A new type of double-stranded DNA targeting format by formation of a Janus-Wedge (J-W) triple helix is described. The "wedge" residue W-1 is used for A-T and T-A base pairs while W-2 is used for G-C and C-G base pairs. Both wedge residues are attached to a PNA backbone that is designed to insert the probe strand into double-stranded DNA and base pair with bothe Watson-Crick faces. To study the stability of such an assembly, we have examined the formation of the J-W triplex with various sequences.