How could ionic interactions be used in DNA-RNA hybridisation?

The DNA double helix consists of many hydrogen bonds between the base pairs, but in addition there are negatively charged phosphate molecules as a key component of the sugar-phosphate backbone of DNA strands. In order to induce the hybridisation between a single stranded DNA molecule and a complementary single RNA strand, the double helix must be separated. This is done by introducing ions such as Na+ and Mg2+; as these are positively charged ions, they will interact and partially counteract the phosphates negative charge. Having these ions present in a water solution, will also allow the hydrogen bonds between the bases to be temporarily relocated to having formed hydrogen bonds with the water solution.