Methylene Blue
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2021 ◽  
Vol 3 (10) ◽  
Alistair Hampden-Martin ◽  
Jo Fothergill ◽  
Mohamed El Mohtadi ◽  
Lucy Chambers ◽  
Anthony J. Slate ◽  

Photodynamic antimicrobial chemotherapy (PACT) is a novel alternative antimicrobial therapy that elicits a broad mechanism of action and therefore has a low probability of generating resistance. Such properties make PACT ideally suited for utilization in localized applications such as burn wounds. The aim of this study was to determine the antimicrobial activity of MB and temoporfin against both a S. aureus isolate and a P. aeruginosa isolate in light (640 nm) and dark conditions at a range of time points (0–20 min). A Staphylococcus aureus isolate and a Pseudomonas aeruginosa isolate were treated in vitro with methylene blue (MB) and temoporfin under different conditions following exposure to light at 640 nm and in no-light (dark) conditions. Bacterial cell viability [colony-forming units (c.f.u.) ml−1] was then calculated. Against P. aeruginosa , when MB was used as the photosensitizer, no phototoxic effect was observed in either light or dark conditions. After treatment with temoporfin, a reduction of less than one log (7.00×107 c.f.u. ml−1) was observed in the light after 20 min of exposure. However, temoporfin completely eradicated S. aureus in both light and dark conditions after 1 min (where a seven log reduction in c.f.u. ml−1 was observed). Methylene blue resulted in a loss of S. aureus viability, with a two log reduction in bacterial viability (c.f.u. ml−1) reported in both light and dark conditions after 20 min exposure time. Temoporfin demonstrated greater antimicrobial efficacy than MB against both the S. aureus and P. aeruginosa isolates tested. At 12.5 µM temoporfin resulted in complete eradication of S. aureus . In light of this study, further research into the validity of PACT, coupled with the photosensitizers (such as temoporfin), should be conducted in order to potentially develop alternative antimicrobial treatment regimes for burn wounds.

Heri Sutanto ◽  
Ilham Alkian ◽  
Mukholit Mukholit ◽  
Arsyadio Aditya Nugraha ◽  
Eko Hidayanto ◽  

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Ge Yan ◽  
Pu Wang ◽  
Yuqian Li ◽  
Zhangjie Qin ◽  
Shuai Lan ◽  

The material, δ-MnO2, has exhibited superior performance on the removal of methylene blue (MB), but the process is significantly impacted by pH, and the impacting mechanism is still unclear. In this study, the effects of pH on the removal mechanism of MB using synthesized δ-MnO2 were investigated by distinguishing the adsorption and oxidation of MB by δ-MnO2 during the removal process in the dark. The results show that the total removal efficiency of MB by δ-MnO2 decreased significantly with an increase in the pH. MB could be removed by δ-MnO2 via an adsorption mechanism and oxidation mechanism, and the proportion of adsorptive removal and oxidative removal was different under different pH conditions. With an increase in the initial pH from 2.00 to 8.05, the redox potential of δ-MnO2 decreased, and its oxidation ability for the removal of MB also gradually decreased. In contrast, the surface negative charges of δ-MnO2 increased with an increase in the pH, and the adsorption ability towards positively charged MB also gradually increased. This indicates that the effects of pH on the removal of MB by δ-MnO2 are primarily dominated by its influence on the oxidation ability of δ-MnO2. In addition, it is further proved that the pH value has a significant effect on the oxidation and adsorption of MB on δ-MnO2. Moreover, the significant effects of pH on the oxidation of MB by δ-MnO2 are further demonstrated by observing the changes in Mn2+ and the UV-Vis spectra of intermediate products during the reaction, as well as the changes in the FTIR and XPS characterizations of δ-MnO2 after the reaction.

R. Ismail ◽  
H. Awad ◽  
R. Allam ◽  
O. Youssef ◽  
M. Ibrahim ◽  

BACKGROUND: Refractory septic shock in neonates is still associated with high mortality, necessitating an alternative therapy, despite all currently available treatments. This study aims to assess the vasopressor effect of methylene blue (MB) in comparison to terlipressin (TP) as adjuvant therapy for refractory septic shock in the preterm neonate. METHODS: A double-blinded randomized controlled trial was conducted in the Neonatal Intensive Care Units at Ain Shams University, Egypt. Thirty preterm neonates with refractory septic shock were randomized to receive either MB or TP as an adjuvant to conventional therapy. Both MB and TP were administered as an intravenous loading dose followed by continuous intravenous infusion. The hemodynamic variables, functional echocardiographic variables, and oxidant stress marker were assessed over a 24 h period together with the side effects of MB. RESULTS: MB causes significant improvement in mean arterial blood pressure with a significant decrease of the norepinephrine requirements (1.15±0.21μm/kg/min at baseline vs. 0.55±0.15μm/kg/min at 24 h). MB infusion causes an increase of the pulmonary pressure (44.73±8.53 mmHg at baseline vs. 47.27±7.91 mmHg after 24 h) without affecting the cardiac output. Serum malonaldehyde decreased from 5.45±1.30 nmol/mL at baseline to 4.40±0.90 nmol/mL at 24 h in the MB group. CONCLUSION: Administration of MB to preterm infants with refractory septic shock showed rapid increases in systemic vascular resistance and arterial blood pressure with minimal side effects.

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3659
Nouf Faisal Alharby ◽  
Ruwayda S. Almutairi ◽  
Nadia A. Mohamed

The chemical cross-linking of carboxymethyl chitosan (O-CM-chitosan), as a method for its modification, was performed using trimellitic anhydride isothiocyanate to obtain novel cross-linked O-CM-chitosan hydrogel. Its structure was proven using FTIR, XRD and SEM. Its adsorption capacity for the removal of Methylene Blue (MB) dye from aqueous solution was studied. The effects of different factors on the adsorption process, such as the pH, temperature and concentration of the dye, in addition to applications of the kinetic studies of the adsorption process, adsorption isotherm and thermodynamic parameters, were studied. It was found that the amount of adsorbed MB dye increases with increasing temperature. A significant increase was obtained in the adsorption capacities and removal percentage of MB dye with increasing pH values. An increase in the initial dye concentration increases the adsorption capacities, and decreases the removal percentage. It was found that the pseudo-second-order mechanism is predominant, and the overall rate of the dye adsorption process appears to be controlled by more than one step. The Langmuir model showed high applicability for the adsorption of MB dye onto O-CM-chitosan hydrogel. The value of the activation energy (Ea) is 27.15 kJ mol−1 and the thermodynamic parameters were evaluated. The regeneration and reuse of the investigated adsorbent was investigated.

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6343
Burcu Gunes ◽  
Yannick Jaquet ◽  
Laura Sánchez ◽  
Rebecca Pumarino ◽  
Declan McGlade ◽  

The remarkable adsorption capacity of graphene-derived materials has prompted their examination in composite materials suitable for deployment in treatment of contaminated waters. In this study, crosslinked calcium alginate–graphene oxide beads were prepared and activated by exposure to pH 4 by using 0.1M HCl. The activated beads were investigated as novel adsorbents for the removal of organic pollutants (methylene blue dye and the pharmaceuticals famotidine and diclofenac) with a range of physicochemical properties. The effects of initial pollutant concentration, temperature, pH, and adsorbent dose were investigated, and kinetic models were examined for fit to the data. The maximum adsorption capacities qmax obtained were 1334, 35.50 and 36.35 mg g−1 for the uptake of methylene blue, famotidine and diclofenac, respectively. The equilibrium adsorption had an alignment with Langmuir isotherms, while the kinetics were most accurately modelled using pseudo- first-order and second order models according to the regression analysis. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated and the adsorption process was determined to be exothermic and spontaneous.

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2801
Guang Feng ◽  
Mengyun Hu ◽  
Shuai Yuan ◽  
Junyi Nan ◽  
Heping Zeng

Hydrogenated crystalline TiO2 with oxygen vacancy (OV) defect has been broadly investigated in recent years. Different from crystalline TiO2, hydrogenated amorphous TiO2−x for advanced photocatalytic applications is scarcely reported. In this work, we prepared hydrogenated amorphous TiO2−x (HA-TiO2−x) using a unique liquid plasma hydrogenation strategy, and demonstrated its highly visible-light photoactivity. Density functional theory combined with comprehensive analyses was to gain fundamental understanding of the correlation among the OV concentration, electronic band structure, photon capturing, reactive oxygen species (ROS) generation, and photocatalytic activity. One important finding was that the narrower the bandgap HA-TiO2−x possessed, the higher photocatalytic efficiency it exhibited. Given the narrow bandgap and extraordinary visible-light absorption, HA-TiO2−x showed excellent visible-light photodegradation in rhodamine B (98.7%), methylene blue (99.85%), and theophylline (99.87) within two hours, as well as long-term stability. The total organic carbon (TOC) removal rates of rhodamine B, methylene blue, and theophylline were measured to 55%, 61.8%, and 50.7%, respectively, which indicated that HA-TiO2−x exhibited high wastewater purification performance. This study provided a direct and effective hydrogenation method to produce reduced amorphous TiO2−x which has great potential in practical environmental remediation.

Iliane Muller Otto ◽  
Luiza Beatriz Gamboa Araújo Morselli ◽  
Dienifer Aline Braun Bunde ◽  
Simone Pieniz ◽  
Maurízio Silveira Quadro ◽  

The textile industry, very important for the world economy, generates an effluent containing dyes, and which, when discarded in water bodies without proper treatment, can cause impacts to human health and the environment. One of these widely used dyes is methylene blue, whose characteristics are high solubility in water and its toxic potential, and which effects range from eye irritations, nausea, vomiting and even mental confusion. Among the potential adsorbents of this dye is chitin, which is a biopolymer extracted from the shrimp exoskeleton. Aiming at the development of a low-cost adsorbent material with potential use in the textile effluent treatment industry, the ability to remove methylene blue dye by shrimp residue chitin, obtained by eleven different methodologies, was verified. The three most efficient treatments reached approximately 75% of dye removal, proving the high adsorption power of shrimp residue. In addition to providing technological development of materials, the research brings socioeconomic benefits to the fishermen’s colony with the use of shrimp residue for the adsorption of other waste from the textile industry, contributing to the sustainability of both activities and reducing the environmental impact.

Polymer ◽  
2021 ◽  
Vol 235 ◽  
pp. 124257
Camilla Noè ◽  
Andrea Cosola ◽  
Annalisa Chiappone ◽  
Minna Hakkarainen ◽  
Hansjörg Grützmacher ◽  

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