Electrocatalytic Generation of Cathodic Luminol Electrochemiluminescence with Carbonized Polydopamine Nanotubes at a Low Positive Potential

The generation of luminol electrochemiluminescence (ECL) is easily disrupted by the unexpected reactive oxygen species (ROS) involved in the complicated reaction processes. Herein, we describe the preparation of carbonized polydopamine nanotubes (C-DPANTs) and their usefulness in the development of a new ECL biosensor with a high anti-interference capacity. C-PDANTs with pyridinic N and graphitic N compositions were found to accelerate the electron transfer and improve onset potential, serving as electrocatalysts to enhance both cathodic and anodic luminol ECL. Moreover, the onset potential of H2O2 reduction was improved up to similar to 0.2 V on a C-PDANT-modified glassy carbon electrode (C-PDANTs-GCE), allowing the efficient generation of cathodic ECL of the luminol/H2O2 system in a positive potential and significantly reducing the interference caused by O-2. Finally, by integrating cholesterol oxidase (ChOx) with C-PDANTs, an ECL biosensor was developed based on C-PDANTs(a)ChOx-GCE and the luminol/H2O2 system. The proposed ECL biosensor was demonstrated in the sensitive and selective detection of cholesterol with a linear range of 8.0 to 1.2 x 10(3) mu M and a detection limit of 4.2 mu M.