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.
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