Recognition imaging with a DNA aptamer

We have used a DNA-aptamer tethered to an atomic force microscope probe to carry out recognition imaging of IgE molecules attached to a mica substrate. The recognition was efficient (similar to 90%) and specific, being blocked by injection of IgE molecules in solution, and not being interfered with by high concentrations of a second protein. The signal/noise ratio of the recognition signal was better than that obtained with antibodies, despite the fact that the average force required to break the aptamer-protein bonds was somewhat smaller.