Nanodissection, isolation, and PCR amplification of single DNA molecules

A unique technique for positioning, dissection, and isolation of single DNA molecules using atomic force microscopy (AFM) has been demonstrated. Full-length genome DNA molecules were first deposited and stretched by a modified 'Molecular Combing' technique on a 3-aminopropyl triethoxysilane-coated mica substrate. A single DNA fragment was dissected from individual genome DNA strands with the AFM tip at the desired position, and then isolated (or picked up) after a special operation called 'kneading'. All the operations including imaging, dissection, and isolation could be carried out with one tip. The isolated DNA fragment on the AFM tip could be successfully amplified by single-molecule PCR. Some of the physical and chemical mechanisms are discussed.