Spatially Selective Imaging of Cell-Matrix and Cell-Cell Junctions by Electrochemiluminescence.

Cell junctions are protein structures located at different cell membrane domains that determine key processes in multicellular development. Here we report spatially selective imaging of cell junctions by electrochemiluminescence (ECL) microscopy in a label-free manner. By regulating the concentrations of luminophore and/or coreactant, the thickness of ECL layer can be controlled to match with the spatial location of different cell junctions. At a low concentration of luminophore, ECL generation is dominated by the oxidative-reduction route and confined to the electrode surface, thus revealing only cell-matrix adhesions located at the bottom surface of cells. While at a high concentration of luminophore, the catalytic route is involved and the ECL layer can be remarkably extended away from the electrode surface by decreasing the coreactant concentration, thus allowing the sequential imaging of cell-matrix and cell-cell junctions at the bottom and near the apical surface of cells, respectively. This strategy not only provides new insights into the mechanism of ECL generation but also promises wide applications of ECL microscopy in bioimaging.