Molecular crowding of the cosolutes induces an intramolecular i-motif structure of triplet repeat DNA oligomers at neutral pH.

We now present the first example in which triplet repeat DNAs adopt the i-motif structure at neutral pH by molecular crowding. Crowding stabilized the i-motif and the pK(a) of N3 of cytosine was raised in such a microenvironment. Molecular crowding is known to accelerate the formation of the multi-stranded i-motif while the triplet repeats adopt the single-strand structure.