Photocontrol of duplex formation between the totally artificial serinol nucleic acid (SNA) and target RNA was made possible using a photoresponsive nucleobase 8-pyrenylvinyl adenine (PVA). PVA residues in SNA can be induced to undergo intrastrand [2 + 2] photocycloaddition by 455 nm light. Effective cycloreversion of the PVA photodimer results from irradiation with 340 nm light. These reactions occurred in high yield, rapidly, selectively, and reversibly. When the PVA-SNA/RNA duplex was irradiated with 455 nm light, almost complete dissociation of the duplex was attained, and 340 nm light restored duplex formation by cycloreversion. This is the first example of use of photocycloaddition and cycloreversion to photoregulate canonical duplex formation and dissociation reversibly at constant temperature. Thus, SNA bearing PVA residues have potential for use in photocontrollable biological tools targeting endogenous RNAs in cells as well as photodriven SNA machines.

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Wavelength‐selective photo‐regulation by multiple chromophores responding to different wavelengths can expand the variation of photo‐manipulating systems. Herein, we report the orthogonal photo‐regulation of duplex formation between serinol nucleic acid (SNA) and RNA using light‐induced crosslinking reactions mediated by a new photo‐reactive nucleobase 8‐naphthylvinyladenine (NVA) and previously described 8‐pyrenylvinyladenine (PVA). An intrastrand crosslink was induced in an SNA strand containing two adjacent NVA residues by irradiation with 340–405 nm light; the crosslink was reversed by irradiation with ≤300 nm light. In an SNA strand with adjacent NVA and PVA residues, an intrastrand crosslink resulted from irradiation with 405–465 nm light that was reversed by irradiation with ≤340 nm light. Intrastrand photo‐crosslinking caused severe destabilization of an SNA/RNA duplex, resulting in dissociation to single strands. Cycloreversion resulted in duplex formation. With these NVA/NVA and NVA/PVA photo‐switches, four hybridization states of two SNA/RNA duplexes could be orthogonally photo‐controlled by irradiation with a suitable wavelength of light.

The interstrand crosslinking and threaded structures of nucleic acids have high potential in oligonucleotide therapeutics, chemical biology, and nanotechnology. For example, properly designed crosslinking structures provide high activity and nuclease...

The formation of interlocked structures, such as rotaxane and catenane, enables noncovalent conjugations. We previously confirmed that the chemically cyclized pseudorotaxane-forming oligodeoxynucleotides (prfODNs) with double-tailed parts formed a pseudorotaxane structure with the target DNA and RNA via the slipping process. Here, we report the one-step synthesis of cyclized prfODNs from alkyne-modified ODNs, after which we investigated the properties and mechanism of the slipping process and performed noncovalent RNA labeling with prfODNs. Additionally, the catenane structure was formed by the combination of pseudorotaxane formation with a 5′-end-phosphorylated RNA and enzymatic ligation. The newly synthesized prfODN represents a new tool for achieving the noncovalent conjugation of various functional moieties to RNAs.