DNA’s Shape Shifts When Surrounded by New‑Kind Salts

DNA is not a straight stick; its shape changes with the chemicals around it. Scientists have long known that normal salt can tighten DNA, making it shorter by shielding charges or pulling strands together. Recently, a different group of salts called ionic liquids has been shown to do the opposite: they let DNA stretch out more. In a fresh experiment, researchers attached DNA strands to tiny gold particles and then soaked them in two kinds of ionic liquids—BMIM acetate and EMIM acetate. Using X‑ray scattering, they measured how long the DNA chains became at different liquid concentrations.

They also ran computer simulations that mimicked the real‑world setup to see what was happening at the molecular level. The findings reveal a tug‑of‑war between two forces: electric charges that pull the DNA tight and groove‑binding effects that push it apart. When most of the DNA is single‑stranded, the electric forces win and keep it compact. But as more double‑strand sections appear, a hydrophobic groove‑binding mechanism takes over and causes the DNA to coil in. Thus, the way DNA looks on these gold surfaces depends not just on how much ionic liquid is present, but also on the mix of single and double strands in each chain.

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