Figure 2.

Schematic illustrating series of events for (1) microsphere-immobilized single-stranded probe incubated with (2) a labeled primary target to form (3) a labeled primary duplex with a center mismatch shown in red. Upon incubation with (4) a longer secondary or competitive target, this competitive target (5) nucleates a secondary duplex by binding to the initially unhybridized toehold segment of the immobilized probe (shown in green) and ultimately proceeds to form (6) an unlabeled, perfectly-matched secondary duplex by (7) displacing the original, shorter primary target. (Reprinted with permission from Hardin and Milam [61] Copyright 2013 American Chemical Society).