Condensation and salt-induced decondensation of DNA upon incorporation of a V-shaped luminescent [Ru2(bpy)4(mbpibH2)]4+

This paper first reports on the condensation of DNA to a tightly packed state induced by a V-shaped di-ruthenium(II) complex [Ru-2(bpy)(4)(mbpibH(2))]Cl-4 (bpy = 2,2'-bipyridine and mbpibH(2) = 1,3-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene), which binds to the groove of herring sperm DNA (hsDNA) with the binding constant of 2.0 x 10(7) M-1 (0.05 M NaCl, pH 72). The di-Ru(II) complex is found to induce the condensation of both hsDNA to long chain-like particle clusters and originally circular plasmid pBR322 DNA to particulate structure under neutral conditions. More interestingly, the presence of NaCl has a significant impact on the condensation and decondensation of DNA upon incorporation of [Ru-2(bpy)(4)(mbpibH(2))](4+), representing tunable luminescence characteristics by NaCl. High salt concentration facilitates the decondensation of DNA-[Ru-2(bpy)(4)(mbpibH(2))](4+) adducts. The results from this study offer an effective method to control the condensation and decondensation of DNA upon incorporation of luminescent concentrators. (C) 2013 Elsevier Inc. All rights reserved.