Electrogenerated Chemiluminescence in Submicrometer Wells for Very High-Density Biosensing

Inspired by the mechanism in stimulated emission depletion fluorescence microscopy, we established for the first time electrogenerated chemiluminescence (ECL) generated from indium tin oxide (ITO) submicrometer electrodes in submicrometer wells with aluminum walls. Aluminum is observed to have the ability to absorb ECL from luminol and, thus, removes the ECL from the diffused species away from the electrode surfaces. Accordingly, the size of the individual ECL spots is restricted to 4 μm in diameter, enabling the density of the ECL based array to be over 3 × 10⁴/mm². The conceptual detection of hydrogen peroxide and glucose exhibits the feasibility in the application of luminol ECL for very high-density biosensing. The realization of this ECL in submicrometer wells and the resultant biosensing offer a new strategy for high-density ECL analysis and might initiate the thought for super-resolution ECL microscopy.