Targeting of parallel c-myc G-quadruplex by dimeric cyanine dye supramolecular assembly: dependence on the linker length.

A series of dimeric cyanine dyes were designed to study their recognition for parallel c-myc G-quadruplex as well as their spectral features in solution. Dimeric cyanine dyes having different length linkers show their recognition for c-myc over duplex DNAs following the order: TC-P4 > TC-P5 > TC-P6 > TC-P3 > TC-P7 [the numeral is the number of repeat units (oligo-oxyethylene) in the linker]. This behaviour might result from their binding with G-quadruplex: the two chromophores of dimers stack on both ends of G-quadruplexes while the linker between two chromophores of dimers binds to the loops and grooves cooperatively. Further, these dyes presented an ability to differentiate the cervical cancer cell (Hela) from the normal cervical epithelial cell (CRL2614). These dyes have promising potential to be sensors to diagnose the G-quadruplex related diseases.