Manipulation of DNA origami nanotubes in liquid using programmable tappingmode atomic force microscopy

The nanoscale manipulation of 1D soft and flexible `DNA origami nanotubes´ (DONs) that are 6 nm in diameter and 400 nm in length, and placed on a mica substrate in a TE/Mg²⁺ buffer solution, was executed by an atomic force microscopy (AFM) tip using a programmable tapping-mode manipulation strategy. The AFM´s tip tapping amplitude was controlled to be less than or equal to 10 nm while vibrating in a solution with Mg²⁺ concentration of 10-20 mM. A series of single-point and one-step manipulation experiments revealed that manipulation can be achieved with an 80% successful rate under the condition that the AFM tip vibration amplitude is 3-4 nm and the Mg²⁺ concentration is 10 mM. Utilising this optimised condition, multipoint and multistep manipulation based on the programmable tapping-mode AFM process was conducted and nanomanipulation of DONs was successfully demonstrated.