Reversible photocycloaddition of 8-pyrenylvinylguanine for photoreactive serinol nucleic acid (SNA).

Photoresponsive nanomachines are attractive components of functional nanodevices and nanosystems. To develop new photoresponsive nucleic acid-based nanomachines, we conjugated 8-pyrenylvinylguanine (PVG) to a serinol linker and incorporated it into an acyclic xeno nucleic acid, serinol nucleic acid (SNA). The two PVG residues incorporated into SNA underwent interstrand photocycloaddition upon 447 nm light irradiation in the duplex state, whereas previously reported 8-pyrenylvinyladenine (PVA) formed both intrastrand and interstrand photodimers. The PVG photodimer was converted to monomers by irradiation with 350 nm light. This photoreaction enabled reversible photoregulation of the formation and dissociation of the SNA/RNA duplex, although some byproducts were generated due to the slower photoreaction of PVGs than that of PVAs. In contrast, when a single PVG was incorporated into SNA, the interstrand photocycloaddition and cycloreversion were remarkably fast and effective in the single-stranded state. We utilized this to demonstrate a photocaging system that achieves one-way photoswitching of hybridization ability. The powerful photocycloaddition properties of PVG-SNA are expected to find applications in new photoresponsive nanodevices and nanosystems.