Mitoxantrone and Analogues Bind and Stabilize i-Motif Forming DNA Sequences.

There are hundreds of ligands which can interact with G-quadruplex DNA, yet very few which target i-motif. To appreciate an understanding between the dynamics between these structures and how they can be affected by intervention with small molecule ligands, more i-motif binding compounds are required. Herein we describe how the drug mitoxantrone can bind, induce folding of and stabilise i-motif forming DNA sequences, even at physiological pH.

Reversible DNA i-motif to hairpin switching induced by copper(II) cations.

i-Motif DNA structures have previously been utilised for many different nanotechnological applications, but all have used changes in pH to fold the DNA. Herein we describe how copper(II) cations can alter the conformation of i-motif DNA into an alternative hairpin structure which is reversible by chelation with EDTA.

i-Motif DNA: structure, stability and targeting with ligands.

i-Motifs are four-stranded DNA secondary structures which can form in sequences rich in cytosine. Stabilised by acidic conditions, they are comprised of two parallel-stranded DNA duplexes held together in an antiparallel orientation by intercalated, cytosine-cytosine(+) base pairs. By virtue of their pH dependent folding, i-motif forming DNA sequences have been used extensively as pH switches for applications in nanotechnology.

Silver cations fold i-motif at neutral pH.

i-Motif DNA structures have previously been utilised for many different nanotechnological applications, but all have used acidic conditions to fold the DNA. Herein we describe the use of silver cations to fold an i-motif forming DNA sequence at physiological pH. Subsequent DNA unfolding can be achieved by chelation with cysteine.

(E,E)-1,5-Cyclooctadiene: a small and fast click-chemistry multitalent.

Two in one--We show here that the highly strained trans,trans-diolefin (E,E)-1,5-cyclooctadiene can perform efficiently two different click reactions at fast reaction rates. It is capable of first undergoing [3+2] cycloadditions with 1,3-dipoles at a reaction rate comparable to that of strained cyclooctynes. The resulting cycloadduct can then perform a much faster inverse-electron-demand Diels-Alder reaction with tetrazines, effectively linking an azide to a tetrazine.