Enhancing the Electrochemiluminescence of Luminol by Chemically Modifying the Reaction Microenvironment

As one of the most efficient and commonly used electrochemiluminescence (ECL) reagents, luminol has been paid much attention by the analysts due to its low excitation potential, simple dissolved oxygen-based coreactant ECL reaction requirement, and the widely analytical applications. However, the ECL performances of luminol on most electrode materials suffered from the lower ECL quantum yield, which limited its analytical applications. Herein, it was first found that, compared to that of the bare gold electrode, the ECL quantum yield of luminol on the 1,6-hexanedithiol hydrophobic pinhole film modified gold electrode was 3 times increased. This higher ECL quantum yield of luminol was related to the hydrophobic microenvironment on the surface of the modified electrode, which was formed from the hydrophobic carbon chains on the basis of their supramolecular interaction. On the basis of this new finding as well as the cap effect of gold nanoparticle to these pinhole gates, a highly sensitive ECL sensing scheme for microRNA was also developed.