Self-assembly of DNA nanostructures in different cations.

The programmable nature of DNA allows the construction of custom-designed static and dynamic nanostructures, and assembly conditions typically require high concentrations of magnesium ions which restricts their applications. In other solution conditions tested for DNA nanostructure assembly, only a limited set of divalent and monovalent ions have been used so far (typically Mg 2+ and Na + ). Here, we investigate the assembly of DNA nanostructures in a wide variety of ions using nanostructures of different sizes: a double-crossover motif (76 bp), a three-point-star motif (∼134 bp), a DNA tetrahedron (534 bp) and a DNA origami triangle (7221 bp). We show successful assembly of a majority of these structures in Ca 2+ , Ba 2+ , Na + , K + and Li + and provide quantified assembly yields using gel electrophoresis and visual confirmation of a DNA origami triangle using atomic force microscopy. We further show that structures assembled in monovalent ions (Na + , K + and Li + ) exhibit up to a 10-fold higher nuclease resistance compared to those assembled in divalent ions (Mg 2+ , Ca 2+ and Ba 2+ ). Our work presents new assembly conditions for a wide range of DNA nanostructures with enhanced biostability.