Figure 1.

(A) Working principle of an MB. In the absence of a DNA target, the MB is in its closed hairpin state, and fluorescence is quenched due to close proximity of fluorophore and quencher (left). Upon target binding to the loop region, the hairpin stem melts and fluorescence is emitted as a consequence of the increased distance of fluorophore and quencher; (B) chemical structure of homo-DNA; (C) structure of the reversed Hoogsteen A–A base pair in homo-DNA duplexes.