جستجوی مقالات مرتبط با کلیدواژه « s. aureus » در نشریات گروه « شیمی »

The gram-negative Escherichia coli (E-coli) and gram-positive Staphylococcus aureus (S-aureus) bacteria may lead to foodborne diseases if they are allowed to enter the bloodstream. The potential risk of bacteria colonization is expected for the consumers of many food products, such as milk, meat, etc. Hence, the separation of these types of bacteria from blood is pivotal for choosing effective treatments. The present study proposes a dielectrophoretic microfluidic device to isolateE-coli and S-aureus bacteria from blood cells using COMSOL Multiphysics 5.6 software. The results demonstrate that the applied potential and frequency, the distance between electrodes, and the buffer-to-sample inlet velocity ratio affect bacterial capture. The present work concludes that the isolation of bacteria from blood cells using the proposed microchip and studied parameters is practical when the blood behaves as a non-Newtonian fluid. Accordingly, the optimal conditions for the complete separation of E-coli and S-aureus bacteria from blood cells can be achieved for the electrode distance of 60 μm, the potential of 100 V, and the frequency of 0.1 MHz when the buffer-to-sample flow rate is 3.

The spread of incurable diseases, especially infectious diseases caused by antibiotic-resistant bacteria and certain cancers, has become a serious public health concern. Consequently, the search for potent drug scaffolds has played an essential role in drug lead discovery. The multicomponent reaction (MCR) offers a novel method for efficient synthesis. It is rapidly evolving and is important for the discovery of novel molecules. We synthesized four dihydropyrimidinone (DHPM) derivatives with the one-pot MCR method, obtaining compounds 1-4. According to the NMR spectra analyses, compound 3 is a new derivative. In this experiment, we optimized the pH of the process. Based on the results, 1-4 had yields of 66.6, 72.9, 35.9, and 69.0%, respectively, at a pH of 4. In contrast, all yields significantly rose by 79.4, 91.9, 81.7, and 84.0% at pH 5. A pH of 5 was therefore advantageous for getting a high yield from these reactions. Compound 1 showed a significant inhibition against E. coli with an MIC value of 12.5 µg/mL with moderate activity against the breast cancer cell lines T47D and 4T1. Compound 3 was the most potent against S. aureus, with an MIC value of 25 µg/mL.

Rapid augmentation in the prevalence of multidrug-resistant (MDR) Staphylococcus aureus is a worldwide threat. Advising newer antibiotics may fail to reduce the chances of the emergence of newer drug-resistant Staphylococcus aureus. Very little shreds of evidence can be found to treat clinical MDR Staphylococcus aureus with biogenic silver nanoparticles (AgNPs) in West Bengal. To prepare AgNPs biogenically using aqueous tulsi leaf extract (TLE) and also to assess its antibacterial effect upon clinical MDR Staphylococcus aureus, biogenic synthesis of the AgNPs using aqueous TLE was done, characterized those with UV-Vis Spectrophotometer, dynamic light scattering, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and evaluated the antibacterial activity against the clinical MDR Staphylococcus aureus. ANOVA followed by LSD post hoc test was used to test the differences between the OD (optical density) of different experimental sets. The biosynthesized AgNPs were spherical, monodispersed, and of smaller size (9-23 nm) with the involvement of eugenol, quercetin, and oleanolic acid present in the tulsi leaf. A significant change in OD was observed in AgNPs (prepared using TLE) treated broth compared to only tulsi leaf extract treated culture. There was a significant similarity between the efficacies of AgNPs and clindamycin (P < 0.05). Our findings propose that AgNPs synthesized using TLE were fast and efficient to ameliorate the bacterial growth, which may be used as a potent antibacterial agent for the treatment of clinical MDR Staphylococcus aureus infection in near future.

Preservative capacity is measured for seventeen currently accessible Iranian made shampoo products. Upon purchase, bacterial counts show no trace of any microbial contamination. The shampoo bottles are distributed to seventeen female graduate students, residing at the time in different dormitories of Tarbiat Modares University (TMU). After 40 days, the allocated bottles are returned and their bacterial counts repeated, under the same conditions. To our surprise, no trace of any microbial contamination is observed. Three possibilities are considered. 1) The factory employed preservative(s) act very efficiently. 2) The shampoo component(s) are themselves bactericidal. 3) Existence of sanitary conditions and the absence of any microbial contaminants at TMU! Evidently, the third possibility is ruled out. The second choice is also discarded, because practically no significant antimicrobial activity is demonstrated by any of the four main ingredients of the shampoos including sodium lauryl ether sulfate (SLES), betaine, coconut fatty acid, and glycerin. Hence, the most likely possibility is the first one, since upon deliberate contamination of the seventeen brands; the factory employed preservatives [5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (KATHON CG)] prove highly bactericidal against four major contaminants: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and the methicillin-resistant Staphylococcus aureus (MRSA).

The review article summarizes the applications of silver nanoparticles for diverse sectors. Over the decades, nanoparticles used as dignified metals such as silver exhibited distinctive characteristics basically correlated to chemical, physical and biological property of counterparts having bulkiness. Numerous studies reported that Nanoparticles of about 100nm diameter play a crucial role in widely spread industries due to unique properties including the dimension of small particle, high surface area and quantum confinement and they dispersed without agglomeration. Decade of discoveries clearly established that shape, size and distribution of Silver nanoparticles strongly affect the electromagnetic, optical and catalytic properties, which are often an assortment of changeable synthetic methods and reducing agents with stabilizers. Generation after generation the postulates come forth about properties of silver for the ancient Greeks cook from silver pots and the old adage ‘born with a silver spoon in his mouth’ thus show that eating with a silver spoon was well-known as uncontaminated. Impregnation of metals with silver nanoparticles is a practical way to exploit the microbe aggressive properties of silver at very low cost. The nanoparticles help in targeted delivery of drugs, enhancing bioavailability, sustaining drug or gene effect in target tissues, and enhancing the stability. Implementations of silver partials in medical science and biological science have been noticed from years ago; however alteration with nanotechnology is innovative potential. Over 23% of all nanotechnology based products, diagnostic and therapeutic applications implanted with silver nanoparticles (e.g. In arthritic disease and wound healing, etc.) and widely known for their antifungal, antibacterial, antiviral effect, employed in textile fabrics and added into cosmetic products as antiseptic to overcome skin problems. Thus, Silver nanoparticles (AgNPs) have been urbanized as an advanced artifact in the field of nanotechnology.

Following our interest in reaching for a molded rubber article with possible detergent contact applications, durable silver nanopowder (AgNP) is synthesized by arc discharge, then mixed with varying ratios of ethylene propylene rubber (EPR), affording novel AgNP@EPR nanocomposites. X-ray diffraction (XRD) patterns of AgNP as well as AgNP@EPR show no trace of impurity, while scanning electron microscopy (SEM) indicates an average diameter of 50 nm for the former. Transmission electron microscopy (TEM) images while confirm the SEM results, show quite a few 5 nm AgNP particles lying beside some micro crumbs. Our DC arc discharge technique involves explosion of movable silver anode and static cathode by a current pulse between 5 to 10 A cm-2. A solution blending method is employed for preparation of AgNP@EPR nanocomposites. The AgNP is first dispersed in toluene using an ultrasonic homogenizer, and then thoroughly mixed with EPR in the same solvent whose removal gives nanocomposites of 2, 4, 6 and 8 vol% AgNP in EPR,  showing strong antibacterial activity against both Escherichia coli and Staphylococcus aureus.

In this study, Zinc Oxide nanoparticles (ZnONPs) were synthesized by chemical method and their antibacterial efficiency against a clinical isolate of Staphylococcus aureus was studied. The Zinc Oxide nanoparticles have shown a commendable inhibition effect on the growth of most notorious bacterial pathogen S.aureus. The nanoparticles size and shapes were characterized by transmission electron microscopy (TEM). The rod shaped zinc nanoparticles were formed as as a result of fast reduction rate of the precursor. The shape controlled nanocrystals possess well defined surfaces and morphologies and showed an excellent antibacterial property against clinical bacterial strain S. aureus.