On the Stability of DNA Origami Nanostructures in Low‐Magnesium Buffers

DNA origami structures have great potential as functional platforms in various biomedical applications. Many applications, however, are incompatible with the high Mg 2+ concentrations commonly believed to be a prerequisite for maintaining DNA origami integrity. Herein, we investigate DNA origami stability in low‐Mg 2+ buffers. DNA origami stability is found to crucially depend on the availability of residual Mg 2+ ions for screening electrostatic repulsion. The presence of EDTA and phosphate ions may thus facilitate DNA origami denaturation by displacing Mg 2+ ions from the DNA backbone and reducing the strength of the Mg 2+ –DNA interaction, respectively. Most remarkably, these buffer dependencies are affected by DNA origami superstructure. However, by rationally selecting buffer components and considering superstructure‐dependent effects, the structural integrity of a given DNA origami nanostructure can be maintained in conventional buffers even at Mg 2+ concentrations in the low‐micromolar range.