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1.
Int J Nanomedicine ; 15: 5803-5811, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32821102

RESUMO

Introduction: Photodynamic therapy (PDT), which induces tissue damage by exposing tissue to a specific wavelength of light in the presence of a photosensitizer and oxygen, is a promising alternative treatment that could be used as an adjunct to chemotherapy and surgery in oncology. Cell-penetrating peptides (CPPs) with high arginine content, such as protamine, have membrane translocation and lysosome localization activities. They have been used in an extensive range of drug delivery applications. Methods: We conjugated cell-penetrating peptides (CPPs) with methylene blue (MB) and then purification by FPLC. Synthesis structure was characterized by the absorbance spectrum, FPLC, Maldi-TOF, and then evaluated cell viability by cytotoxicity assay after photodynamic therapy (PDT) assay. An uptake imaging assay was used to determine the sites of MB and MB-Pro in subcellular compartments. Results: In vitro assays showed that MB-Pro has more efficient photodynamic activities than MB alone for the colon cancer cells, owing to lysosome rupture causing the rapid necrotic cell death. In this study, we coupled protamine with MB for high efficacy PDT. The conjugates localized in the lysosomes and enhanced the efficiency of PDT by inducing necrotic cell death, whereas PDT with non-coupled MB resulted in only apoptotic processes. Discussion: Our research aimed to enhance PDT by engineering the photosensitizers using CPPs coupled with methylene blue (MB). MB alone permeates through the cell membrane and distributes into the cytoplasm, whereas coupling of MB dye with CPPs localizes the MB through an endocytic mechanism to a specific organelle where the localized conjugates enhance the generation of reactive oxygen species (ROS) and induce cell damage.


Assuntos
Peptídeos Penetradores de Células/farmacologia , Azul de Metileno/farmacologia , Fotoquimioterapia , Apoptose/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Células HT29 , Humanos , Imageamento Tridimensional , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Azul de Metileno/química , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo
2.
Ecotoxicol Environ Saf ; 202: 110897, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32622307

RESUMO

Combining adsorption and photocatalysis is an effective strategy for degrading organic pollutants. Here, BiVO4@diatomite composite photocatalyst (BiVO4@diatomite CP) was prepared by hydrothermal synthesis from Bi(NO3)3·5H2O glycerin solution, NH4VO3 solution and diatomite. BiVO4@diatomite/microcrystalline cellulose/PVB composite fibers (BiVO4@diatomite/MCC/PVBCFs) were prepared from BiVO4@diatomite CPs, microcrystalline cellulose (MCC) and PVB ethanol solution using the electrospinning method. BiVO4@diatomite/MCC/PVBCFs were then mixed with pulp fibers to prepare the visible light-responsive photocatalytic paper. BiVO4@diatomite CP with a BiVO4/diatomite ratio of 6:4 had good interface states and displayed good photocatalytic activity with 64.32% degradation of methylene blue (MB) after 4 h. A PVB ethanol solution (6%) was formulated with BiVO4@diatomite CP and MCC to provide an ethanol spinning solution (12% solid) to prepare BiVO4@diatomite/MCC/PVBCFs (3:3:4). The resulting fibers had smooth surfaces, compact structures and exhibited good photocatalytic activity (66.80% and 56.80% degradation of MB and formaldehyde (HCHO), respectively, after 4 h). Photocatalytic paper containing 18% BiVO4@diatomite/MCC/PVBCFs had good photocatalytic activity with 50.20% degradation of HCHO after 4 h. This paper also had good physical properties and has the potential to be used for the photocatalytic degradation of indoor air pollutants, such as HCHO.


Assuntos
Poluentes Ambientais/química , Adsorção , Bismuto/química , Celulose , Terra de Diatomáceas , Luz , Azul de Metileno/química , Vanadatos/química
3.
Chemosphere ; 254: 126823, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334264

RESUMO

Environmentally toxic organic pollutants, namely methylene blue (MB), neutral red (NR), Rhodamine B (RhB), and methyl orange (MO) dyes contain highly toxic, carcinogenic, non-biodegradable, and colored pigments which cause harm for humans and aquatic organisms even at low concentrations. To detoxify these toxic organic pollutants from the wastewater, the bimetallic solid solution-typed In-Mo(O,S)2 catalyst with various indium (In) contents were synthesized at low temperature through a simple precipitation method. The morphological, structural, chemical compositions, electrochemical and optical properties of the catalysts were thoroughly characterized. The photodegradation performance of the In-Mo(O,S)2 catalysts over the cationic, anionic and neutral dyes were studied under visible light irradiation. It has been observed that the photocatalytic activity was enhanced as In was added to the Mo(O,S)2 catalyst, and In-Mo(O,S)2-20 was found to be the best composition to completely degrade four organic dyes. The dye degradation had rate constant values of 9.5 × 10-2 min-1, 6.3 × 10-2 min-1, 4.4 × 10-2 min-1, and 15.7 × 10-1 min-1 for MB (20 ppm), NR (20 ppm), RhB (10 ppm), and MO (10 ppm) dyes, respectively. The active species for degradation of MB is different from those for RhB and MO. Single phase In-Mo(O,S)2-20 capable to degrade four kinds of dyes at a fast rate is a good photocatalyst.


Assuntos
Corantes/análise , Poluentes Químicos da Água/análise , Compostos Azo , Catálise , Corantes/química , Índio , Luz , Azul de Metileno/química , Modelos Químicos , Fotólise , Rodaminas , Sulfetos , Águas Residuárias , Poluentes Químicos da Água/química
4.
Ecotoxicol Environ Saf ; 196: 110518, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32224367

RESUMO

Nano-sized Fe2Zr2-xWxO7 system was prepared using the Pacini method where x = 0, 0.05, 0.1 and 0.15. All the samples were characterized using chemical analysis, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance measurements (DRS) and surface area measurements. The undoped Fe2Zr2O7 was crystallised in the cubic fluorite phase as a major phase in addition to rhombohedral phase of Fe2O3 and monoclinic phase of ZrO2 as the minor phases. Meanwhile, single cubic fluorite phase was defined for Fe2Zr0.85W0.15O7 sample. The last has the lowest band gap (1.69 eV) and the highest surface area (106 m2/g). From TEM, the average particle size of the prepared samples was in the range of (3-7 nm). The photocatalytic efficiency of the prepared Fe2Zr2-xWxO7 system was manifested by the degradation of methylene blue and real textile wastewater of blue colour. Ascending degradation efficiency was exhibited with increasing tungsten concentration which is in accordance with their band gap as well as their surface area values. The degradation rate using Fe2Zr0.85W0.15O7 sample obeys the pseudo-first order kinetic at the optimum degradation conditions (1.5 g/L catalyst and pH11). Fe2Zr0.85W0.15O7 showed promising photocatalytic activity for real textile wastewater where the 69% COD removal was obtained under the same conditions used for methylene blue degradation.


Assuntos
Compostos Férricos/química , Luz , Azul de Metileno/análise , Nanopartículas/química , Óxidos/química , Tungstênio/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Zircônio/química , Catálise , Azul de Metileno/química , Azul de Metileno/efeitos da radiação , Tamanho da Partícula , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiação , Difração de Raios X
5.
Chemosphere ; 249: 126201, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32086067

RESUMO

Photoreaction with the Fe(III)-oxalate complex has been reported to play an important role in various photochemical reactions in the natural atmospheric environment, and are applicable to treat various recalcitrant compounds in wastewater. We previously showed that a Fe(II) oxalate (FeOx) crystal can be recovered from the wastewater generated from soil washing, which can then be applied to the photoreaction for degradation of recalcitrant pollutants; however, photoreactions with FeOx compounds have not been fully reported yet. Therefore, this study aims to investigate the photoreaction characteristics of FeOx recovered from wastewater, to demonstrate the feasibility of its application to wastewater treatment. The physical and chemical properties of FeOx were characterized with X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy analyses. The photoreaction of FeOx showed high methylene blue (MB) removal efficiencies similar to the reaction with TiO2, indicating that FeOx is applicable to the photoreaction for degradation of pollutants. Furthermore, the photodegradation of MB with FeOx was observed under visible light, as opposed to TiO2. MB could be removed by the photoreaction of FeOx under both basic and acidic pH conditions. Under basic pH conditions, MB could be removed by FeOx via both photoreaction and surface adsorption. The concentration of FeOx affected light penetration and Fe and oxalate levels in the solution, resulting in different MB removal kinetics. The photoreaction efficiency of FeOx could be affected by both photoreaction of Fe and oxalate in the solution and photoreaction and adsorption reaction of the FeOx surface.


Assuntos
Compostos Férricos/química , Processos Fotoquímicos , Poluentes Químicos da Água/química , Adsorção , Compostos Férricos/análise , Compostos de Ferro , Cinética , Luz , Azul de Metileno/química , Oxalatos , Fotólise , Águas Residuárias/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Difração de Raios X
6.
J Photochem Photobiol B ; 204: 111804, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32007677

RESUMO

The ubiquitous influence of double stranded RNAs in biological events makes them imperative to gather data based on specific binding procedure of small molecules to various RNA conformations. Particular interest may be attributed to situations wherein small molecules target RNAs altering their structures and causing functional modifications. The main focus of this study is to delve into the interactive pattern of two small molecule phenothiazinium dyes, methylene blue and new methylene blue, with three duplex RNA polynucleotides-poly(A).poly(U), poly(C).poly(G) and poly(I).poly(C) by spectroscopic and molecular modeling techniques. Analysis of data as per Scatchard and Benesi-Hildebrand methodologies revealed highest affinity of these dyes to poly(A).poly(U) and least to poly(I).poly(C). In addition to fluorescence quenching, viscometric studies also substantiated that the dyes follow different modes of binding to different RNA polynucleotides. Distortion in the RNA structures with induced optical activity in the otherwise optically inactive dye molecules was evidenced from circular dichroism results. Dye-induced RNA structural modification occurred from extended conformation to compact particles visualized by atomic force microscopy. Molecular docking results revealed different binding patterns of the dye molecules within the RNA duplexes. The novelty of the present work lies towards a new contribution of the phenothiazinium dyes in dysfunctioning double stranded RNAs, advancing our knowledge to their potential use as RNA targeted small molecules.


Assuntos
Azul de Metileno/análogos & derivados , Azul de Metileno/química , RNA de Cadeia Dupla/química , Sítios de Ligação , Corantes/química , Azul de Metileno/metabolismo , Microscopia de Força Atômica , Simulação de Acoplamento Molecular , Conformação de Ácido Nucleico , Fenotiazinas/química , Poli C/química , Poli C/metabolismo , Poli G/química , Poli G/metabolismo , RNA de Cadeia Dupla/metabolismo , Espectrometria de Fluorescência , Espectrofotometria , Viscosidade
7.
J Photochem Photobiol B ; 204: 111809, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32062390

RESUMO

The graphene oxide (GO)-based materials are appealing channels for water treatment, their separation from water for recycle remains a task. The Cu3(btc)2 (btc = benzene-1,3,5-tricarboxylic acid) metal organic framework (MOF) was covalently immobilized onto chitosan (CS)/graphene oxide (GO) to form a catalyst material, which was subjected to characterization by XRD, FTIR, SEM, TEM, BET, and UV-vis diffusive reflectance spectra. MOFs are permeable crystalline compounds consisting of metal ions and polyfunctional organic ligands. The structural characterization revealed that the Cu3(btc)2 and chitosan were incorporated into the graphene oxide structure. The adsorption of MB by GO-CS@Cu3(btc)2 catalyst was clearly defined by Langmuir isotherm and pseudosecond order kinetic model. GO-CS@Cu3(btc)2 was found to possess an adsorption capacity of ~357.15 mg/g. The findings displayed the probability of reusing the catalyst material for several photocatalytic processes. The GO-CS@Cu3(btc)2 catalyst material exhibited 98% degradation of MB within 60 min under UV irradiation. The obtained MB degradation results were fitted onto a Langmuir-Hinshelwood (L-H) plot. The GO-CS@Cu3(btc)2 catalyst material exhibited high degradation efficiencies at neutral pH conditions. The results have shown that the GO-CS@Cu3(btc)2 catalyst material can be used as a catalyst for adsorption and as a photocatalyst for the efficient degradation of methylene blue from aqueous solutions.


Assuntos
Quitosana/química , Complexos de Coordenação/química , Grafite/química , Azul de Metileno/química , Adsorção , Catálise , Cobre/química , Concentração de Íons de Hidrogênio , Cinética , Fotólise/efeitos da radiação , Raios Ultravioleta
8.
J Photochem Photobiol B ; 204: 111781, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31981989

RESUMO

In the recent years, copper tungstate (CuWO4) has been widely researched for its photocatalytic properties as it responds in the visible light range to augment the utilization of solar energy. In the present report, CuWO4 was synthesized through a facile and cost-effective solvothermal method, followed by annealing process at 700∘C. The structural, morphological, compositional and optical property of the synthesized powders were examined by X-ray diffraction, scanning electron microscope, UV-visible, Raman and photoluminescence studies. The photocatalytic activity of the nanostructured CuWO4 was evaluated by the degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution under one sun light irradiation. The degradation efficiency of MB was found to be about 70% while that of MO was only 57% at 240 min in the same irradiation time. Surprisingly, the degradation process was accelerated by the addition of electron capturing agent H2O2 and thus MB dye was completely degraded within the time interval of 30 min while MO degraded in 75 min. These results prove that CuWO4 nanoparticles possess significant photocatalytic activity towards MO and MB dyes, thus indicating the feasibility of using CuWO4 for the active treatment of organic contaminants in the industrial effluents.


Assuntos
Compostos Azo/química , Peróxido de Hidrogênio/química , Azul de Metileno/química , Luz Solar , Compostos de Tungstênio/química , Catálise , Cobre/química , Nanopartículas/química , Oxirredução , Fotólise/efeitos da radiação
9.
J Photochem Photobiol B ; 203: 111774, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931386

RESUMO

Zeolitic imidazole framework (ZIF) is an emerging class of metal organic frameworks exhibiting unique features such as crystalline nature with tunable pore size, large surface area and biocompatible nature. Exceptional thermal and chemical stabilities of ZIF-L make it a suitable candidate for biomedical applications. The present study has focused on the single step fabrication of catechin encapsulated ZIF-L and evaluation of its antibiofilm efficiency, larvicidal activity and dye degradation ability. The as- prepared CA@ZIF-L nanocomposite was characterized by spectroscopic and microscopic techniques. The results revealed that the CA@ZIF-L showed significant toxicity against mosquito larvae in a dose dependent manner with the IC50 63.43±1.25 µg/mL. CA@ZIF-L showed dose dependent reduction of biofilm formation in both ATCC and clinical MRSA strains. In addition, CA@ZIF-L exhibited excellent photocatalytic activity with around 92% degradation of methylene blue under direct sunlight. Overall, the present work highlights the possibility of employing the multifunctional CA@ZIF-L nanocomposite as a suitable material for biomedical and photocatalytic applications.


Assuntos
Biofilmes/efeitos dos fármacos , Catequina/química , Estruturas Metalorgânicas/química , Nanocompostos/toxicidade , Zeolitas/química , Animais , Catálise , Culicidae/efeitos dos fármacos , Culicidae/crescimento & desenvolvimento , Imidazóis/química , Larva/efeitos dos fármacos , Luz , Staphylococcus aureus Resistente à Meticilina/fisiologia , Azul de Metileno/química , Nanocompostos/química , Tamanho da Partícula , Fotólise/efeitos da radiação
10.
J Photochem Photobiol B ; 203: 111776, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931388

RESUMO

Due to the emergence of antibiotic resistance, antimicrobial photodynamic therapy (aPDT) has recently been demonstrated as a promising alternative to antibiotics to treat wound infections caused by multidrug-resistant (MDR) pathogens. This study aimed to evaluate the bacterial killing efficiency of aPDT mediated by methylene blue (MB) loaded thermosensitive hydrogels against methicillin-resistant Staphylococcus aureus (MRSA). Box-Behnken Design method was employed to investigate the impacts of the polymer compositions, Poloxamer 407, Poloxamer 188 and Carbopol 934P, on the gelation temperature (Tsol-gel) and release rate of MB. The viscosity and in vitro bacterial killing efficiency of three selected formulations with Tsol-gel ranged 25-34 °C and MB release in 2 h (the incubation time used for aPDT experiment) ≥ 70%, were assessed. The viscosity was found to increase with increasing P407 content and increasing total gel concentration. In the in vitro aPDT experiment, all tested MB-hydrogels demonstrated >2.5 log10 colony forming unit (CFU) reduction against three clinical relevant MRSA strains. Interestingly, the bacterial reduction increased with decreasing amount of gel added (reduced MB concentration). This was possibly attributed to the increased viscosity at higher gel concentration reducing the diffusion rate of released MB towards bacterial cells leading to reduced aPDT efficiency. In summary, aPDT with the thermosensitive MB hydrogel formulations is a promising treatment strategy for wound infections.


Assuntos
Anti-Infecciosos/química , Hidrogéis/química , Azul de Metileno/química , Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Luz , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Azul de Metileno/metabolismo , Azul de Metileno/farmacologia , Reologia , Temperatura , Viscosidade
11.
Chemosphere ; 246: 125755, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927368

RESUMO

Laser ablation in liquid (LAL), one of the attractive methods for fabrication of nanoparticles, was used for the modification of carbon cloth (CC) by deposition of palladium nanoparticles (Pd NPs); a simple stirring method was deployed to deposit Pd NPs on the CC surface. Characterization techniques viz X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) were applied to study the surface of the ensuing samples which confirmed that LAL technique managed to fabricate and deposit the Pd NPs on the surface of CC. In addition, the catalytic prowess of the carbon cloth-Pd NPs (CC/Pd NPs) was investigated in the NaBH4- or HCOOH-assisted reduction of assorted environmental pollutants in aqueous medium namely hexavalent chromium [Cr(VI)], 4-nitrophenol (4-NP), congo red (CR) and methylene blue (MB). The CC/Pd NPs system has advantages such as high stability/sustainability, high catalytic performance and easy reusability.


Assuntos
Nanopartículas Metálicas/química , Paládio/química , Poluentes Químicos da Água/química , Carbono , Catálise , Cromo , Vermelho Congo , Lasers , Azul de Metileno/química , Nitrofenóis , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Têxteis , Poluentes Químicos da Água/análise
12.
Chemosphere ; 243: 125334, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995864

RESUMO

Developing novel heterogeneous photo-Fenton catalysts with high efficiency and stability, driven by visible-light rather ultraviolet light at neutral pH has been a major challenge for degradation of organic pollutants. In this work, we successfully synthesized a metalloporphyrin-based porous organic polymer (FePPOP-1) by the Sonogashira cross-coupling reaction. UV-vis absorption spectra showed FePPOP-1 exhibits a significant coverage of the natural solar irradiance spectrum. As a result, the prepared FePPOP-1 has a significantly enhanced photocatalytic activity for the visible-light-driven degradation of methylene blue. By using only 4 mg of FePPOP-1 as a catalyst, it was found that 50 mL of organic wastewater containing 70 ppm MB could be totally degraded in 80 min even at neutral pH. The effects of the initial MB, H2O2 concentrations, pH value and common ions on MB degradation were studied in detail. Both the catalytic mechanism of FePPOP-1 and the degradation route of MB were also proposed.


Assuntos
Metaloporfirinas/química , Polímeros/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Catálise , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Ferro , Luz , Azul de Metileno/química , Compostos Orgânicos/química , Processos Fotoquímicos , Porosidade , Espectrofotometria Ultravioleta
13.
Artigo em Inglês | MEDLINE | ID: mdl-31947663

RESUMO

Adsorption in biomass has proven to be a cost-effective option for treatment of wastewater containing dyes and other pollutants, as it is a simple and low cost technique and does not require high initial investments. The present work aimed to study the adsorption of methylene blue dye (MB) using sugarcane bagasse (SCB). The biomass was characterized by scanning electron microscopy (SEM). Adsorption studies were conducted batchwise. Kinetics, adsorption isotherms, and thermodynamics were studied. The results showed that SCB presented a maximum adsorption capacity of 9.41 mg g-1 at 45 °C after 24 h of contact time. Adsorption kinetics data better fitted the pseudo-second order model, indicating a chemical process was involved. The Sips's three-parameter isotherm model was better for adjusting the data obtained for the adsorption isotherms, indicating a heterogeneous adsorption process. The process showed to be endothermic, spontaneous, and feasible. Therefore, it was concluded that SCB presented as a potential biosorbent material for the treatment of MB-contaminated waters.


Assuntos
Celulose/química , Azul de Metileno/química , Saccharum , Poluentes Químicos da Água/química , Adsorção , Biomassa , Corantes , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Termodinâmica , Águas Residuárias/química
14.
Chemosphere ; 243: 125344, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31756657

RESUMO

A facile ball-milling method was developed to synthesize MgO/biochar nanocomposites as a dual-functional adsorbent. The physicochemical properties of the synthesized nanocomposites indicated that the composites achieved nano-scaled morphologies and mesoporous structure with MgO nanoparticles, which is approximate 20 nm and dispersed uniformly on the surface of the biochar matrix. Batch sorption experiments yielded 62.9% removal of phosphate, an anion, and 87.5% removal of methylene blue, a cationic organic dye, at low adsorbent dosages of 1.0 g L-1 and 0.2 g L-1, respectively. This work indicates that ball milling, as a facile and promising method for synthesis of carbon-metal oxide nanocomposites, lends the advantage of operational flexibility and chemical adjustability for targeted remediation of diverse environmental pollutants.


Assuntos
Carvão Vegetal/química , Poluentes Ambientais/química , Óxido de Magnésio/química , Adsorção , Carbono/química , Corantes , Azul de Metileno/química , Nanocompostos , Óxidos , Fosfatos/química
15.
Chemosphere ; 241: 125020, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31614314

RESUMO

A nanocomposite of graphene and titanium dioxide (G/TiO2) was prepared using the sol-gel method for use in an electrochemical adsorption/regeneration process. The effect of annealing temperature on electrochemical characteristics of the nanocomposites was investigated by cyclic voltammetry and constant current electrochemical regeneration, using methylene blue (MB) as the adsorbate. The G/TiO2 could be regenerated more rapidly and with less corrosion than the bare graphene. The G/TiO2 annealed at 400 °C had a higher proportion of anatase phase TiO2 (ca. 7% rutile TiO2) compared to that annealed at 500 °C (ca. 40% rutile TiO2). Cyclic voltammetry indicated that the G/TiO2 annealed at 400 °C had a higher activity for MB oxidation than the nanocomposite annealed at 500 °C. Similarly, the regeneration of MB loaded G/TiO2 annealed at 400 °C was much faster than for the nanocomposite annealed at 500 °C. Complete regeneration of the G/TiO2 annealed at 400 °C was obtained after an electrochemical charge of 21 C per mg of adsorbate. The G/TiO2 annealed at 400 °C was regenerated in half the time required for the bare graphene. TEM studies showed that the bare graphene was rapidly corroded, while corrosion was not observed for the G/TiO2 nanocomposites.


Assuntos
Corantes/química , Técnicas Eletroquímicas/métodos , Grafite , Nanocompostos/química , Reciclagem/métodos , Titânio , Adsorção , Corrosão , Eletrodos , Azul de Metileno/química
16.
Environ Sci Pollut Res Int ; 27(1): 1053-1068, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31814075

RESUMO

Dyes are colored compounds which are visible even at trace concentrations. Due to their recalcitrance and esthetic persistence, certain methods are unable to effectively eliminate them. So far, adsorptive treatment using activated carbons (ACs) is one of the most successful methods. In this study, we have employed orange peel (OP) as a cost-effective alternative to the expensive coal- and coir-based precursors to synthesize ACs for cationic methylene blue (MB) and anionic methyl orange (MO) dye adsorption. The pre-carbonized OP was activated via H2SO4, NaOH, KOH, ZnCl2, and H3PO4 to study the effects of activation reagents on dye removal efficiencies and mechanisms. Among several isotherm models employed to fit the adsorption data, the Langmuir and Sips models sufficiently estimated the maximum equilibrium uptakes close to the experimental values of 1012.10 ± 29.13, 339.82 ± 6.98, and 382.15 ± 8.62 mg/g, for ZnCl2-AC (MO), ZnCl2-AC (MB), and KOH-AC (MB), respectively. The adsorption mechanisms were suggested to involve electrostatic binding, pi-pi interactions, hydrogen bonding, and electron donor-acceptor reactions. Consequently, more than 99% removal efficiency was achieved from a laboratory organic wastewater sample bearing ~ 35 mg/L of MB. The results thus suggest that the synthesized ACs from agricultural waste have the tendencies to be applied to real dye wastewater treatment.


Assuntos
Carvão Vegetal/química , Corantes/química , Azul de Metileno/química , Adsorção , Agricultura , Compostos Azo , Citrus sinensis , Cinética , Águas Residuárias , Poluentes Químicos da Água/química
17.
Lasers Med Sci ; 35(1): 79-85, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31081523

RESUMO

Chagas disease is endemic in Latin America and increasingly found in non-endemic countries. Its treatment is limited due to the variable efficacy and several side effects of benznidazole. Photodynamic antimicrobial chemotherapy (PACT) may be an attractive approach for treating Chagas disease. Here, the trypanocidal activity of PACT was investigated in vitro using phenothiazine derivatives. The cytotoxicity of both, methylene blue (MB) and toluidine blue (TBO), was determined on macrophages cultures using AlamarBlue method. The trypanocidal activity of the two photosensitizers was initially evaluated by determining their IC50 values against trypomastigote forms. After this, the trypanocidal effect was evaluated in cultures of infected macrophages using an automatized image analysis protocol. All experiments were performed in the dark and in the clear phase (after a photodynamic exposure). The compounds showed no cytotoxicity in both phases at the tested concentrations. The IC50 values for the sole use of MB and TBO were 2.6 and 1.2 µM, respectively. The photoactivation of the compounds using a fixed energy density (J/cm2) caused a reduction of the IC50 values to 1.0 and 0.9 µM, respectively. It was found that, on infected macrophage, the use of TBO significantly reduced the number of infected cells and parasitic load, and this effect was increased in the presence of light. The results of the present study are indicative that PACT may be considered as both selective and effective therapeutic intervention for treating Chagas disease.


Assuntos
Antiparasitários/farmacologia , Fenotiazinas/farmacologia , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Anti-Infecciosos/farmacologia , Antiparasitários/uso terapêutico , Morte Celular/efeitos dos fármacos , Morte Celular/efeitos da radiação , Doença de Chagas/tratamento farmacológico , Humanos , Luz , Azul de Metileno/química , Azul de Metileno/farmacologia , Azul de Metileno/uso terapêutico , Camundongos Endogâmicos BALB C , Carga Parasitária , Fenotiazinas/uso terapêutico , Fármacos Fotossensibilizantes/uso terapêutico , Cloreto de Tolônio/química , Cloreto de Tolônio/farmacologia , Cloreto de Tolônio/uso terapêutico , Trypanosoma cruzi/efeitos da radiação
18.
Chemosphere ; 241: 125021, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683448

RESUMO

The magnetic composite CoFe2O4/ZIF-8 based on metal organic framework (MOF) with high specific surface area and high activity was synthesized by solvothermal method. The prepared catalysts were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), vibration sample magnetometer (VSM) and N2 adsorption-desorption isotherms, respectively. After characterization, CoFe2O4/ZIF-8 was applied to heterogeneous activation of peroxymonosulfate (PMS) for degrading methylene blue (MB). The result showed that the 0.075-CoFe2O4/ZIF-8 sample had the excellent catalytic activity. After catalytic reaction for 60 min, the degradation efficiency of MB (20 mg/L) reached about 97.9% at room temperature of 20 °C. The quenching experiment and electron paramagnetic resonance (EPR) analysis indicated that SO4- and OH radicals were the main active species in MB degradation. Meanwhile, the possible MB degradation mechanism was proposed. After four catalytic cycles, the degradation efficiency of MB has not been greatly reduced, indicating the practical application potential of CoFe2O4/ZIF-8 in water pollution cleanup.


Assuntos
Cobalto/química , Corantes/química , Compostos Férricos/química , Estruturas Metalorgânicas/química , Peróxidos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Catálise , Compostos Férricos/síntese química , Magnetismo , Azul de Metileno/química
19.
Chemosphere ; 241: 124981, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31606579

RESUMO

Photocatalytic degradation of toxic pollutants is an efficient technique to completely remove the toxic pollutants from water bodies. In the present investigation, photocatalytic degradation of pollutants was studied over porous g-C3N4/H-ZSM-5 nanocomposite under visible light irradiation. The composite g-C3N4/H-ZSM-5 was synthesized by mixing an aqueous solution of H-ZSM-5 zeolite (increases surface area and provides active sites for degradation) with melamine (precursor of g-C3N4) for 10-12 h followed by calcinations at 550 °C. The photocatalyst was characterized by XRD, BET, HRTEM, FESEM, EDS and elemental mapping analysis. These techniques confirmed that, g-C3N4/H-ZSM-5 composite have layered and porous structure with uniform distribution of g-C3N4 on H-ZSM-5 surface. The BET N2 adsorption-desorption analysis verified that the catalyst has high surface area (∼175 m2/g) having mesopores and micropores. The prepared catalyst was then used for the photodegradation of a model dye, Methylene Blue (MB) and an endocrine disrupting compound, Fipronil (FIP). Effects of various parameters such as pH, catalyst dose and scavengers were also studied. The % photocatalytic degradation of MB and FIP were around ∼92% and ∼84% with a high rate constants of 0.00997 and 0.00875 min-1, respectively. From the scavenger study, OH (hydroxyl radical) and radical was found to be the major reactive species for MB and FIP degradation. From these studies it is revealed that, the catalyst is visible active, easy to prepare and an efficient photocatalyst for toxic pollutant degradation.


Assuntos
Disruptores Endócrinos/química , Luz , Nanocompostos/química , Fotólise , Zeolitas/química , Adsorção , Catálise , Disruptores Endócrinos/efeitos da radiação , Azul de Metileno/química , Microscopia Eletrônica de Transmissão , Porosidade
20.
Mater Sci Eng C Mater Biol Appl ; 107: 110309, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761185

RESUMO

Release behaviors of drugs from drug deliveries are crucial for the enhancement of therapy efficiency, reduction of toxicity and patient compliance. Herein, antisolvent crystallization is employed to coat methlyene blue (MB)-loaded silica by shellac precipitation (silica-MB@shellac), which is simultaneously induced by outward diffusion of H+ ions from particular silica-MB. The encapsulation of shellac shell on silica-MB modulates the aggregation state of MB, which endows silica-MB@shellac a decreased MB's thermal stability, enhanced photoluminescence intensity, improved stability against in vitro reduction by ascorbic acid and retained photodynamic therapy activity. From the absorbance of MB supernatant obtained during incubation, the concentrations of MB monomers and dimers are determined via a non-linear regression analysis to investigate the influence of shellac coating on MB's release mechanisms from silica-MB@shellac. According to the simulated models, small diffusion constants of MB are caused by limited diffusion through shellac shells with high compaction degrees. These are observed for samples synthesized under high supersaturation degree during antisolvent crystallization. High degree of supersaturation is achieved through increasing shellac concentration, additive amount and dropping rate of antisolvent, as well as decreasing pH values of aqueous buffers as antisolvent. Furthermore, a combined mechanism of Fickian diffusion and Case-IΙ relaxation is proposed to describe the release behaviors of MB monomer and dimers from silica-MB@shellac. Therefore, this work may shed light on the encapsulation method of polymer on drug-loaded powders and the control of aggregation states of photosensitizers to promote the photoluminescence intensity, photodynamic therapy efficiency and controlled release behaviors.


Assuntos
Azul de Metileno/química , Azul de Metileno/farmacocinética , Fármacos Fotossensibilizantes/química , Resinas Vegetais/química , Dióxido de Silício/química , Cristalização , Concentração de Íons de Hidrogênio , Cinética , Teste de Materiais , Fotoquimioterapia
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