Dual-Coreactants Enhanced Electrochemiluminescence

Graphical One plus one is greater than two: A remarkable electrochemiluminescence (ECL) enhancement of Ru(bpy) 3 2+ /TPrA is observed by introducing another coreactant, TEOA, with a 10.8-fold increase of ECL intensity and 1.7-fold extension of ECL layer. The enhancement was interpreted by a chemical oxidation route, in which TEOA + ⋅ acts as an enhancer to produce more TPrA + ⋅ and meanwhile allow the remote formation of TPrA + ⋅. This dual-coreactants strategy works not only in solution with freely diffusive Ru(bpy) 3 2+ but also on Ru(bpy) 3 2+ -functionalized microbeads, showing promise in ECL-based bioassay and microscopy. The electrochemiluminescence (ECL) of ruthenium(II) tris(2,2′-bipyridyl) (Ru(bpy) 3 2+ ) with tri- n -propylamine (TPrA) as the good coreactant can be unexpectedly enhanced by a weak coreactant, such as triethanolamine (TEOA). First, the intensity of ECL emitted by Ru(bpy) 3 2+ /TPrA can be remarkably amplified by 10.8-fold after adding some amount of TEOA. Moreover, the ECL layer thickness, measured by self-interference spectroscopy, is also doubled. The enhancement far exceeding the superposition of respective contribution of TPrA and TEOA was elucidated by a “chemical oxidation mechanism”, in which TEOA + ⋅ acts as a chemical enhancer to oxidize TPrA in solution and to accelerate significantly the ECL reaction kinetics. This mechanism was proved by single-photon counting experiment and finite element simulations. In addition, the dual-coreactants strategy works well not only in solution with freely diffusive Ru(bpy) 3 2+ , but also on Ru(bpy) 3 2+ -functionalized microbeads, suggesting that ethanolamines could act as cheap, easily available and low-background enhancers for ECL-based bioanalysis and microscopy.