A molecular delivery system by using AFM and nanoneedle.

We developed a new low invasive cell manipulation and gene or molecule transfer system in a single living cell by using an atomic force microscope (AFM) and ultra thin needle, a nanoneedle. DNA was immobilized on the surface of the nanoneedle by covalent bonding and avidin-biotin affinity binding. Immobilization of DNA on the nanoneedle was confirmed by measuring the unbinding force between avidin and biotin. The DNA-immobilized nanoneedle was successfully inserted into HEK293 cells. Though TO-PRO-3 iodide staining experiments using confocal microscopy, we observed the immobilized DNA on the surface of the nanoneedle, which was retained after 10 times insertions to and evacuations from a living cell.