Catch and release: DNA tweezers that can capture, hold, and release an object under control

A pair of DNA tweezers are constructed, which are capable of capturing, holding and releasing a DNA object by playing with the open and close actions of the tweezers assisted by pH switchings. The object is captured between the tweezers' arms at pH 5.0 through Hoogsteen hydrogen bonding and can be stably held even when the pH is increased to 5.7 after the tweezers are closed. Upon introducing a DNA unlocker strand, the tweezers are opened and the object gets released. This capture-hold-release process can be easily cycled without losing much of its efficiency.