This review article
introduces mechanistic aspects and applications
of photochemically deprotectedortho-nitrobenzyl
(ONB)-functionalized nucleic acids and their impact on diverse research
fields including DNA nanotechnology and materials chemistry, biological
chemistry, and systems chemistry. Specific topics addressed include
the synthesis of the ONB-modified nucleic acids, the mechanisms involved
in the photochemical deprotection of the ONB units, and the photophysical
and chemical means to tune the irradiation wavelength required for
the photodeprotection process. Principles to activate ONB-caged nanostructures,
ONB-protected DNAzymes and aptamer frameworks are introduced. Specifically,
the use of ONB-protected nucleic acids for the phototriggered spatiotemporal
amplified sensing and imaging of intracellular mRNAs at the single-cell
level are addressed, and control over transcription machineries, protein
translation and spatiotemporal silencing of gene expression by ONB-deprotected
nucleic acids are demonstrated. In addition, photodeprotection of
ONB-modified nucleic acids finds important applications in controlling
material properties and functions. These are introduced by the phototriggered
fusion of ONB nucleic acid functionalized liposomes as models for
cell–cell fusion, the light-stimulated fusion of ONB nucleic
acid functionalized drug-loaded liposomes with cells for therapeutic
applications, and the photolithographic patterning of ONB nucleic
acid-modified interfaces. Particularly, the photolithographic control
of the stiffness of membrane-like interfaces for the guided patterned
growth of cells is realized. Moreover, ONB-functionalized microcapsules
act as light-responsive carriers for the controlled release of drugs,
and ONB-modified DNA origami frameworks act as mechanical devices
or stimuli-responsive containments for the operation of DNA machineries
such as the CRISPR-Cas9 system. The future challenges and potential
applications of photoprotected DNA structures are discussed.