hydrogen peroxide and hypochlorite)

A luminol electrochemiluminescence (ECL)-based sensor for reactive oxygen species (ROS), including H₂O₂ and hypochlorite was developed using gold particles-modified on polyaniline‑boron doped diamond electrode (Au-PANI/BDD). The gold particles were incorporated onto the surface of boron-doped diamond (BDD) electrode to enhance the electrochemiluminescence of luminol, while the polyaniline was used to provide better attachment of the gold particles on the surface of BDD electrode. The uniform distribution of gold particles on the PANI/BDD surface was verified through FE-SEM EDX analysis with an approximately weight percentage of 45.6 % (w/w). The modified electrode exhibited a remarkable five-fold increase in ECL intensity compared to the unmodified BDD, resulting in higher sensitivity. Furthermore, the sensor's performance was successfully demonstrated for H₂O₂ concentrations ranged linearly from 1 to 100 μM (R² ≥ 0.99) with a low detection limit of 0.81 μM, and for hypochlorite concentrations from 1 to 20 μM (R² ≥ 0.99) with a detection limit as low as 0.51 μM. Additionally, excellent repeatability and stability of the signals was also observed over 7 days. Furthermore, successful application in detecting H₂O₂ and hypochlorite in real sample highlights its promising potential as an ROS sensor.