Aptamer-functionalized nanopipettes measure ionic flux through the nanopore at the tip by applying a voltage between two quasi-reference counter electrodes: one inside the nanopipette and one in the measurement solution. The zoom represents a view into the orifice of the nanopipette occluded with aptamers. Upon target binding, the rearrangement of the negatively charged aptamer backbone induces a change in charge distribution within the nanopore. This alteration in charge density influences the ionic flux measured through the nanopore.
