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<i>Candida albicans</i> Sterilization Using a Light-Emitting Diode and Methylene Blue
摘要： Background and aims: Conventional fungal treatment using external medication requires considerable time and effort. We herein examined the basic effect of methylene blue (MB) with sodium bicarbonate (NaHCO3) on Candida albicans sterilization using photodynamic antimicrobial chemotherapy (PACT). Materials and methods: NaHCO3 was added to MB to establish a basic pH. Then, C. albicans was smeared on a medium with basic MB followed by irradiation using a red light-emitting diode (LED) with a wavelength of 660 nm. The applied energy fluencies were 5, 10, 15, and 20 J/cm2. After 48 h of culture, the effects of the intervention were determined according to the fungal growth area. Results: The basic effect appeared at a pH range of 8.6 to 8.9 and at 10 and 15 J/cm2, while the NaHCO3 concentration was between 1% and 2%. Conclusions: Our results suggested that PACT using basic MB was effective for C. albicans sterilization.
关键词： C. albicans,basic effect,methylene blue,LED,PACT,sodium bicarbonate
更新于2025-09-11 14:15:04
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Enhanced sunlight photocatalytic degradation of methylene blue by rod-like ZnO-SiO2 nanocomposite
摘要： This work aims to develop a novel and economical rod-like zinc oxide–silicon dioxide (ZS) nanocomposite by a simple co-precipitation method with different surfactants, such as cationic surfactant cetyl triethylammonium bromide (CTAB), non-ionic polymer polyvinyl pyrrolidone (PVP), and an anionic surfactant sodium dodecyl sulfate (SDS). The phase identification, surface topography and optical properties were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV-Visible and Photoluminescence Spectroscopy. The photocatalytic degradation efficiency of the prepared nanocomposite was measured using model organic pollutant of methylene blue (MB) in water under sun light irradiation. Due to surface plasmon resonance (SPR) effect of SiO2 nanoparticles, ZS nanocomposite shows an absorption peak (434 nm) in the visible region. Hence the maximal MB degradation efficiency of 97.8% was achieved under 90 min of sunlight irradiation. Among the three surface-active agents, cationic surfactant shows the highest degradation ability with ZS nanocomposite. This work will open a new platform for further development of ZS-based nanocomposites to solve the global photocatalytic and waste water treatment problem.
关键词： ZnO–SiO2,Co-precipitation,Sun light,Surfactant,Methylene blue
更新于2025-09-11 14:15:04
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Sunlight driven highly efficient degradation of methylene blue by CuO-ZnO nanoflowers
摘要： Highly efficient photocatalysis of methylene blue dye has been demonstrated using hierarchical copper oxide and zinc oxide (CuO-ZnO) nanoflower like structure. The flower like nanostructures are obtained using polyethylene glycol and sodium citrate with facile single step hydrothermal method. The effect of different operating parameters viz. effect of OH- ion concentration, metal ion precursor and synthesis method on typical morphology of the CuO-ZnO product has been studied in detail. The synthesized samples were characterized by various techniques and were then used in sunlight driven degradation of methylene blue dye. The photocatalytic performance of selected CuO-ZnO product (sample CZ-01) demonstrated the best photocatalytic activity under sunlight irradiation with rate constant of approximately 0.099 min-1. The superior photocatalytic performance of CuO-ZnO was attributed to suppressed charge-carrier recombination. Methylene blue dye (100 mL of 100 ppm) was observed to be completely degraded in 30 minutes with CuO-ZnO (sample CZ-01) hierarchical nanostructure as catalyst.
关键词： ZnO,Methylene blue (MB),CuO,CuO-ZnO,photocatalysis
更新于2025-09-11 14:15:04
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Photodegradation of Methylene Blue by a ternary magnetic TiO2/Fe3O4/Graphene oxide nanocomposite under visible light
摘要： In this study, a facile hydrolysis method was employed for the synthesis of magnetic TiO2/Fe3O4/Graphene oxide nanocomposites with different amounts of graphene oxide (0.015, 0.03, 0.06, and 0.12 gr), which can be easily separated by application of an external magnetic field. The prepared nanocomposites were evaluated using XRD, FTIR, FESEM/EDX, TEM and UV-Vis DRS techniques. Morphological characterization showed that size of TiO2 nanoparticles (NPs) and Fe3O4 NPs is nearly 6.0-7.0 nm 27.81 nm, respectively, and they both are coated on the surfaces of graphene oxide. XRD results indicated the presence of anatase TiO2 and inverse cubic spinel Fe3O4 in the nanocomposite structure. Photoactivity of the synthesized nanocomposites in degradation of methylene blue (MB) was investigated by UV irradiation and visible light. According to the results, ternary nanocomposite containing 0.12 gr of graphene oxide can provide the highest photocatalytic MB degradation. Degradation percentages (DP%) of ~ 82% under UV irradiant and 76% under visible light were achieved after 90 min irradiation. Therefore, it is possible to use TiO2/Fe3O4/GO nanocomposite in the photodegradation of MB and other organic pollutants owing to its noticeable visible light-induced photocatalytic performance and also magnetic properties (which help their recycle).
关键词： Degradation,Methylene blue,Graphene oxide,TiO2,Fe3O4
更新于2025-09-11 14:15:04
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Applications of polystyrene/graphite composites in water purification as a semiconductor visible-light photocatalyst for organic pollutant degradation
摘要： The aim of this study was to prepare a polymer/graphite composite thin film as a cheap, and nontoxic photocatalyst that could be activated by visible light. It was characterized using ultraviolet/visible spectrophotometry and X-ray diffraction. Scanning electron microscopy was used to examine the photocatalyst surface before and after a photodegradation process. The photocatalyst showed activity under visible light and was used for the photodegradation of methylene blue (MB) and rhodamine B (Rh-B) as target pollutants. The process was studied with different pH values, initial dye concentrations, and light intensities from the radiation source to evaluate their effects. The results revealed that the photodegradation was affected by the initial dye concentration, and also showed that the best conditions for the photodegradation reactions of both dyes were an alkaline medium and a light intensity of 80 wt. The films prepared under the conditions reported herein could be promising materials in water purification.
关键词： Rhodamine B,Methylene blue,Photocatalyst,Photodegradation
更新于2025-09-10 09:29:36
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Nigella sativa seed based nanocomposite-MnO2/BC: An antibacterial material for photocatalytic degradation, and adsorptive removal of dye from water
摘要： Antimicrobial Nigella sativa seed-based nanocomposite, MnO2/BC, was synthesized and utilized for water purification through adsorption and photocatalytic degradation. MnO2/BC was prepared by co-precipitation method, and characterized using FT-IR, XRD, SEM, TEM, TGA, and DSC techniques. The composite was investigated for inhibition of bacterial cells growth. FT-IR spectrum indicated the presence of oxygenous groups on the surface; TGA and DSC showed thermal degradation; and XRD, SEM, and TEM investigations indicated amorphous, and porous nature of MnO2/BC having particle size of 190-220 nm. The nanocomposite inhibited the growth of both Gram-positive and Gram-negative bacteria cells in water. The adsorption of Methylene blue (MB) from water was investigated in batch method in terms of amount of MnO2/BC, MB concentration, pH, time, and temperature. 1.0 gL-1 of MnO2/BC removed more than 98% of MB from aqueous solution having concentration of 10 mgL-1 and pH 7.0 at 27°C. The maximum Langmuir adsorption capacity of MnO2/BC was 185.185 mgg-1 at 45°C. The adsorption was an endothermic process which obeyed Freundlich isotherm, and pseudo-second order kinetics. Therefore, the MB binding onto MnO2/BC surface was site-specific partially through weak hydrogen bonding and electrostatic interactions. The photocatalytic activity of MnO2/BC has been investigated by degrading the MB molecules/ions in water under the sunlight and 85% of degradation was achieved during 120 min irradiation. The dye was desorbed at lower pH and regenerated MnO2/BC was used for second cycle of MB adsorption. The results obtained for this study are much better than the previous MB adsorption studies with acid washed Black cumin seeds and MnFe2O4/BC for which the capacities were 73.529 mgg-1 and 10.070 mgg-1 at 27°C, respectively (J. Mol. liq. 2018a, 264, 275-284; J. Clean. Prod. 2018a, 200, 996-1008).
关键词： MnO2/BC,Antibacterial activity,Photocatalytic degradation,Adsorption,Nigella sativa plant seeds,Methylene blue
更新于2025-09-10 09:29:36
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Transformation pathway and degradation mechanism of methylene blue through β-FeOOH@GO catalyzed photo-Fenton-like system
摘要： To enhance the catalytic and separation properties of akaganéite nanoparticles, rice spike-like akaganéite impregnated graphene oxide (β-FeOOH@GO) nanocomposite was fabricated through facile hydrolysis. The apparent first-order decolorization rate of methylene blue (MB) in β-FeOOH@GO catalyzed photo Fenton-like system was 0.6322 min-1 about 3 folds that of prinstine β-FeOOH nanoparticles. The degradation intermediates of MB adsorbed on the solid surface of β-FeOOH@GO were comprehensively identified with time of flight-secondary ion mass spectroscopy (TOF-SIMS) for the first time. Newly identified sulfoxide intermediates, sulphone intermediates and desulfurization intermediates and N-demethylaton or dedimethamine intermediates were reported for the first time. The proposed degradation pathway of MB predominantly proceeded with the rupture of phenothiazine rings oxided with ?OH, HO?? and singlet oxygen (1O2) radicals, which fully extending the reaction pathways proposed in previous work in literature. The enhanced catalytic activity of β-FeOOH@GO was ascribed to the formation of heterojunctions confirmed by the presence of Fe-O-C chemical bonds through X-ray photoelectron spectroscopy (XPS). The complete elimination of MB and its acute toxicity to Luminous bacteria showed that β-FeOOH@GO would be served as a highly efficient Fenton-like catalyst for treatment of high concentration refractory organic contaminant.
关键词： Degradation mechanism,Graphene oxide,Methylene blue,β-FeOOH,Photo-Fenton-like reaction
更新于2025-09-10 09:29:36
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Antimicrobial efficacy of methylene blue-mediated photodynamic therapy on titanium alloy surfaces in vitro
摘要： Bacterial elimination using antimicrobial photodynamic therapy (aPDT) has been considered an alternative therapeutic modality in peri-implantitis treatment. The present in vitro study was to evaluate the dose-dependent and pH-dependent bactericidal effects of methylene blue (MB)-mediated aPDT on eliminating Gram-negative (P. gingivalis and A. actinomycetemcomitans) and Gram-positive (S. mutans) bacteria on sandblasting, large-grit and acid-etching (SLA)-pretreated titanium alloy. The effects of different MB concentrations (50, 100, and 200 μg/mL), the pH of the MB (4, 7, and 10), and irradiation time (0, 30, and 60 sec) on the bacterial viability and residual lipopolysaccharide (LPS) levels were examined. The variations in the pH of the MB solution after aPDT for 60 sec on the uncontaminated and contaminated specimens were also detected. The experimental results indicated that MB-mediated PDT could effectively kill the majority of bacteria on the titanium alloy surfaces of biofilm-contaminated implants compared with the MB alone. Of note, aPDT exhibited better antibacterial efficacy with increase in the MB concentration and irradiation time. While treated in an acidic solution on the biofilm-contaminated specimens, aPDT caused the pH to increase. By contrast, the initially high alkaline pH decreased to a value of about pH 8.5 after aPDT. Intriguingly, the neutral pH had minor changes, independent of the MB concentration and bacterial species. As expected, aPDT with higher MB concentration at higher pH environment significantly lowered the LPS concentration of A. actinomycetemcomitans and P. gingivalis. On the basis of the data, the aPDT with 200 μg/mL MB at pH 10 for 60 sec of irradiation time might be an effectively treatment to eliminate bacteria and LPS adherent to titanium surface, however, the use of the multispecies biofilm model and the evaluation of in vitro osteogenesis needed to be further evaluated.
关键词： Peri-implantitis,Antimicrobial activity,Lipopolysaccharide,Methylene blue,Photodynamic therapy
更新于2025-09-10 09:29:36
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MoS2/ZnO nanocomposites for efficient photocatalytic degradation of industrial pollutants
摘要： In the present work, molybdenum disulphide-zinc oxide (MoS2/ZnO) nanocomposites were synthesized via a simple dual step hydrothermal reduction method using hydrazine hydrate as a reducing agent. The as prepared nanocomposites have been characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman and photoluminescence (PL) spectroscopy. The structural and morphological analysis showed that particles are crystalline in nature and cubical in shape with an average size of ~22.5 nm.The nanocomposites were evaluated for photocatalytic property. The degradation analysis of industrial pollutants such as Novacron red Hunts- man (NRH) and methylene blue (MB) dye reveals that MoS2/ZnO nanocomposite is an efficient catalyst.
关键词： XPS,Novacron red Huntsman dye,Photocatalyst,Methylene blue,MoS2/ZnO
更新于2025-09-10 09:29:36
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Hydrogen Peroxide Enhances the Antibacterial Effect of Methylene Blue-based Photodynamic Therapy on Biofilm-forming Bacteria
摘要： Recently, increased attention has been focused on endoscopic disinfection after outbreaks of drug resistant infections associated with gastrointestinal endoscopy. The aims of this study were to investigate the bactericidal efficacy of methylene blue (MB)-based photodynamic therapy (PDT) on Pseudomonas aeruginosa (P. aeruginosa), which is the major cause of drug resistant post-endoscopy outbreak, and to assess the synergistic effects of hydrogen peroxide addition to MB-based PDT on biofilms. In planktonic state of P. aeruginosa, the maximum decrease was 3 log10 and 5.5 log10 at 20 and 30 J / cm2, respectively, following MB-based PDT. However, the maximum reduction of colony forming unit (CFU) was decreased by 2.5 log10 and 3 log10 irradiation on biofilms. The biofilm formation was significantly inhibited upon irradiation with MB-based PDT. When the biofilm state of P. aeruginosa was treated with MB-based PDT with hydrogen peroxide, the CFU was significantly decreased by 6 log10 after 20 J / cm2, by 7 log10 after 30 J / cm2 irradiation, suggesting significantly higher efficacy than MB-based PDT alone. The implementation of the combination of hydrogen peroxide with MB-based PDT through working channels might be appropriate for preventing early colonization and biofilm formation in the endoscope and post-endoscopy outbreak.
关键词： methylene blue,endoscopic disinfection,hydrogen peroxide,Pseudomonas aeruginosa,photodynamic therapy,biofilm
更新于2025-09-10 09:29:36