Figure 8.

Schematic representation of the most common modes PNA-based probes hybridise with dsDNA: (A) Fluorescent PNA probes (green) can be designed to directly label dsDNA by forming a triple helical structure (triplex); (B) As in A., but by double duplex invasion; or (C) by duplex invasion, among other binding modes. Alternatively, as duplex invasion (C) leads to strand displacement, a PNA opener can make hybridization sites available for secondary probes without sample denaturation or a fixation step.