-
[show abstract]
[hide abstract]
ABSTRACT: The emission enhancement behavior and photocleavage activity of a ruthenium(ii) arene complex, [(η6-p-cymene)Ru(dppn)(py)]2+ () (dppn = 4,5,9,16-tetraaza-dibenzo[a,c]naphthacene, py = pyridine), towards DNA were compared with [(η6-p-cymene)Ru(bpy)(py)]2+ (), [Ru(bpy)2(dppz)]2+ () and [Ru(bpy)2(dppn)]2+ () (bpy = 2,2'-bipyridine, dppz = dipyrido-[3,2-a:2',3'-c]phenazine). It was found that emits fluorescence from the dppn-based ligand-centered (LC) singlet excited state and generates singlet oxygen (1O2) from the dppn-based LC triplet excited state. As a result, displays emission enhancement behavior and photocleavage activity towards DNA simultaneously. In contrast, is the most classical DNA light switch but shows poor DNA photocleavage activity, while is an efficient DNA photocleaver but cannot report DNA binding by luminescence enhancement. An increased cytotoxicity against human lung carcinoma cells A549 by about 10-fold was also observed for upon visible light activation. These intriguing properties result from the unique combination of the Ru(ii) arene and dppn subunits.
Dalton Transactions 03/2013; · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Nanoscaled coordination polymers based on biologically prevalent ions have potential applications in drug delivery and biomedical imaging. Herein, coordination polymer nanoparticles of anionic porphyrins, including meso-tetra(4-carboxyphenyl)-porphyrin (H(2) TCPP(4-) ) and meso-tetra(4-sulfonatophenyl)-porphyrin (H(2) TPPS(4-) ), and alkaline or alkaline earth metal cations, such as K(+) and Ca(2+) , were constructed in aqueous solution in the presence of cucurbit[7]uril (CB7) or cucurbit[8]uril (CB8). UV/Vis absorption and fluorescence spectroscopy, dynamic light scattering (DLS), scanning electron spectroscopy (SEM), and atomic force microscopy (AFM) were applied to explore the assembly and particle formation of porphyrin anions and metal cations mediated by CBn. The particle size depends on the kinds of CBn and metal cations and their concentrations. The uptake of H(2) TPPS(4-) particles by tumor cells (A549 cells) was found to be more efficient than H(2) TPPS(4-) at 37 °C, showing the application potential of such assembled particles in biology and medicine.
ChemPhysChem 02/2013; · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Still fluorescent upon coordination to Ru: [(η(6) -p-cymene)Ru(dppn)(py)](2+) (dppn=4,5,9,16-tetraaza-dibenzo[a,c]naphthacene) is highly fluorescent due to the coordinated dppn with a fluorescence quantum yield of 0.31 in acetonitrile, which is nearly the same as free dppn (0.33) and one of the highest of all luminescent Ru(II) complexes. The underlying mechanism may shed light on the development of Ru(II) arene-based anticancer theranostic agents.
Chemistry 06/2012; 18(28):8617-21. · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Two new NIR-absorbing BODIPY dyes, each bearing two pyridinium groups, are synthesized and their DNA-binding affinities and DNA photocleavage abilities examined in depth. While one BODIPY dye photocleaves DNA mainly through singlet oxygen, the other photocleaves DNA through both singlet oxygen and hydroxyl radical. To the best of our knowledge, this is the first example of a hydroxyl radical being involved in the photodynamic behavior of BODIPY-type dyes. EPR experiments confirm the ability of these and several related BODIPYs to generate superoxide anion radical and hydroxyl radical. This finding may shed light on the mechanism of BODIPY-based photodynamic therapy (PDT) and open a new avenue for development of more efficient BODIPY-type PDT agents.
ChemPhysChem 05/2012; 13(11):2739-47. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Two dirhodium(II) complexes, [Rh(II)(2)(μ-O(2)CCH(3))(2)(bpy)(2)](O(2)CCH(3))(2) (Rh(2)bpy(2); bpy = 2,2'-bipyridine) and [Rh(II)(2)(μ-O(2)CCH(3))(2)(phen)(2)](O(2)CCH(3))(2) (Rh(2)phen(2); phen = 1,10-phenanthroline) were synthesized, and their photocatalytic H(2) production activities were studied in multicomponent systems, containing [Ir(III)(ppy)(2)(dtbbpy)](+) (ppy = 2-phenylpyridine, dtbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) as the photosensitizer (PS) and triethylamine as the sacrificial reductant (SR). There is a more than 6-fold increase in the photocatalytic activity from Rh(2)bpy(2) to Rh(2)phen(2) just using phen in place of bpy. A turnover number as high as 2622 was obtained after 50 h of irradiation of a system containing 16.7 μM Rh(2)phen(2), 50 μM PS, and 0.6 M SR. The electrochemical, luminescence quenching, and transient absorption experiments demonstrate that Rh(I)Rh(I) is the true catalyst for the proton reduction. The real-time absorption spectra confirm that a new Rh-based species formed upon irradiation of the Rh(2)phen(2)-based multicomponent system, which exhibits an absorption centered at ∼575 nm. This 575-nm intermediate may account for the much higher H(2) evolution efficiency of Rh(2)phen(2). Our work highlights the importance of N-based chelate ligands and opens a new avenue for pursuing more efficient Rh(II)(2)-based complexes in photocatalytic H(2) production application.
Inorganic Chemistry 05/2012; 51(11):6376-84. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: pH-responsive 1O2 photosensitizing systems may serve as selective photodynamic therapy (PDT) agents by targeting the acidic interstitial fluid
of many kinds of tumors. In this work, a natural and clinically used photosensitizer (Hypocrellin B, HB) and a pH indicator
(Bromocresol Purple, BCP) were co-encapsulated in organically modified silica nanoparticles. BCP successfully regulated the
1O2 generation efficiency of HB through the “inner filter” effect, which shows much stronger 1O2 generation ability in an acidic than in a basic environment. In vitro experiments also demonstrated that HB-doped nanoparticles are effective in killing tumor cells by PDT.
Keywordsphotodynamic therapy-pH responsive-bromocresol purple-hypocrellin b-silica nanoparticles
Science China-Chemistry 04/2012; 53(9):1994-1999. · 1.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To track nuclear dynamic processes by fluorescence imaging, nuclear stains should be highly fluorescent, resistant to photobleaching, and inert to nuclear processes. The nuclear stains of the Hoechst family, such as Hoechst 34580, show bright fluorescence only on groove binding to DNA, and therefore may interfere with visualization of nuclear dynamic processes induced by other stimuli. We study host-guest interactions between Hoechst 34580 and Cucurbit[7]uril (CB7) in aqueous solutions. The formation of CB7-Hoechst 34580 inclusion complexes with stoichiometry of 2:1 in water and 1:1 in phosphate-buffered saline (PBS) solution (pH 7.0) is confirmed by (1)H NMR, absorption spectra, fluorescence spectra, MALDI-TOF MS, and molecular modeling. Compared to Hoechst 34580, the inclusion complex exhibits redshifted absorption, intensified fluorescence, improved photostability, weakened DNA binding affinity, comparable ability to penetrate cell nuclei, and better nuclear-staining capability, and thus a new avenue for the application of cucurbituril in fluorescence imaging is opened.
ChemPhysChem 09/2011; 12(16):2933-40. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: [Ru(II)(bpy)(2)(dppn)](2+) (bpy = 2,2'-bipyridine, dppn = 4,5,9,16-tetraazadibenzo[a,c]naphthacene) was found to be able to photoinactivate Gram-negative Escherichia coli efficiently, showing the potential of transition-metal complexes as photosensitizers in the field of photodynamic antimicrobial chemotherapy (PACT).
Photochemical and Photobiological Sciences 03/2011; 10(6):887-90. · 2.58 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Binding affinity towards serum albumin and intracellular proteins is of importance for a photodynamic therapy (PDT) sensitizer to selectively localize in tumours and efficiently induce cell death. In this paper, it was found that cucurbit[8]uril (CB8) can greatly improve the binding affinity of 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP), a promising PDT photosensitizer, towards bovine serum albumin (BSA). Absorption, fluorescence emission, (1)H NMR, dynamic light scattering, atomic force microscope, as well as protein photocleavage measurements suggest that the binding enhancement originates from the formation of a ternary complex of CB8·TMPyP·tryptophan residues. This finding opens up a new approach for the development of more efficient PDT agents.
Physical Chemistry Chemical Physics 10/2010; 12(40):13255-60. · 3.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Four meso-tetraphenylporphyrin derivatives bearing either triphenylphosphonium ion-(P1 and P2) or triethylammonium ion-(P3 and P4) terminated alkoxy group at either para-(P1 and P3) or meta-(P2 and P4) position of one meso-phenyl group were designed and synthesized. P1-P4 show similar absorption and fluorescence emission spectra and (1)O(2) quantum yields. The more lipophilic nature of triphenylphosphonium ion over triethylammonium ion renders P1 and P2 higher octanol/water partition coefficients than P3 and P4. Confocal fluorescence microscopy proved that P1-P4 are all mitochondria-targeting. MTT assay showed that P1-P4 presented significant phototoxicity at the concentrations that dark toxicity is negligible towards human breast cancer cell line MCF-7 cells, displaying their application potential in PDT.
Journal of photochemistry and photobiology. B, Biology 02/2010; 98(2):167-71. · 1.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: pH-responsive (1)O(2) photosensitizing systems may serve as selective photodynamic therapy (PDT) agents by targeting the acidic interstitial fluid of many kinds of tumors. In this work, we present a pH-responsive nanoparticle-based platform for controllable (1)O(2) generation, in which a hydrophobic (1)O(2) photosensitizer (meso-tetraphenylporphyrin, TPP) and a pH indicator (Bromocresol Purple, BCP, or Bromothymol Blue, BTB) are simultaneously encapsulated in organically modified silica nanoparticles (OSNP). In basic conditions, the pH indicator absorbs light competitively and thus restricts sensitizer excitation. In acidic solution, the blue shifted absorption of the pH indicator allows the efficient excitation of the sensitizer. The pH indicator serves as an 'inner filter' to modulate effectively the excitation of the sensitizer and thus the (1)O(2) generation efficiency.
Nanotechnology 02/2010; 21(11):115102. · 3.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The photodynamic properties of a new hypocrellin B (HB) derivative bearing a bispyrrolecarboxamide pendant (HB-Net) were investigated in detail. EPR experiments revealed that the generation ability of reactive oxygen species (ROS) of HB-Net is inferior to that of HB. DNA melting temperature measurements and ethidium bromide (EB) displacement assay illustrated the affinity of HB-Net toward dsDNA as the result of the bispyrrolecarboxamide unit, which is structurally related to the well-known minor groove binder netropsin. The radical generation abilities of HB and HB-Net can be enhanced by ascorbic acid via the photoinduced electron transfer from ascorbic acid to the photosensitizer, however, only the DNA photodamage capability of HB-Net can be improved significantly by ascorbic acid due to the stronger affinity of HB-Net to DNA. Consequently, the combination of HB-Net and ascorbic acid may lead to efficient DNA photodamage even in anaerobic conditions.
The Journal of Physical Chemistry B 08/2008; 112(32):9959-65. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three long-wavelength absorbing dipeptide-modified hypocrellin B (HB) derivatives, Gly-HB, Tyr-HB, and Trp-HB, were prepared for application in photodynamic therapy (PDT). Their abilities to produce free radicals and singlet oxygen were compared in detail with EPR technique, and their binding interactions with calf thymus DNA (CT DNA) were studied by absorption spectra and DNA melting temperature measurements. Tyr-HB and Trp-HB distinguish themselves from Gly-HB and HB remarkably by their significantly improved efficiencies to generate semiquinone anion radicals, superoxide anion radicals, and hydroxyl radicals, as well as their affinity to CT DNA, as the result of the electron-donating properties and intercalating abilities of tyrosine and tryptophan groups. Tyr-HB and Trp-HB show remarkably enhanced photodamage capabilities on CT DNA than their parent HB in aerobic conditions. Moreover, they possess moderate photodamage abilities on CT DNA even in anaerobic conditions, indicating the role of Type I mechanism in their photodynamic behaviors.
The Journal of Physical Chemistry B 05/2007; 111(14):3742-9. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fifteen complexes of hypocrellin A (HA) with rare earth trivalent ions (except Pm3+) along with the complex of HA with Sc3+ were prepared, and their photodynamic activities, including absorption in the phototherapeutic window (600-900 nm); water-solubility; triplet lifetime; generation of reactive oxygen species (ROS), such as singlet oxygen (1O2), superoxide anion radical (O2-*), and hydroxyl radical (OH*); generation of semiquinone anion radical; and affinity to DNA, as well as photosensitized damage on calf thymus DNA (CT DNA), were compared in detail using the UV-visible spectrum, fluorescence spectrum, spin-trapping EPR technique, and laser photolysis technique. All complexes exhibit a red-shifted absorption spectrum, an increased absorbance above 600 nm, improved water solubility, and an enhanced affinity to CT DNA over the parent HA. For ions that possess low-energy excited states, including Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+, the corresponding complexes show undetectable or nearly undetectable fluorescence, a triplet excited-state lifetime, generation of ROS, and photodamage in CT DNA. In contrast, for ions that do not possess low-energy excited states, including Sc3+, Y3+, La3+, Gd3+, and Lu3+, the corresponding complexes exhibit higher photodamage abilities with CT DNA with respect to HA, benefitting from both their comparable or even higher 1O2 quantum yields and an electrostatic affinity that is higher for DNA than HA.
The Journal of Physical Chemistry B 04/2007; 111(10):2688-96. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hypocrellin A (HA), an efficient phototherapeutic agent, can chelate with lanthanum ion to form a 1:1 complex, which exhibits enhanced 1O2 generation quantum yield, a red-shifted absorption window, greatly improved water solubility, a much lengthened triplet excited state lifetime, and an increased affinity to DNA with respect to HA. These effects in turn lead to a more potent photodamage ability on calf thymus DNA for La3+-HA than HA in both aerobic and anaerobic conditions, indicating the potential application of La3+-HA in the field of photodynamic therapy (PDT).
The Journal of Physical Chemistry B 11/2005; 109(41):19529-35. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We first synthesized and characterized a monomer ruthenium complex of hypocrellin B (HB) by chelation with Ru(bpy)2Cl2 (in which bpy=2,2'-bipyridine). It possesses the photosensitizing properties and can be applied in photodynamic therapy (PDT). The chemiluminescence assays indicated that the photodamage ability of the complex is stronger than that of HB.
Bioorganic & Medicinal Chemistry Letters 07/2005; 15(12):3067-70. · 2.55 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Complex monolayers of barbituric acid and melamine were formed by spreading a chloroform solution of amphiphilic barbituric acid on the subphase of melamine solution. It was confirmed that the complex monolayer was formed through in situ complementary hydrogen bonding at the air-water interface. It was interesting to find that the complex LB films showed supramolecular chirality although both of the molecules were achiral, as verified by the circular dichroism spectral measurements. It was suggested that the pi-pi stacking of the neighboring barbituric acid and melamine group in a helical sense resulted in the chirality of the molecular assemblies. Due to the directionality of the hydrogen bonding, the BA-M film could form regular aligned nanofibers on the AFM images. Increasing the subphase temperature will lead to the decrease of CD intensity and the change of the morphologies. We suggested that the strength of the hydrogen bonding resulted in the difference.
Journal of Colloid and Interface Science 06/2005; 285(2):680-5. · 3.07 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An amphiphilic barbituric acid derivative was found to form stable monolayers showing a clear phase transition at the air/water interface. It is interesting to find that the deposited Langmuir-Blodgett (LB) films of the compound showed circular dichroism (CD) although the molecule itself was achiral. AFM measurements on the transferred one-layer LB film revealed that spiral nanoarchitectures were formed. It was further found that the supramolecular chirality of the LB films was related to symmetry breaking at the interface. Hydrogen bonding and the pi-pi stacking between the neighboring molecules resulted in chiral fibers which formed the spiral structures. To the best of our knowledge, this is the first report on the chirality of the molecular assemblies and spiral nanostructures formed through the air/water interface by achiral molecules.
Journal of the American Chemical Society 03/2004; 126(5):1322-3. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A water-insoluble porphyrin derivative was studied in Triton X-100 micelles by steady-state spectroscopy and picosecond photolysis. The porphyrin in micelles formed J aggregates, and, consequently, the excited-state lifetime of such a porphyrin was very short. After the addition of colloidal SiO2, the B-band absorption blue-shifted, forming a broad absorption peak. This peak can be ascribed to the monomer-dominated absorption of porphyrin. The photolysis experiment showed that the dynamic curve of the porphyrin with SiO2 exhibited a rapid recovery plus an offset resulting from the S1 state absorption. The long lifetime part constituted about half of the total absorption. Such a long-lifetime component could be ascribed to the absorption of monomeric porphyrin. The fluorescence near-field scanning optical microscopy showed that the porphyrin in the presence of SiO2 exhibited stronger fluorescence images compared with that in the absence of SiO2, though the topography images of the these samples were similar. The monomeric dispersion of porphyrin in SiO2 solution may be due to its inset in the fragmented bilayers on the surface of the SiO2 particles, assisted by the hydrogen bond between the amino group and the ionized silanol of SiO2. The prolonged excited lifetime can be greatly beneficial to the application of porphyrin in heterogeneous photosensitization or photocatalysis.
02/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: The electron spin resonance spectrum of superoxide anion radical adsorbed on the surface of colloidal TiO2 was detected directly at room temperature for the first time. This signal was generated partially by porphyrin-sensitized titanium dioxide, i.e., the reduction of adsorbed oxygen on the TiO2 nanocluster surface by the just injected electron from the excited porphyrin.
02/2004;
