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Biophysical Journal Feb 1999We have implemented simultaneous picosecond pulsed two- and three-photon excitation of near-UV and visible absorbing fluorophores in a scanning near-field optical...
We have implemented simultaneous picosecond pulsed two- and three-photon excitation of near-UV and visible absorbing fluorophores in a scanning near-field optical microscope (SNOM). The 1064-nm emission from a pulsed Nd:YVO4 laser was used to excite the visible mitochondrial specific dye MitoTracker Orange CM-H2TMRos or a Cy3-labeled antibody by two-photon excitation, and the UV absorbing DNA dyes DAPI and the bisbenzimidazole BBI-342 by three-photon excitation, in a shared aperture SNOM using uncoated fiber tips. Both organelles in human breast adenocarcinoma cells (MCF 7) and specific protein bands on polytene chromosomes of Drosophila melanogaster doubly labeled with a UV and visible dye were readily imaged without photodamage to the specimens. The fluorescence intensities showed the expected nonlinear dependence on the excitation power over the range of 5-40 mW. An analysis of the dependence of fluorescence intensity on the tip-sample displacement normal to the sample surface revealed a higher-order function for the two-photon excitation compared to the one-photon mode. In addition, the sample photobleaching patterns corresponding to one- and two-photon modes revealed a greater lateral confinement of the excitation in the two-photon case. Thus, as in optical microscopy, two-photon excitation in SNOM is confined to a smaller volume.
Topics: Animals; Antibodies; Chromosomes; Drosophila melanogaster; Fluorescent Dyes; Humans; Lasers; Microscopy, Fluorescence; Mitochondria; Photons; Tumor Cells, Cultured; Ultraviolet Rays
PubMed: 9916041
DOI: 10.1016/S0006-3495(99)77274-7 -
Royal Society Open Science Sep 2022In this study, a series of 14 Cu (II), Zn (II), Ni (II) and Ag (I) complexes containing bis-benzimidazole derivatives were successfully designed and synthesized from...
In this study, a series of 14 Cu (II), Zn (II), Ni (II) and Ag (I) complexes containing bis-benzimidazole derivatives were successfully designed and synthesized from 2-(1-benzimidazole-2-yl)-phenol derivatives and corresponding metal salt solutions. The compound structures were identified by FT-IR, H-NMR, powder X-ray diffraction and ESI-MS analyses, and the presence of the metal in the complexes was confirmed by ultraviolet-visible spectroscopy and ICP optical emission spectrometry. Electronic structure calculations were also carried out to describe the detailed structures in addition to the electronic absorption spectra of the ligands. The cytotoxic activity of the complexes was evaluated against three human cancer cell lines: lung (A549), breast (MDA-MB-231) and prostate (PC3) cancer cells. All complexes inhibited anti-proliferative cancer cells better than free ligands, especially Zn (II) and Ag (I) complexes, which are most sensitive to MDA-MB-231 cells. In addition, showing the growth inhibition of three cancer cell lines with IC < 10.4 µM, complexes , and could be considered potential multi-targeted anti-cancer agents.
PubMed: 36147940
DOI: 10.1098/rsos.220659 -
Chemical Science Oct 2015miRNAs are important components of regulatory networks that control gene expression and have implications in various diseases including cancer. Targeting oncogenic...
miRNAs are important components of regulatory networks that control gene expression and have implications in various diseases including cancer. Targeting oncogenic miRNAs with small molecules is currently being explored to develop cancer therapeutics. Here, we report the development of dual binding neomycin-bisbenzimidazole conjugates that target oncogenic miR-27a with high affinity ( = 1.2 to 7.4 × 10 M). These conjugates bring significant reduction (∼65% at 5 μM) in mature miRNA levels and penetrate easily in the cells where they localise both in the cytoplasm and the nucleus. Cell cycle analysis showed significant increase in the G0/G1 phase (∼15%) and decrease in the S phase (∼7%) upon treatment with neomycin-bisbenzimidazole conjugates, suggesting inhibition of cell proliferation. Using the conjugation approach, we show that moderately binding ligands can be covalently combined into high affinity binders. This study also highlights the role of linker optimization in designing high affinity ligands for miR-27a targeting.
PubMed: 29861909
DOI: 10.1039/c5sc01969a -
Cytometry. Part a : the Journal of the... May 2013
Topics: Bisbenzimidazole; Fluorescent Dyes; Humans; Indoles; Light; Microscopy, Fluorescence; Protons; Ultraviolet Rays
PubMed: 23610064
DOI: 10.1002/cyto.a.22279 -
Frontiers of Optoelectronics Apr 2023Single perylene diimide (PDI) used as a non-fullerene acceptor (NFA) in organic solar cells (OSCs) is enticing because of its low cost and excellent stability. To...
Single perylene diimide (PDI) used as a non-fullerene acceptor (NFA) in organic solar cells (OSCs) is enticing because of its low cost and excellent stability. To improve the photovoltaic performance, it is vital to narrow the bandgap and regulate the stacking behavior. To address this challenge, we synthesize soluble perylenetetracarboxylic bisbenzimidazole (PTCBI) molecules with a bulky side chain at the bay region, by replacing the widely used "swallow tail" type alkyl chains at the imide position of PDI molecules with a planar benzimidazole structure. Compared with PDI molecules, PTCBI molecules exhibit red-shifted UV-vis absorption spectra with larger extinction coefficient, and one magnitude higher electron mobility. Finally, OSCs based on one soluble PTCBI-type NFA, namely MAS-7, exhibit a champion power conversion efficiency (PCE) of 4.34%, which is significantly higher than that of the corresponding PDI-based OSCs and is the highest PCE of PTCBI-based OSCs reported. These results highlight the potential of soluble PTCBI derivatives as NFAs in OSCs.
PubMed: 37087536
DOI: 10.1007/s12200-023-00063-6 -
Chromosoma Jun 2018The fluorescent dye 4'-6-Diamidino-2-phenylindole (DAPI) is frequently used in fluorescence microscopy as a chromosome and nuclear stain because of its high specificity...
The fluorescent dye 4'-6-Diamidino-2-phenylindole (DAPI) is frequently used in fluorescence microscopy as a chromosome and nuclear stain because of its high specificity for DNA. Normally, DAPI bound to DNA is maximally excited by ultraviolet (UV) light at 358 nm, and emits maximally in the blue range, at 461 nm. Hoechst dyes 33258 and 33342 have similar excitation and emission spectra and are also used to stain nuclei and chromosomes. It has been reported that exposure to UV can convert DAPI and Hoechst dyes to forms that are excited by blue light and emit green fluorescence, potentially confusing the interpretation of experiments that use more than one fluorochrome. The work reported here shows that these dyes can also be converted to forms that are excited by green light and emit red fluorescence. This was observed both in whole tissues and in mitotic chromosome spreads, and could be seen with less than 10-s exposure to UV. In most cases, the red form of fluorescence was more intense than the green form. Therefore, appropriate care should be exercised when examining tissues, capturing images, or interpreting images in experiments that use these dyes in combination with other fluorochromes.
Topics: Animals; Artifacts; Benzimidazoles; Bisbenzimidazole; Brain; Chromosomes, Insect; DNA; Drosophila melanogaster; Fluorescent Dyes; Indoles; Larva; Male; Metaphase; Microscopy, Fluorescence; Photobleaching; Testis; Ultraviolet Rays
PubMed: 29234867
DOI: 10.1007/s00412-017-0654-5 -
Cytometry. Part a : the Journal of the... Sep 2005Live cell fluorescence microscopy experiments often require visualization of the nucleus and the chromatin to determine the nuclear morphology or the localization of...
BACKGROUND
Live cell fluorescence microscopy experiments often require visualization of the nucleus and the chromatin to determine the nuclear morphology or the localization of nuclear compartments.
METHODS
We compared five different DNA dyes, TOPRO-3, TOTO-3, propidium iodide, Hoechst 33258, and DRAQ5, to test their usefulness in live cell experiments with continuous imaging and photobleaching in widefield epifluorescence and confocal laser scanning microscopy. In addition, we compared the DNA stainings with fluorescent histones as an independent fluorescent label to mark chromatin.
RESULTS
From the dyes tested, only Hoechst and DRAQ5 could be used to stain DNA in living cells. However, DRAQ5 had several advantages, namely low photobleaching, labeling of the chromatin compartments comparable to that of H2B-GFP fusion proteins, and deep red excitation/emission compatible with available genetically encoded fluorescent proteins such as C/G/YFP or mRFP.
CONCLUSIONS
The DNA dye DRAQ5 is well suited for chromatin visualization in living cells and can easily be combined with other fluorophores with blue to orange emission.
Topics: Animals; Anthraquinones; Bisbenzimidazole; Cell Line; Coloring Agents; DNA; Fluorescence Recovery After Photobleaching; Fluorescent Dyes; Humans; Intercalating Agents; Nitrogen Oxides; Propidium; Quinolines; Staining and Labeling; Thiazoles
PubMed: 16082711
DOI: 10.1002/cyto.a.20172 -
The Journal of Biological Chemistry Jan 1999Glucocorticoid receptor (GR) recycles between an inactive form complexed with heat shock proteins (hsps) and localized to the cytoplasm and a free liganded form that...
Glucocorticoid receptor (GR) recycles between an inactive form complexed with heat shock proteins (hsps) and localized to the cytoplasm and a free liganded form that regulates specific gene transcription in the nucleus. We report here that, contrary to previous assumptions, association of GR into hsp-containing complexes is not sufficient to prevent the shuttling or trafficking of the GR across the nuclear membrane. Following the withdrawal of treatment with cortisol or the hormone antagonist RU486, GRs recycled rapidly into hsp-associated, hormone-responsive complexes. However, cortisol-withdrawn receptors redistributed to the cytoplasm very slowly (t(1)/(2) = 8-9 h) and RU486-withdrawn receptors not at all. Persistent localization of these GRs to the nucleus was not due to a gross defect in export, since in both instances the complexed nuclear GRs transferred efficiently between heterokaryon nuclei. Moreover, the addition of a nuclear retention signal to the N terminus of GR induced the transfer of naive receptor to the nucleus in the absence of steroid. These results suggest that the localization of GR to the cytoplasm is determined by fine control of the rates of transfer of GR across the nuclear membrane and/or by active retention that occurs independently from the association of GR with hsps.
Topics: 3T3 Cells; Animals; Biological Transport; Bisbenzimidazole; COS Cells; Cell Nucleus; Cytoplasm; Fluorescent Dyes; Heat-Shock Proteins; Hormone Antagonists; Hydrocortisone; Ligands; Mice; Mifepristone; Protein Conformation; Rats; Receptors, Glucocorticoid; Structure-Activity Relationship; Transcription, Genetic; Tumor Cells, Cultured
PubMed: 9880517
DOI: 10.1074/jbc.274.3.1432 -
Communications Biology Feb 2023Type IA topoisomerases maintain DNA topology by cleaving ssDNA and relaxing negative supercoils. The inhibition of its activity in bacteria prevents the relaxation of...
Type IA topoisomerases maintain DNA topology by cleaving ssDNA and relaxing negative supercoils. The inhibition of its activity in bacteria prevents the relaxation of negative supercoils, which in turn impedes DNA metabolic processes leading to cell death. Using this hypothesis, two bisbenzimidazoles, PPEF and BPVF are synthesized, selectively inhibiting bacterial TopoIA and TopoIII. PPEF stabilizes the topoisomerase and topoisomerase-ssDNA complex, acts as an interfacial inhibitor. PPEF display high efficacy against ~455 multi-drug resistant gram positive and negative bacteria. To understand molecular mechanism of inhibition of TopoIA and PPEF, accelerated MD simulation is carried out, and results suggested that PPEF binds, stabilizes the closed conformation of TopoIA with -6Kcal/mol binding energy and destabilizes the binding of ssDNA. The TopoIA gate dynamics model can be used as a tool to screen TopoIA inhibitors as therapeutic candidates. PPEF and BPVF cause cellular filamentation and DNA fragmentation leading to bacterial cell death. PPEF and BPVF show potent efficacy against systemic and neutropenic mouse models harboring E. coli, VRSA, and MRSA infection without cellular toxicity.
Topics: Animals; Mice; Escherichia coli; DNA Topoisomerases, Type I; Bisbenzimidazole; DNA; DNA, Single-Stranded
PubMed: 36807602
DOI: 10.1038/s42003-023-04412-1 -
ACS Omega Nov 2023Rhenium(I)tricarbonyl core-based heteroleptic "figure-eight"- and Z-shaped metallocycles (-) of the general formula -[{(CO)Re(μ-L)Re(CO)}(dppz)] were self-assembled...
Rhenium-Pyrazolyl-Based Figure-Eight- and Z-Shaped Metallocycles: Self-Assembly, Solid-State Structures, Dynamic Properties in Solution, and Competitive Ligand-Induced Supramolecular Transformations into Rhenium-Pyridyl/-Benzimidazolyl/-Phosphine-Based Metallocycles/Acyclic Complexes.
Rhenium(I)tricarbonyl core-based heteroleptic "figure-eight"- and Z-shaped metallocycles (-) of the general formula -[{(CO)Re(μ-L)Re(CO)}(dppz)] were self-assembled from Re(CO), H-L (H-L = 5,8-dihydroxy-1,4-naphthaquinone (H-dhnq) for ; 1,4-dihydroxy-9,10-anthraquinone (H-dhaq) for ; 6,11-dihydroxy-5,12-naphthacenedione (H-dhnd) for ; 2,2'-bisbenzimidazole (H-bbim) for ), and bis(4-((pyrazolyl)methyl)phenylmethane) (dppz) via one-pot coordination-driven synthetic approach. The molecular structures of and were unambiguously confirmed by single-crystal X-ray diffraction (SC-XRD) methods. The metallocycles in the DMSO solution exist as an acyclic dinuclear-DMSO adduct of the general formula -[{(CO)Re(μ-L)Re(CO)}(DMSO)] (, L = dhnq; , L = dhaq; , L = dhnd; , L = bbim) and dppz, which are in dynamic equilibrium. The dynamic behavior of the rhenium-pyrazolyl bond in the solution state was effectively utilized to transform metallocycles - into pyridyl/benzimidazolyl/phosphine donor-based heteroleptic metallocycles and acyclic dinuclear complexes (-). These include tetranuclear rectangles -[{(CO)Re(μ-L)Re(CO)}(4,4'-bpy)] ( and , L = dhaq for and bbim for ), dinuclear metallocycles -[{(CO)Re(μ-L)Re(CO)}(dpbim)] (- and ; L = dhnq for , dhaq for , dhnd for , and bbim for ), and dinuclear acyclic complexes -[{(CO)Re(μ-L)Re(CO)}(PTA)] (- and ; L = dhnq for , dhaq for , dhnd for , and bbim for ). These transformations were achieved through component-induced supramolecular reactions while treating with competitive ligands 4,4'-bipyridine (4,4'-bpy), bis(4-((1-benzoimidazole-1-yl)methyl)phenyl)methane (dpbim), and 1,3,5-triaza-7-phosphaadamantane (PTA). The reaction mixture in the solution was analyzed using NMR and electrospray ionization mass spectrometry (ESI-MS) analysis. Additionally, crystal structures of , , and , which were obtained in the mixture of the solutions, were determined, providing unequivocal evidence for the occurrence of supramolecular transformation within the system. The results reveal that the size of the chelating ligand and the pyrazolyl donor angle of the ditopic ligand play crucial roles in determining the resulting solid-state metallacyclic architecture in these synthetic combinations. The dynamic behavior of the rhenium-pyrazolyl bond in the metallocycles can be utilized to transform into other metallocycles and acyclic complexes using suitable competing ligands via ligand-induced supramolecular transformations.
PubMed: 37969972
DOI: 10.1021/acsomega.3c06371