From:  Smart nanofluidic systems powered by DNA origami for targeted intracellular delivery: a newer approach

 Stimuli-responsive mechanisms are employed for intracellular release of therapeutic cargo.

Stimulus typeMolecular triggerMechanism of releaseResponsive DNA origami design elementCellular target environmentReported efficacyReferences
pHAcidic endosomal/lysosomal pH (≤ 6.0)Protonation-induced unfolding of DNA motifs and disruption of gate locksi-motif DNA, pH-labile triplex-forming sequencesTumor cells, endosomes~85% cargo release in acidic vesicles[27]
EnzymeMMP-2, MMP-9, Cas3Cleavage of peptide crosslinks to trigger nanocage openingEnzyme-cleavable linkers integrated in hinge designsTumor stroma, apoptotic environments7× tumor growth suppression vs. control[28]
RedoxHigh intracellular GSH levels (~10 mM cytosol)Disulfide bond reduction causes structural disassemblyDisulfide-modified staple strandsCytosol of cancer cells> 90% release within 30 min in vitro[29]
ThermalMild hyperthermia (42°–45°C)Thermal denaturation of DNA hybrid regions and gate unlockingThermolabile junctions or hairpinsInflamed or laser-targeted tissuesControlled burst release in 10 min[30]
Light (NIR/UV)Photocleavable linkers (e.g., o-nitrobenzyl ester)Light-induced bond cleavage for remote-controlled releaseUV/NIR-responsive chemical gatesSuperficial tumors or optically exposed cellsSpatial release precision < 10 µm[31]
Electric fieldLocalized electric field (> 1 V/cm)Electrophoretic conformational change or gate disruptionCharge-sensitive switches embedded in a DNA scaffoldOn-chip control zones in nanofluidic devicesSub-second release with field application[32]

GSH: glutathione.