Light driven open/close operation of an azobenzene-modified DNA nano-pincette.

A photoresponsive DNA nano-pincette was constructed by using azobenzene-modified DNA as materials. When the azobenzene-modified part hybridizes with its complementary sequence on the pincette, the duplex formation closes it. On the contrary, the pincette is opened after the formed duplex dissociates. Based on reversible photoswitching of this DNA hybridization, the pincette involving non-substituted azobenzene can be opened simply by UV light irradiation and closed by visible light irradiation. Interestingly, the operation can be reversed by using para-isopropyl group substituted azobenzene: visible light opens the pincette, and UV light closes it. In both cases, the azobenzene-modified part was attached to the pincette throughout the open/close operation, which makes single molecular operation possible. Furthermore, the operation can be repeated many times without any decrease of the cycling efficiency and no DNA waste was produced.