Aptamers as potential tools for super-resolution microscopy

(a) The TfnR aptamer c2, the EGFR aptamer E07 and their respective control aptamers (random sequences) were incubated at 37°C with human A431 cells as described in Supplementary Methods. Similarly, HeLa cells stably transfected with a human PSMA construct were incubated with the PSMA A9 aptamer or its random control. The pairs of images (control and aptamer) are equally scaled to allow a direct visual comparison. The insets in the control images correspond to the same images, scaled to a level where autofluorescence can be visualized. Scale bar, 10 μm. (b) Colocalization of the different aptamers with endosomal labels. We co-incubated the cells (same as above) with aptamers against TfnR (c2) or PSMA (A9) and Alexa488-transferrin (Invitrogen), since the latter constitutes an ideal marker for early endosomes.