(10c) Ultra-Fast Molecule Sorting and Delivery by Atomic Force Microscopy

An AFM is tailored to perform ultrafast electrophoretic differentiation of molecules on populations of <0.1 zeptomoles (10-22 moles) on the surface of a probe tip. The driving force for differentiation is a large electric field applied over the length of an AFM tip that results in enhanced differential mobilities stemming from the confinement of the water layer on the tip surface. In a demonstration on DNA oligonucleotides, a 5-mer and a 16-mer exhibit migration times of 15 and 5 ms, respectively, ~5 orders of magnitude faster than in conventional capillary electrophoresis.