The bimolecular sensitization of nitric oxide release from weak interacting ruthenium units

This work reports on the bimolecular sensitization of nitric oxide release from cis-[Ru(bpy)(2)(iso)-NO](PF(6))(3) (1) (iso = isoquinoline and bpy = 2,2`- bipyridine) by irradiating the MLCT transition of the chloro analog cis-[Ru(bpy) 2(iso) Cl] PF6 (2). The compounds displayed peaks in the ESI-MS spectra at m/z 749.1 and m/z 578.1 ascribed, respectively, to ([1(NO(o))-2PF(6)center dot CH(3)OH](2+)) and ([2-PF(6)](+)). In the cyclic voltammograms, the nitrosyl complex presented two redox waves related to the NO ligand at 0.48 and -0.37 V (versus Ag/AgCl, NO(+/0/-1) processes), while the sensitizer showed two reversible waves at 0.79 and -1.46 V (versus Ag/AgCl, Ru(2+/3+) and bpy(0/-1), respectively). The most important feature of this system is that the nitrosyl compound does not have significant absorption in the visible region, while the sensitizer has an intense band centered at 496 nm. The irradiation of an equimolar mixture of the two compounds in an ethanol: water solution (v: v) with light of lambda > 500 nm leads to NO release, as probed by amperometric measurements. The variational method was applied, showing that the two compounds self-assembly in solution with a 1: 1 stoichiometry. Fluorescence spectra acquired at 77 K provided the E(0-0) for the system and, from the thermodynamic cycle it was estimated that the photoinduced electron transfer between the species has a Delta G value of -1.59 eV. (C) 2011 Elsevier B. V. All rights reserved.

Photocytotoxic activity of a nitrosyl phthalocyanine ruthenium complex - A system capable of producing nitric oxide and singlet oxygen

The synthesis, structural aspects, pharmacological assays, and in vitro photoinduced cytotoxic properties of [Ru(NO)(ONO)(pc)] (pc = phthalocyanine) are described. Its biological effect on the B16F10 cell line was studied in the presence and absence of visible light irradiation. At comparable irradiation levels, [Ru(NO) (ONO)(pc)] was more effective than [Ru(pc)] at inhibiting cell growth, suggesting that occurrence of nitric oxide release following singlet oxygen production upon light irradiation may be an important mechanism by which the nitrosyl ruthenium complex exhibits enhanced biological activity in cells. Following visible light activation, the [Ru(NO)(ONO)(pc)] complex displayed increased potency in B16F10 cells upon modifications to the photoinduced dose; indeed, enhanced potency was detected when the nitrosyl ruthenium complex was encapsulated in a drug delivery system. The liposome containing the [Ru(NO)(ONO)(pc)] complex was over 25% more active than the corresponding ruthenium complex in phosphate buffer solution. The activity of the complex was directly proportional to the ruthenium amount present inside the cell, as determined by inductively coupled plasma mass spectroscopy. Flow cytometry analysis revealed that the photocytotoxic activity was mainly due to apoptosis. Furthermore, the vasorelaxation induced by [Ru(NO)(ONO)(pc)], proposed as NO carrier, was studied in rat isolated aorta. The observed vasodilation was concentration-dependent. Taken together, the present findings demonstrate that the [Ru(NO)(ONO)(pc)] complex induces vascular relaxation and could be a potent anti-tumor agent. Nitric oxide release following singlet oxygen production upon visible light irradiation on a nitrosyl ruthenium complex produces two radicals and may elicit phototoxic responses that may find useful applications in photodynamic therapy. Crown Copyright (C) 2011 Published by Elsevier Inc. All rights reserved.

Photoinduced Nitric Oxide and Singlet Oxygen Release from ZnPC Liposome Vehicle Associated with the Nitrosyl Ruthenium Complex: Synergistic Effects in Photodynamic Therapy Application

Under continuous photolysis at 675 nm, liposomal zinc phthalocyanine associated with nitrosyl ruthenium complex [Ru(NH.NHq)(tpy)NO](3+) showed the detection and quantification of nitric oxide (NO) and singlet oxygen ((1)O(2)) release. Photophysical and photochemical results demonstrated that the interaction between the nitrosyl ruthenium complex and the photosensitizer can enable an electron transfer process from the photosensitizer to the nitrosyl ruthenium complex which leads to NO release. Synergistic action of both photosensitizers and the nitrosyl ruthenium complex results in the production of reactive oxygen species and reactive nitrogen species, which is a potent oxidizing agent to many biological tissues, in particular neoplastic cells.

HPLC separation, NMR and QTOF/MS/MS structure elucidation of a prominent nitric oxide donor agent based on an isomeric composition of a nitrosyl ruthenium complex

A new and promising nitrosyl ruthenium complex, [Ru(NO)(bdqi-COOH)(terpy)](PF(6))(3), bdqi-COOH is 3,4-diiminebenzoic acid and terpy is 2,2`-terpyridine, has been synthesized as a NO donor agent. The procedure used for [Ru(NO)(bdqi-COOH)(terpy)](PF(6))(3) synthesis has, apparently, yielded the formation of two isomers in which the ligand bdqi-COOH appears to be coordinated in its reduced form (bdcat-COOH), which could have differences in their pharmacological properties. Therefore, it was intended to separate the two possible isomers by high-performance liquid chromatography (HPLC) and to characterize them by high resolution mass spectrometry (QTOF MS) and by magnetic nuclear resonance spectroscopy (NMR). The results obtained by MS showed that the ESI-MS mass spectra of both HPLC column fractions, e.g. peak 1 and peak 2, are essentially equal, showing that both isomers display nearly identical gas-phase behavior with clusters of isotopologue ions centered at m/z 573, m/z 543 and m/z 513. Regarding the NMR analysis, the results showed that the positional isomerism is located in the bdqi-COOH ligand. From the observed results it can be concluded that the synthesis procedure that has been used results in the formation of two [Ru(terpy)(bdqi-COOH)NO](PF(6))(3) isomers. (c) 2009 Elsevier B.V. All rights reserved.

Photophysical and Complexation Studies of Chloro-Aluminum Phthalocyanine with Beta-Cyclodextrin and Hydroxypropyl-Beta-Cyclodextrin

A variety of nanostructures are being investigated as functional drug carriers for treatment of a wide range of diseases, most notably cardiovascular defects, autoimmune diseases, and cancer. The aim of this present contribution is to evaluate potentially applicable nanomaterials in the diagnosis and treatment of cancer due to their photophysical and photobiological properties and complexation behavior. The delivery systems consisted of chloro-aluminum phthalocyanine associated with beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin. The preparation of the complex and its stoichiometry in an ethanol/buffer (3:1) solution were studied by spectroscopic techniques, which were defined as 1:2. The inclusion complex in the nanometer scale was observed on the basis of changes to the spectroscopic properties. The singlet oxygen production and complex photophysical parameters were determined by measuring luminescence at 1270 nm and by steady state and time resolved spectroscopic, respectively. The preparation of the complex was tested and analyzed with regard to cellular damage by visible light activation. The inclusion complex showed a higher singlet oxygen quantum yield compared with other systems and other photoactive dyes. There was also a reduction in the fluorescence quantum yield compared with the results obtained for zinc phthalocyanine in organic medium. The results reported clearly that the inclusion complex chloro-aluminum phthalocyanine/cyclodextrin showed some changes in its spectroscopy properties leading to better biodistribution and biocompatibility with a potential application in photodynamic therapy, especially in the case of neoplasy. Additionally, it also has non-oncological applications as a drug delivery system.

Mitochondria, endoplasmic reticulum and actin filament behavior after PDT with chloroaluminum phthalocyanine liposomal in HeLa cells

Photodynamic therapy (PDT) for cancer is a therapeutic modality in the treatment of tumors in which visible light is used to activate a photosensitizer. Cell membranes have been identified as an important intracellular target for singlet oxygen produced during the photochemical pathway. This study analyzed the cytotoxicity in specific cellular targets of a photosensitizer used in PDT in vitro. The photosensitizing effects of chloroaluminum phthalocyanine liposomal were studied on the mitochondria, cytoskeleton and endoplasmic reticulum of HeLa cells. Cells were irradiated with a diode laser working at 670 nm, energy density of 4.5 J/cm(2) and power density of 45 mW/cm(2). Fluorescence microscopic analysis of the mitochondria showed changes in membrane potential. After PDT treatment, the cytoskeleton and endoplasmic reticulum presented basic alterations in distribution. The combined effect of AlPHCl liposomal and red light in the HeLa cell line induced photodamage to the mitochondria, endoplasmic reticulum and actin filaments in the cytoskeleton. (c) 2008 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.

Acidity and photolability of ruthenium salen nitrosyl and aquo complexes in aqueous solutions

The photochemical behavior of nitrosyl complexes Ru(salen)(NO)(OH(2))(+) and Ru(salen)(NO) Cl (salen = N, N`-ethylenebis-(salicylideneiminato) dianion) in aqueous solution is described. Irradiation with light in the 350-450 nm range resulted in nitric oxide (NO) release from both. For Ru(salen)(NO) Cl secondary photoreactions also resulted in chloride aquation. Thus, in both cases the final photoproduct is the diaquo cation Ru(III) (salen) (OH(2))(2)(+), for which pK(a)`s of 5.9 and 9.1 were determined for the coordinated waters. The pK(a) of the Ru(salen)(NO)(OH(2))+ cation was also determined as 4.5 +/- 0.1, and the relative acidities of these ruthenium aquo units are discussed in the context of the bonding interactions between Ru(III) and NO. (C) 2007 Elsevier B.V. All rights reserved.

Retrograde delivery of photosensitizer (TPPp-O-beta-GluOH)(3) selectively potentiates its photodynamic activity

Photodynamic therapy involves administration of a photosensitizing drug and its subsequent activation by visible light of the appropriate wavelength. Several approaches to increasing the specificity of photosensitizers for cancerous tissues and, in particular, through their conjugation to ligands that are directed against tumor-associated antigens have been investigated. Here, we have studied the delivery of the photocytotoxic porphyrin compound TPP(p-O-beta-D-GluOH)(3) into tumor cells that overexpress the glycosphingolipid Gb3, using the Gb3-binding nontoxic B-subunit of Shiga toxin (STxB) as a vector. To allow for site-directed chemical coupling, an STxB variant carrying a free sulfhydryl moiety at its C-terminal end has been used. Binding affinity, cellular uptake, singlet oxygen quantum yield, and phototoxicity of the conjugate have been examined. Despite some effect of coupling on both the photophysical properties of TPP(p-O-beta-D-GluOH)(3) and the affinity of STxB for its receptor, the conjugate exhibited a higher photocytotoxic activity than the photosensitizer alone and was exquisitely selective for Gb3-expressing tumor cells. Furthermore, our data strongly suggest that STxB-mediated retrograde delivery of the photosensitizer to the biosynthetic/secretory pathway is critical for optimal cytotoxic activity. In conclusion, a strong rationale for using retrograde delivery tools such as STxB in combination with photosensitizing agents for the photodynamic therapy of tumors is presented.

Spectroelectrochemical Properties and Lithium Ion Storage in Self-Assembled Nanocomposites from TiO(2)

Layer-by-layer (LbL) nanocomposite films from TiO(2) nanoparticles and tungsten-based oxides (WO(x)H(y)), as well as dip-coating films of TiO(2) nano particles, were prepared and investigated by electrochemical techniques under visible light beams, aiming to evaluate the lithium ion storage and chromogenic properties. Atomic force microscopy (AFM) images were obtained for morphological characterization of the Surface of the materials, which have similar roughness. Cyclic voltammetry and chronoamperometry measurements indicated high storage capacity of lithium ions in the LbL nanocomposite compared with the dip-coating film, which was attributed to the faster lithium ion diffusion rate within the self-assembled matrix. On the basis of the data obtained from galvanostatic intermittent titration technique (GITT), the values of lithium ion diffusion coefficient (D(Li)) for TiO(2)/WO(x)H(y) were larger compared with those for TiO(2). The rate of the coloration front in the matrices was investigated using a spectroelectrochemical method based oil GITT, allowing the determination of the ""optical"" diffusion coefficient (D(op)) as a function of the amount of lithium ions previously inserted into the matrices. The Values of D(Li) and D(op) suggested the existence of phases with distinct contribution to lithium ion diffusion rates and electrochromic efficiency. Moreover, these results aided a better understanding of the temporal change of current density and absorbance during the ionic electro-insertion, which is important for the possible application of these materials in lithium ion batteries and electrohromic devices.

Influence of irradiant energy on degree of conversion, polymerization rate and shrinkage stress in an experimental resin composite system

Objective. This study evaluated the degree of conversion (DC), maximum rate of cure (R(p)(max)), and polymerization stress (PS) developed by an experimental dental composite subjected to different irradiant energies (3,6,12, 24, or 48J/cm(2)) under constant irradiance (500 mw/cm(2)). Methods. DC and R(p)(max) were monitored for 10 min on the bottom surface of 2-mm thick disks and on 150-mu m thick films (representing the top of the specimen) using ATR-FTIR. PS was monitored for 10 min in 2-mm thick disks bonded to two glass rods (O = 5 mm) attached to a universal testing machine. One-way ANOVA/Tukey tests were used and differences in DC and R(p)(max) between top and bottom surfaces were examined using Student`s t-test. Statistical testing was performed at a pre-set alpha of 0.05. Results. For a given surface, DC showed differences among all groups, except at the top between 24 and 48 J/cm(2). R(p)(max) was similar among all groups at the same surface and statistically higher at the top surface. PS also showed significant differences among all groups. Data for 48 J/cm(2) were not obtained due to specimen failure at the glass/composite interface. Significance. Increases in irradiant exposure led to significant increases in DC and PS, but had no effect on R(p)(max) (c) 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Degree of conversion and mechanical properties of a BisGMA : TEGDMA composite as a function of the applied radiant exposure

Objective: Verify the influence of radiant exposure (H) on composite degree of conversion (DC) and mechanical properties. Methods: Composite was photoactivated with 3, 6, 12, 24, or 48 J/cm(2). Properties were measured after 48-h dry storage at room temperature. DC was determined on the flat surfaces of 6 mm x 2 mm disk-shaped specimens using FTIR. Flexural strength (FS) and modulus (FM) were accessed by three-point bending. Knoop microhardness number (KHN) was measured on fragments of FS specimens. Data were analyzed by one-way ANOVA/Tukey test, Student`s t-test, and regression analysis. Results: DC/top between 6 and 12 J/cm(2) and between 24 and 48 J/cm(2) were not statistically different. No differences between DC/top and bottom were detected. DC/bottom, FM, and KHN/top showed significant differences among all H levels. FS did not vary between 12 and 24 J/cm(2) and between 24 and 48 J/cm(2). KHN/bottom at 3 and 6 J/cm(2) was similar. KHN between top and bottom was different up to 12 J/cm(2). Regression analyses having H as independent variable showed a plateau region above 24 J/cm(2). KHN increased exponentially (top) or linearly (bottom) with DC. FS and FM increased almost linearly with DC/bottom up to 55% conversion. Conclusions: DC and mechanical properties increased with radiant exposure. Variables leveled off at high H levels. (C) 2007 Wiley Periodicals, Inc.

AFM analysis of bleaching effects on dental enamel microtopography

The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 mu m x 15 mu m area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum(380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment. (C) 2009 Elsevier B. V. All rights reserved.

Effect of power densities and irradiation times on the degree of conversion and temperature increase of a microhybrid dental composite resin

The different parameters used for the photoactivation process provide changes in the degree of conversion (DC%) and temperature rise (TR) of the composite resins. Thus, the purpose of this study was to evaluate the DC (%) and TR of the microhybrid composite resin photoactivated by a new generation LED. For the KBr pellet technique, the composite resin was placed into a metallic mould (1-mm thickness and 4-mm diameter) and photoactivated as follows: continuous LED LCU with different power density values (50-1000 mW/cm(2)). The measurements for the DC (%) were made in a FTIR Spectrometer Bomen (model MB-102, Quebec-Canada). The spectroscopy (FTIR) spectra for both uncured and cured samples were analyzed using an accessory for the diffuse reflectance. The measurements were recorded in the absorbance operating under the following conditions: 32 scans, 4-cm(-1) resolution, and a 300 to 4000-cm(-1) wavelength. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of the absorbance intensities of aliphatic C=C (peak at 1638 cm(-1)) against an internal standard before and after the curing of the specimen: aromatic C-C (peak at 1608 cm-1). For the TR, the samples were made in a metallic mould (2-mm thickness and 4-mm diameter) and photoactivated during 5, 10, and 20 s. The thermocouple was attached to the multimeter to allow the temperature readings. The DC (%) and TR were calculated by the standard technique and submitted to ANOVA and Tukey`s test (p < 0.05). The degree of conversion values varied from 35.0 (+/- 1.3) to 45.0 (+/- 2.4) for 5 s, 45.0 (+/- 1.3) to 55.0 (+/- 2.4) for 10 s, and 47.0 (+/- 1.3) to 52.0 (+/- 2.4) for 20 s. For the TR, the values ranged from 0.3 (+/- 0.01) to 5.4 (+/- 0.11)degrees C for 5 s, from 0.5 (+/- 0.02) to 9.3 (+/- 0.28)degrees C for 10 s, and from 1.0 (+/- 0.06) to 15.0 (+/- 0.95)degrees C for 20 s. The power densities and irradiation times showed a significant effect on the degree of conversion and temperature rise.

Generation and suppression of singlet oxygen in hair by photosensitization of melanin

We have studied the spectroscopic properties of hair (white, blond, red, brown, and black) under illumination with visible light, giving special emphasis to the photoinduced generation of singlet oxygen ((1)O(2)). Irradiation of hair shafts (lambda(ex)>400 nm) changed their properties by degrading the melanin. Formation of C3 hydroperoxides in the melanin indol groups was proven by (1)H NMR. After 532-nm excitation, all hair shafts presented the characteristic (1)O(2) emission (lambda(em) = 1270 nm), whose intensity varied inversely with the melanin content. (1)O(2) lifetime was also shown to vary with hair type, being five times shorter in black hair than in blond hair, indicating the role of melanin as a (1)O(2) suppressor. Lifetime ranged from tenths of a nanosecond to a few microseconds, which is much shorter than the lifetime expected for (1)O(2) in the solvents in which the hair shafts were suspended, indicating that (1)O(2) is generated and suppressed inside the hair structure. Both eumelanin and pheomelanin were shown to produce and to suppress (1)O(2), with similar efficiencies. The higher amount of (1)O(2) generated in blond hair and its longer lifetime is compatible with the stronger damage that light exposure causes in blond hair. We propose a model to explain the formation and suppression of (1)O(2) in hair by photosensitization of melanin with visible light and the deleterious effects that an excess of visible light may cause in hair and skin. 2011 Published by Elsevier Inc.

Lithium Ion Electro-Insertion and Spectroelectrochemical Properties of Films from Hexaniobate

Layer-by-layer (LbL) films from K(2)Nb(6)O(17)(2-) and polyallylamine (PAH) and dip-coating films of H(2)K(2)Nb(6)O(17) were prepared on a fluorine-doped tin-oxide (FTO)-coated glass. The atomic force microscopy (AFM) images were carried out for morphological characterization of both materials. The real surface area and the roughness factor were determined on the basis of pseudocapacitive processes involved in the electroreduction/electrooxidation of gold layers deposited on these films. Next, lithium ion insertion into these materials was examined by means of electrochemical and spectroelectrochemical measurements. More specifically, cyclic voltammetry and current pulses under visible light beams were used to investigate mass transport and chromogenic properties. The lithium ion diffusion coefficient (D(Li)) within the LbL matrix is significantly higher than that within the dip-coating film, ensuring high storage capacity of lithium ions in the self-assembled electrode. Contrary to the LbL film, the potentiodynamic profile of absorbance change (Delta A) as a function of time is not similar to that obtained in the case of current density for the dip-coating film. Aiming at analyzing the rate of the coloration front associated with lithium ion diffusion, a spectroelectrochemical method based on the galvanostatic intermittent titration technique (GITT) was employed so as to determine the ""optical"" diffusion coefficient (D(op)). In the dip-coating film, the method employed here revealed that the lithium ion rate is higher in diffusion pathways formed from K(2)Nb(6)O(17)(2-) sites that contribute more significantly to Delta A. Meanwhile, the presence of PAH contributed to the increased ionic mobility in diffusion pathways in the LbL film, with low contribution to the electrochromic efficiency. These results aided a better understanding of the potentiodynamic profile of the temporal change of absorbance and current density during the insertion/deinsertion of lithium ions into the electrochromic materials.