Synthesis, Biomacromolecular Interactions, Photodynamic No Releasing And Cellular Imaging Of Two [Rucl(Qn)(Lbpy)(No)]X Complexes

Two light-activated NO donors [RuCl(qn)(Lbpy)(NO)]X with 8-hydroxyquinoline (qn) and 2,2'-bipyridine derivatives (Lbpy) as co-ligands were synthesized (Lbpy(1) = 4,4'-dicarboxyl-2,2'-dipyridine, X = Cl- and Lbpy(2) = 4,4'-dimethoxycarbonyl-2,2'-dipyridine, X = NO3-), and characterized using ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (H-1 NMR), elemental analysis and electrospray ionization mass spectrometry (ESI-MS) spectra. The [RuCl(qn)(Lbpy(2))(NO)]NO3 complex was crystallized and exhibited distorted octahedral geometry, in which the Ru-N(O) bond length was 1.752(6) angstrom and the Ru-N-O angle was 177.6(6)degrees. Time-resolved FT-IR and electron paramagnetic resonance (EPR) spectra were used to confirm the photoactivated NO release of the complexes. The binding constant (K-b) of two complexes with human serum albumin (HSA) and DNA were quantitatively evaluated using fluorescence spectroscopy, Ru-Lbpy(1) (K-b similar to 10(6) with HSA and similar to 10(4) with DNA) had higher affinity than Ru-Lbpy(2). The interactions between the complexes and HSA were investigated using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) and EPR spectra. HSA can be used as a carrier to facilitate the release of NO from the complexes upon photoirradiation. The confocal imaging of photo-induced NO release in living cells was successfully observed with a fluorescent NO probe. Moreover, the photocleavage of pBR322 DNA for the complexes and the effect of different Lbpy substituted groups in the complexes on their reactivity were analyzed.