Programmable in vitro and in vivo folding of single-stranded nucleic-acid wireframe origami

As a latecomer in DNA/RNA nanotechnology, the architecture of self- folded nucleic-acid nanostructures has been attracting increasing research interests because of its vast potential for in vivo applications. With the implementation of branched kissing-loop junctions, we developed a robust and generic design platform to construct single- stranded origami (ssOrigami) wireframe structures. The designated multistage folding pathway led to the production of a variety of ssOrigami constructs. Incorporating functional nucleic-acid elements into ssOrigami design, we further created constructs with their activities dictated by the prescribed molecular assembly. More importantly, we demonstrated the in vivo production and in situ folding of single-stranded RNA constructs with intrinsic fluorescent activity in human cells.