Near-Infrared Electrochemiluminescence from Au Nanoclusters Enhanced by EDTA and Modulated by Ions

Near-infrared electrochemiluminescence (ECL) from Au-thiolate nanoclusters is activated by electrode reactions and enhanced by ethylenediamine tetraacetic acid (EDTA). The enhancement effect is higher at pH 7.4 than at more basic or acidic pHs. Magnesium ions are found to modulate the ECL signals through complexation with EDTA and the interaction with the Au nanoclusters. The chemical system and the signal modulation mechanism are believed to be generalizable and advantageous for future sensing and analysis applications with the following merits: 1) Ambient ECL without oxygen removal, 2) high enhancement at physiological pH values, 3) in the near-IR spectrum window with low interference, 4) rich and tunable redox activity of the Au nanoclusters, and 5) EDTA representing other ionophores or chelaters as versatile coreactants.