Cation-responsive and photocleavable hydrogels from non-canonical amphiphilic DNA nanostructures

Thanks to its biocompatibility, versatility and programmable interactions, DNA has been proposed as a building block for functional, stimuli-responsive frameworks with applications in biosensing, tissue engineering and drug delivery. Of particular importance for in vivo applications is the possibility of making such nano-materials responsive to physiological stimuli. Here we demonstrate how combining noncanonical DNA G-quadruplex (G4) structures with amphiphilic DNA constructs yields nanostructures, which we termed "Quad-Stars", capable of assembling into responsive hydrogel particles via a straightforward, enzyme-free, one-pot reaction. The embedded G4 structures allow one to trigger and control the assembly/disassembly in a reversible fashion by adding or removing K+ ions. Furthermore, the hydrogel aggregates can be photodisassembled upon near-UV irradiation in the presence of a porphyrin photosensitiser. The combined reversibility of assembly, responsiveness and cargo-loading capabilities of the hydrophobic moieties make Quad-Stars a promising candidate for biosensors and responsive drug delivery carriers.