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.