Guanylate cyclase inhibition by methylene blue as an option in the treatment of vasoplegia after a severe burn. A medical hypothesis

Today it is known that severe burns can be accompanied by the phenomenon of vasoplegic syndrome (VS), which is manifested by persistent and diffuse vasodilation, hypotension and low vascular resistance, resulting in circulatory and respiratory failure. The decrease in systemic vascular resistance observed in VS is associated with excessive production of nitric oxide (NO). In the last 2 decades, studies have reported promising results from the administration of an NO competitor, methylene blue (MB), which is an inhibitor of the soluble guanylate cyclase (sGC), in the treatment of refractory cases of vasoplegia. This medical hypothesis rationale is focused on the tripod of burns/vasoplegia catecholamine resistant/methylene blue. This article has 3 main objectives: 1) to study the guanylate cyclase inhibition by MB in burns; 2) to suggest MB as a viable, safe and useful co-adjuvant therapeutic tool of fluid resuscitation, and; 3) to suggest MB as burns hypotensive vasoplegia amine-resistant treatment.

Vesicle and Stable Monolayer Formation from Simple ``Click'' Chemistry Adducts in Water

Click chemistry has been successfully extended into the field of molecular design of novel amphiphatic adducts. After their syntheses and characterizations, we have studied their aggregation properties in aqueous medium. Each of these adducts forms stable suspensions in water. These suspensions have been characterized by dynamic light scattering (DLS) studies and transmission electron microscopy (TEM). The presence of inner aqueous compartments in such aggregates has been demonstrated using dye (methylene blue) entrapment studies. These aggregates have been further characterized using X-ray diffraction (XRD), which indicates the existence of bilayer structures in them. Therefore, the resulting aggregates could be described as vesicles. The temperature-induced order-to-disorder transitions of the vesicular aggregates and the accompanying changes in their packing and hydration have been examined using high-sensitivity differential scanning calorimetry, fluorescence anisotropy, and generalized polarization measurements using appropriate membrane-soluble probe, 1,6-diphenylhexatriene, and Paldan, respectively. The findings of these studies are consistent with each other in terms of the apparent phase transition temperatures. Langmuir monolayer studies confirmed that these click adducts also form stable monolayers on buffered aqueous subphase at the air-water interface.

Novel photocatalyst-based colourimetric indicator for oxygen: Use of a platinum catalyst for controlling response times

The preparation and characterisation of a novel, UV-activated, solvent-based, colourimetric indicator for oxygen is described, comprising a redox dye (methylene blue, MB), semiconductor photocatalyst (Pt-TiO2), and a sacrificial electron donor (SED = glycerol), all dispersed/dissolved in a polymer medium (sulfonated polystyrene. SPS). Upon exposure to UVA light, the Pt-TiO2/MB/glycerol/SPS oxygen indicator is readily photobleached as the MB is converted into its oxygen-sensitive, leuco form, LMB. In contrast to its non-platinised TiO2 counterpart (TiO2/MB/glycerol/SPS oxygen indicator), the recovery of the original colour is faster (ca. 1.5 days cf. 5 days at 21 degrees C). This is due to the catalytic action of the 0.38 wt% platinum loaded onto the semiconductor photocatalyst. TiO2, on the oxidation of the photogenerated LMB by ambient O-2. Furthermore, by increasing the level of platinum loading, recovery times can be decreased further; e.g. a Pt-TiO2/MB/glycerol/SPS oxygen indicator with platinum level of 1.52 wt% recovers fully within 12 h. A study of the kinetics of recovery as a function of film thickness revealed the recovery step is not controlled by the diffusion of O-2 through the film, but instead dependent upon the slow rate of oxidation of LMB to MB by O-2 in the low dielectric polymer encapsulation medium. Other work showed this recovery is only moderately dependant upon temperatures above -10 degrees C and very sensitive to relative humidity above 30% RH. Potential uses of this UV light activated indicator are discussed briefly. (C) 2011 Elsevier B.V. All rights reserved.

Novel photocatalyst-based colourimetric indicator for oxygen

The preparation and characterisation of a novel, UV-activated solvent-based, colourimetric indicator for O-2 is described, comprising a redox dye (methylene blue, MB), semiconductor photocatalyst (TiO2), and a sacrificial electron donor (SED), all dispersed/dissolved in a polymer medium (sulfonated polystyrene, SPS). Upon exposure, the indicator is readily photobleached as the MB is converted into its oxygen-sensitive, leuco form, LMB. Unlike its water-based counterpart, the recovery of the original colour is very slow (ca. 5 days cf. 6 min), probably due to the largely hydrophobic nature of the polymer encapsulation medium. The kinetics of film photobleaching appear to fit very well, in terms of: irradiance, [TiO2] and [MB], to the usual Langmuir-Hinshelwood type equation associated with a photocatalytic process. The glycerol appears not only to function as a SED, but also a plasticizer and medium for dye dissolution. The kinetics of colour recovery of the photobleached film appear directly dependent upon the ambient level of O-2 but shows a more complex dependence upon the relative humidity, RH. The photobleached film does not recover any of its colour over a 24 h period if the RH

Nanocrystalline SnO2-based, UVB-activated, colourimetric oxygen indicator

Nanocrystalline SnO2, ncSnO(2), is used as a photosensitiser in a colourimetric O-2 indicator that comprises a sacrificial electron donor, glycerol, a redox dye, methylene blue (MB), and an encapsulating polymer, hydroxyethyl cellulose (HEC). Upon exposure to a burst of UVB light the indicator is activated (photo-bleached) as the MB is photoreduced by the ncSnO(2) particles. In the absence of oxygen, the film stays bleached, but recovers its original colour upon exposure to oxygen. Unlike its TiO2-based predecessor, the HEC/glycerol/MB/ncSnO(2) O-2 indicator is not activated by UVA light from white fluorescent lamps, but is by UVB light. This feature provides much greater control in the activation of the indicator. Other work shows the rate of activation depends upon I-0.75, where I is the UVB irradiance, indicating a partial dependence upon the electron-hole recombination process. The half-life of the recovery of the original colour of a UV-activated film, t(50), is directly proportional to the ambient level of oxygen. The advantages of using this indicator in modified atmosphere packaging as a possible quality assurance indicator are discussed briefly. (c) 2008 Elsevier B.V. All rights reserved.

Efeito in vitro da terapia fotodinâmica sobre bactérias orais em suspensão e na formação de biofilme : ensaio com azul de metileno e toluidina ativados por luz halógena

Photodynamic therapy (PDT) has been proposed as an alternative method for the treatment of biofilm-dependent oral diseases like dental caries. This therapy consists of simultaneous action of a visible light (L) and a photosensitizer (FS) in the presence of oxygen, which leads to production of different reactive oxygen species that can interact with the bacterial cell components, and promote cell death. This study aims to evaluate the antimicrobial action of PDT on oral bacteria in suspension, as well as the formation of mono and multi-species biofilms, in vitro, from a standard strain of Streptococcus mutans (ATCC 25175) and saliva samples, respectively. The dye methylene blue (MB) and toluidine blue (TB) were used at a concentration of 100 mg/ L and activated by halogen light (600 to 750 nm) from a modified hand held photopolymerizer (Ultralux ®, Dabi Atlante, Ribeirão Preto , São Paulo, Brazil.). Planktonic cultures were prepared and submitted to different experimental conditions: 1. PDT using TB 2. PDT using MB, 3. L+ FS- , 4. TB + L - ; 5. MB+ L-; 6. L- FS- (negative control) and 7. administration of 0.12% chlorhexidine digluconate (positive control) (Periogard ®, Colgate-Palmolive Company, New York, USA). The immediate and mediated action of PDT on bacterial suspensions, as well as its effect on biofilm formation were observed from the number of colony-forming units per milliliter (CFU/mL) and measures optical density (OD). The data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney test for the significance level of 5%. According to the results, the PDT showed no antibacterial action on suspensions of S. mutans, regardless of the dye used. PDT with MB activated by halogen light was able to reduce 86.6% CFU/mL multi-species planktonic cultures, however, this reduction was not significant (p > 0.05). PDT showed antibacterial effect, mediate on multi-species planktonic cultures with TB (p < 0.001) and MB (p < 0.001), activated by halogen light. PDT was able to prevent the formation of multispecies biofilm, through the activation of TB by halogen light (p = 0.01). We conclude that activation of the dye toluidine blue and methylene blue, by halogen light (PDT) showed antimicrobial activity, compared to multi-species planktonic cultures prepared from saliva samples

Fenton-like processes and adsorption using iron oxide-pillared clay with magnetic properties for organic compound mitigation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Coating of surfaces of composite materials with enzymatically formed biosilica

Die Bildung kieselsäurehaltiger Spicula in marinen Schwämmen ist nur möglich durch die enzymatische Aktivität des Silicatein- in Verbindung mit der stöchiometrischen Selbstassemblierung des Enzyms mit anderen Schwammproteinen. Die vorliegende Arbeit basiert auf einem biomimetischen Ansatz mit dem Ziel, unterschiedliche Oberflächen für biotechnologische und biomedizinische Anwendungen mit Biosilica und Biotitania zu beschichten und zu funktionalisieren. Für biotechnologische Anwendungen ist dabei das Drucken von Cystein-getaggtem Silicatein auf Gold-Oberflächen von Bedeutung, denn es ermöglichte die Bildung definierter Biotitania-Strukturen (Anatas), welche als Photokatalysator den Abbau eines organischen Farbstoffs bewirkten. Des Weiteren zeigte sich die bio-inspirierte Modifikation von Tyrosin-Resten an rekombinantem Silicatein-(via Tyrosinase) als vielversprechendes Werkzeug zur Beschleunigung der Selbstassemblierung des Enzyms zu mesoskaligen Filamenten. Durch eine solche Modifikation konnte Silicatein auch auf der Oberfläche von anorganischen Partikeln immobilisiert werden, welches die Assemblierung von anorganisch-organischen Verbundwerkstoffen in wäßriger Umgebung förderte. Die resultierenden supramolekularen Strukturen könnten dabei in bio-inspirierten und biotechnologischen Anwendungen genutzt werden. Weiterhin wurde in der vorliegenden Arbeit die Sekundärstruktur von rekombinantem Silicatein- (Monomer und Oligomer) durch Raman Spektroskopie analysiert, nachdem das Protein gemäß einer neu etablierten Methode rückgefaltet worden war. Diese Spektraldaten zeigten insbesondere Änderungen der Proteinkonformation durch Solubilisierung und Oligomerisierung des Enzyms. Außerdem wurden die osteoinduzierenden und osteogenen Eigenschaften unterschiedlicher organischer Polymere, die herkömmlich als Knochenersatzmaterial genutzt werden, durch Oberflächenmodifikation mit Silicatein/Biosilica verbessert: Die bei der Kultivierung knochenbildender Zellen auf derart oberflächenbehandelten Materialien beobachtete verstärkte Biomineralisierung, Aktivierung der Alkalischen Phosphatase, und Ausbildung eines typischen zellulären Phänotyps verdeutlichen das Potential von Silicatein/Biosilica für der Herstellung neuartiger Implantat- und Knochenersatzmaterialien.

Características estruturais e fotocatalíticas do compósito oxihidróxido de nióbio/vermiculita

The preparation of nanostructured materials using natural clays as support, has been studied in literature under the same are found in nature and consequently, have a low price. Generally, clays serve as supports for metal oxides by increasing the number of active sites present on the surface and can be applied for various purposes such as adsorption, catalysis and photocatalysis. Some of the materials that are currently highlighted are niobium compounds, in particular, its oxides, by its characteristics such as high acidity, rigidity, water insolubility, oxidative and photocatalytic properties. In this scenario, the study aimed preparing a composite material oxyhydroxide niobium (NbO2OH) / sodium vermiculite clay and evaluate its effectiveness with respect to the natural clay (V0) and NbO2OH. The composite was prepared by precipitation-deposition method and then characterized by X-ray diffraction, infrared spectroscopy (XRD), energy dispersive X-ray (EDS), thermal analysis (TG/DTG), scanning electron microscopy (SEM), N2 adsorption-desorption and investigation of distribution of load. The application of the material NbO2OH/V0 was divided in two steps: first through oxidation and adsorption methods, and second through photocatalytic activity using solar irradiation. Studies of adsorption, oxidation and photocatalytic oxidation monitored the percentage of color removal from the dye methylene blue (MB) by UV-Vis spectroscopy. The XRD showed a decrease in reflection d (001) clay after modification; the FTIR indicated the presence of both the clay when the oxyhydroxide niobium to present bands in 1003 cm-1 related to Si-O stretching bands and 800 cm-1 to the Nb-O stretching. The presence of niobium was also confirmed by EDS indicated that 17 % by mass amount of the metal. Thermal analysis showed thermal stability of the composite at 217 °C and micrographs showed that there was a decrease in particle size. The investigation of the surface charge of NbO2OH/V0 found that the material exhibits a heterogeneous surface with average low and high negative charges. Adsorption tests showed that the composite NbO2OH/V0 higher adsorption capacity to remove 56 % of AM, while the material removed from V0 only 13 % showed no NbO2OH and adsorptive capacity due to the formation of H-aggregates. The percent removal of dye color for the oxidation tests showed little difference from the adsorption, being 18 and 66 % removal of dye color for V0 and NbO2OH/V0 respectively. The NbO2OH/V0 material shows excellent photocatalytic activity managing to remove just 95,5 % in 180 minutes of the color of MB compared to 41,4 % and 82,2 % of V0 the NbO2OH, proving the formation of a new composite with distinct properties of its precursors.

Síntese e caracterização de catalisadores baseados em vermiculita modificada com ferro: aplicação em processos do tipo foto-fenton

Clays are materials with specific properties that make them promising for various studies. In this work we used the vermiculite clay as support for iron compounds, in order to obtain promising materials for application in the heterogeneous type photo-Fenton process. In all, the study included six solid, starting from the vermiculite (V0) was obtained calcined vermiculite (V0-C), the mixed material (V0/β-FeOOH) formed by vermiculite more akaganeite, exchanged vermiculite (v0t-C), vermiculite impregnated Wet (V0u-C) and V0u-CL that is the solid obtained by impregnating with a back washing. The solids of the study had their physical and chemical characteristics investigated by the following characterization techniques: X-Ray Diffraction (XRD), Infrared Spectroscopy (IR), Energy Dispersive Spectroscopy (EDS), X-Ray Fluorescence Spectroscopy (XRF), UV-Vis by Diffuse Reflectance (DR UV-Vis), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). The V0 material showed three distinct phases, which are the very vermiculite, hidrobiotite and biotite, the last two phases are part of the geological of formation process vermiculite. The solids obtained after the modification showed an increase in the amount of iron present in the clay, these being quantities important for application in photocatalysis. The micrographs and EDS data, show that after treatment of addition of the metal , the iron was intercalary in structure of vermiculite for solid V0t-C and V0u-C, however, this did not occur with mixed material. In the photoFenton process, was observed a maximum removal of 88.8% of the dye methylene blue coloring for the catalyst V0/β-FeOOH, while for the other solids was obtained values between 76.8 and 62.6%, compared to 37.8% of discoloration without the presence of catalyst. Therefore, it is concluded that the vermiculite clay presents as a good catalyst and iron support for the, beyond of presenting a low cost because of its high abundance.

Comparative study on adsorption of two cationic dyes by milled sugarcane bagasse

Adsorptions of Rhodamine B (RhB) and Basic Blue 9 (BB9, also known as methylene blue) by sugarcane bagasse of different surface areas were compared in this study. There was a small gain in the amount of dye removed by increasing bagasse surface area from 0.57 m2/g to 1.81 m2/g. BB9 adsorption was less sensitive to surface area change than RhB adsorption. Adsorption capacity of 250 mg/L RhB on 1 g/L bagasse was 65.5 mg/g compared to a value of 30.7 mg/g obtained with BB9 under the same conditions. Increasing adsorption temperature (from 30 °C to 50 °C) while having no effect on RhB adsorption, slightly decreased BB9 adsorption by ~4%. The differences in adsorption performances between these dyes have been related to the molecular structure of the dyes and the surface chemistry of bagasse.