A Signal Amplification Strategy Using ATP as a Co-Reaction Accelerator for the Electrochemiluminescence of Ru(bpy)32+/HEPES System and Detection of Iodide Anions**

Graphical In the study, Ru(bpy) 3 2+ was used as the luminophore, HEPES buffer was served as the co-reactant, and ATP was added to the system to amplify the luminous signal. It was speculated that ATP acts as an co-reaction accelerator to promote the oxidation of HEPES to HEPES + ⋅, more HEPES⋅ can be generated, which then reacts with oxidized Ru(bpy) 3 3+ to emit stronger ECL signals. Moreover, I - consumes ATP, Ru(bpy) 3 2+ , and HEPES, leading to a decrease in ECL signal. Adenosine triphosphate is an important biological molecule that provides energy and substrate for various cellular biochemical processes,it's ubiquitous in our lives. In this work, a novel electrochemiluminescence (ECL) sensor composed of Ru(bpy) 3 2+ , 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid (HEPES) and adenosine 5’-triphosphate disodium salt (ATP) was developed for the first time. In this ECL system, Ru(bpy) 3 2+ was used as the luminophore, HEPES buffer was served as the co-reactant, and ATP was added to the system to amplify the luminous signal to investigate the ECL behavior. Through fluorescence spectroscopy, ECL spectroscopy, and cyclic voltammetry (CV), it can be hypothesized that the possible ECL mechanism is that ATP acts as an advanced co-reaction promoter to accelerate the oxidation of HEPES to HEPES + ⋅, more HEPES⋅ can be generated, which then reacts with oxidized Ru(bpy) 3 3+ to emit stronger ECL signals. Subsequently, the influence of the ATP concentrations and the CV scanning speed was investaged. Moreover, it was observed that I − could quench the ECL intensity, the linear relationship range of I − concentration is from 10 −3 to 10 −6 m , the limit of detection is 3.7×10 −8 m (signal/noise=3), therefore, a new, highly sensitive, and selective ECL approach for I − detection was created.