Synthesis and Applications of Stimuli-Responsive DNA-Based Nano- and Micro-Sized Capsules

Stimuli-responsive, drug-loaded, DNA-based nano- and micro-capsules attract scientific interest as signal-triggered carriers for controlled drug release. The methods to construct the nano-/micro-capsules involve i) the layer-by-layer deposition of signal-reconfigurable DNA shells on drug-loaded microparticles acting as templates, followed by dissolution of the core templates; ii) the assembly of three-dimensional capsules composed of reconfigurable DNA origami units; and iii) the synthesis of stimuli-responsive drug-loaded capsules stabilized by DNA−polymer hydrogels. Triggers to unlock the nano-/micro-capsules include enzymes, pH, light, aptamer−ligand complexes, and redox agents. The capsules are loaded with fluorescent polymers, metal nanoparticles, proteins or semiconductor quantum dots as drug models, with anti-cancer drugs, e.g., doxorubicin, or with antibodies inhibiting cellular networks or enzymes over-expressed in cancer cells. The mechanisms for unlocking the nano-/micro-capsules and releasing the drugs are discussed, and the applications of the stimuli-responsive nano-/micro-capsules as sense-and-treat systems are addressed. The scientific challenges and future perspectives of nano-capsules and micro-capsules in nanomedicine are highlighted.