Search Results (7)

Background: Bacterial resistance to antimicrobial drugs is a critical phenomenon that is hampering clinical treatments, raising the need for promising compounds that can be explored as pharmaceutical products. This study investigated the antimicrobial potential of α-Ag₂WO₄–alpha phase, orthorhombic structure silver tungstate nanoparticles (STN), against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, alone and combined to clinically relevant antimicrobial drugs. Methods: We used classical methods (MIC/checkerboard) to investigate the antimicrobial activity of STN. We characterized STN using X-ray diffraction, photoluminescence and scanning electron microscopy. We also performed cytotoxicity tests on BGM cells and anti-inflammatory tests in vitro. Results: STN was effective at 128 µg/mL for S. aureus and at 256 µg/mL for E. coli, but was not effective against P. aeruginosa. When combined with antimicrobials, STN decreased their MIC values, and its anti-inflammatory potential was confirmed. CC₅₀ of STN was of 16.23 ± 1.09 μg/mL against BGM cells. Conclusions: Our data open doors for further studies in animal models to investigate the effects on STN in infectious diseases. Full article

Due to the rapid increase in the use of anti-aging cosmetic products, there is a need to develop valid analytical methods to control their quality. The present work deals with the development and validation of a new chromatographic method for the quantitative determination of five lipophilic components (resveratrol, ferulic acid, quercetin, retinol, and α-tocopherol), with anti-aging properties, in a cold cream (w/o). For the HPLC-UV separation of the active ingredients, an HS, Discovery^® Supelco (Supelco Inc., Bellefonte, PA, USA), C₁₈ column (25 cm × 4.6 mm), 5 μm (at 40 °C) was used as a stationary phase while a binary system of A: Acetonitrile with formic acid 0.2% and B: H₂O with formic acid 0.2%, in gradient elution (flow 1.5 mL·min⁻¹), was used as mobile. The analytical method was validated according to ICH guidelines Q2(R2), where linearity (r² ≥ 0.998), selectivity, precision (% recovery 97.1–101.9), and accuracy (%RSD < 2) were evaluated. The processing of the samples for the recovery of the five analytes from the cream was investigated by experimental design methodology and the cross D-optimal technique (% recovery 98.5–102.9, %RSD < 2%, n = 5). Finally, the same analysis was applied to study the transdermal penetration of the active ingredients incorporated in cold cream (over a period of 8 h). Their behavior was compared with the corresponding one in suspension using Franz cells in a vertical arrangement. The new method is considered reliable for the analysis of the anti-aging product. Full article

In this work, α-Ag₂WO₄ particles with different cross-sections were obtained using the co-precipitation method at different synthesis temperatures. The samples were characterized by X-ray diffraction (XRD), field-scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The antimicrobial activity was analyzed using the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) methods against the Escherichia coli and Salmonella spp. gram-negative bacteria. The antimicrobial tests against Escherichia coli and Salmonella spp. indicated that concentrations of 2.5–5 mg/mL and 5 mg/mL completely inhibit its growth, respectively. The antimicrobial activity was analyzed employing band-edge positions for ROS generations and the superficial distribution of Ag⁺ species that contribute to antimicrobial activity. Quantum-chemical calculations were used at the DFT level to investigate the surface-dependent reactivity of α-Ag₂WO₄, and we demonstrated how the antimicrobial properties could be tailored by the geometry and electronic structure of the exposed surfaces, providing guidelines for the morphology design. Full article

Size and morphology control during the synthesis of materials requires a molecular-level understanding of how the addition of surface ligands regulates nucleation and growth. In this work, this control is achieved by using three carboxylic acids (tartaric, benzoic, and citric) during sonochemical syntheses. The presence of carboxylic acids affects the kinetics of the nucleation process, alters the growth rate, and governs the size and morphology. Samples synthesized with citric acid revealed excellent photocatalytic activity for the degradation process of Rhodamine B, and recyclability experiments demonstrate that it retains 91% of its photocatalytic activity after four recycles. Scavenger experiments indicate that both the hydroxyl radical and the hole are key species for the success of the transformation. A reaction pathway is proposed that involves a series of dissolution−hydration–dehydration and precipitation processes, mediated by the complexation of Ag⁺. We believe these studies contribute to a fundamental understanding of the crystallization process and provide guidance as to how carboxylic acids can influence the synthesis of materials with controlled size and morphology, which is promising for multiple other scientific fields, such as sensor and catalysis fields. Full article

In this work, α-Ag_2−2xCu_xWO₄ (0 ≤ x ≤ 0.16) solid solutions with enhanced antibacterial (against methicillin-resistant Staphylococcus aureus) and antifungal (against Candida albicans) activities are reported. A plethora of techniques (X-ray diffraction with Rietveld refinements, inductively coupled plasma atomic emission spectrometry, micro-Raman spectroscopy, attenuated total reflectance–Fourier transform infrared spectroscopy, field emission scanning electron microscopy, ultraviolet–visible spectroscopy, photoluminescence emissions, and X-ray photoelectron spectroscopy) were employed to characterize the as-synthetized samples and determine the local coordination geometry of Cu²⁺ cations at the orthorhombic lattice. To find a correlation between morphology and biocide activity, the experimental results were sustained by first-principles calculations at the density functional theory level to decipher the cluster coordinations and electronic properties of the exposed surfaces. Based on the analysis of the under-coordinated Ag and Cu clusters at the (010) and (101) exposed surfaces, we propose a mechanism to explain the biocide activity of these solid solutions. Full article

Physical activity, particularly high-intensity eccentric muscle contractions, produces exercise-induced muscle damage (EIMD). The breakdown of muscle fibers and the consequent inflammatory responses derived from EIMD affect exercise performance. Curcumin, a natural polyphenol extracted from turmeric, has been shown to have mainly antioxidant and also anti-inflammatory properties. This effect of curcumin could improve EIMD and exercise performance. The main objective of this systematic review was to critically evaluate the effectiveness of curcumin supplementation on EIMD and inflammatory and oxidative markers in a physically active population. A structured search was carried out following Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in the databases SCOPUS, Web of Science (WOS), and Medline (PubMed) from inception to October 2019. The search included original articles with randomized controlled crossover or parallel design in which the intake of curcumin administered before and/or after exercise was compared with an identical placebo situation. No filters were applied to the type of physical exercise performed, the sex or the age of the participants. Of the 301 articles identified in the search, 11 met the established criteria and were included in this systematic review. The methodological quality of the studies was assessed using the McMaster Critical Review Form. The use of curcumin reduces the subjective perception of the intensity of muscle pain; reduces muscle damage through the decrease of creatine kinase (CK); increases muscle performance; has an anti-inflammatory effect by modulating the pro-inflammatory cytokines, such as TNF-α, IL-6, and IL-8; and may have a slight antioxidant effect. In summary, the administration of curcumin at a dose between 150–1500 mg/day before and during exercise, and up until 72 h’ post-exercise, improved performance by reducing EIMD and modulating the inflammation caused by physical activity. In addition, humans appear to be able to tolerate high doses of curcumin without significant side-effects. Full article

Selective catalytic reduction (SCR) is one of the most effective technologies used for eliminating NO_x from diesel engines. This paper presents a novel method based on a support vector machine (SVM) and particle swarm optimization (PSO) with grid search (GS) to diagnose the degree of aging of the V₂O₅/WO₃–TiO₂ catalyst in the SCR system. This study shows the aging effect on the performance of a NH₃ slip based closed-loop SCR control system under different aging factors (α), which are defined by the SCR reaction rate ( $R_{\mathrm{scr}}$ ). A diagnosis of the performance of GS–PSO–SVM has been presented as compared to SVM, GS–SVM and PSO–SVM to get reliable results. The results show that the average prediction diagnosis accuracy of the degree of catalytic aging is up to 93.8%, 93.1%, 92.9% and 92.0% for GS–PSO–SVM, PSO–SVM, GS–SVM and SVM respectively. It is demonstrated that GS–PSO–SVM is able to identify the SCR catalyst’s degree of aging, to ultimately assist with fault tolerance in the aging of the SCR catalyst. Full article