Cationic perylenediimide as a specific fluorescent binder to mismatch containing DNA

Small ligand molecules, which can recognize thermodynamically unstable site within DNA, such as mismatch base pair, abasic site, and single-bulge, have attracted much attention because of their potential diagnostics and biological applications. In this paper, we describe the binding of cationic perylenediimide (cPDI) molecules to thymine-containing mismatch base pair in DNA and the formation of cPDI dimer at the mismatch site. The cPDI dimer exhibits a characteristic excimer emission at 650nm. For T/T mismatch containing DNA, the switching behavior from the PDI dimer (650nm) to the monomer (550nm) emission in specific response to Hg(2+) ion was observed.