Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis of metallic silver nanoparticles. Stable silver nanoparticles were formed by treating aqueous solution of AgNO(3) with the plant leaf extracts as reducing agent of Ag(+) to Ag(0). UV-visible spectroscopy was used to monitor the quantitative formation of silver nanoparticles. Magnolia leaf broth was the best reducing agent in terms of synthesis rate and conversion to silver nanoparticles. Only 11 min was required for more than 90% conversion at the reaction temperature of 95 degrees C using Magnolia leaf broth. The synthesized silver nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle analyzer. The average particle size ranged from 15 to 500 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO(3) concentration. This environmentally friendly method of biological silver nanoparticles production provides rates of synthesis faster or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods and medical applications.

Background: The novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is responsible for the global coronavirus disease 2019 pandemic. Small studies have shown a potential benefit of chloroquine/hydroxychloroquine±azithromycin for the treatment of coronavirus disease 2019. Use of these medications alone, or in combination, can lead to a prolongation of the QT interval, possibly increasing the risk of Torsade de pointes and sudden cardiac death. Methods: Hospitalized patients treated with chloroquine/hydroxychloroquine±azithromycin from March 1 to the 23 at 3 hospitals within the Northwell Health system were included in this prospective, observational study. Serial assessments of the QT interval were performed. The primary outcome was QT prolongation resulting in Torsade de pointes. Secondary outcomes included QT prolongation, the need to prematurely discontinue any of the medications due to QT prolongation, and arrhythmogenic death. Results: Two hundred one patients were treated for coronavirus disease 2019 with chloroquine/hydroxychloroquine. Ten patients (5.0%) received chloroquine, 191 (95.0%) received hydroxychloroquine, and 119 (59.2%) also received azithromycin. The primary outcome of torsade de pointes was not observed in the entire population. Baseline corrected QT interval intervals did not differ between patients treated with chloroquine/hydroxychloroquine (monotherapy group) versus those treated with combination group (chloroquine/hydroxychloroquine and azithromycin; 440.6±24.9 versus 439.9±24.7 ms, P =0.834). The maximum corrected QT interval during treatment was significantly longer in the combination group versus the monotherapy group (470.4±45.0 ms versus 453.3±37.0 ms, P =0.004). Seven patients (3.5%) required discontinuation of these medications due to corrected QT interval prolongation. No arrhythmogenic deaths were reported. Conclusions: In the largest reported cohort of coronavirus disease 2019 patients to date treated with chloroquine/hydroxychloroquine±azithromycin, no instances of Torsade de pointes, or arrhythmogenic death were reported. Although use of these medications resulted in QT prolongation, clinicians seldomly needed to discontinue therapy. Further study of the need for QT interval monitoring is needed before final recommendations can be made.

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The leaf extract of Diopyros kaki was used as a reducing agent in the ecofriendly extracellular synthesis of platinum nanoparticles from an aqueous H(2)PtCl(6).6H(2)O solution. A greater than 90% conversion of platinum ions to nanoparticles was achieved with a reaction temperature of 95 degrees C and a leaf broth concentration of >10%. A variety of methods was used to characterize the platinum nanoparticles synthesized: inductively coupled plasma spectrometry, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The average particle size ranged from 2 to 12 nm depending on the reaction temperature and concentrations of the leaf broth and PtCl(6) (2-). FTIR analysis suggests that platinum nanoparticle synthesis using Diopyros kaki is not an enzyme-mediated process. This is the first report of platinum nanoparticle synthesis using a plant extract.

The presence of microorganisms, such as Escherichia coli, Salmonella, Listeria, and Vibrio, in food can be a serious threat to health, especially for infants, the elderly, and immunodeficient patients. The most reliable and accurate method for detecting food-borne pathogens is the conventional culture method, which includes a culture process and phenotypic or metabolic fingerprinting. [1] However, this method has the drawbacks that it is labor-intensive and requires at least 1-2 days to identify the pathogen(s). Therefore, researchers are looking for new methods that are fast, inexpensive, lightweight, and highly sensitive. Nanotechnology combined with biotechnology could potentially form the basis for such a method, and there have been efforts to develop fast and ultrasensitive nanosensors that can detect pathogens. To date, various platforms for pathogen detection have been developed, including metallic striped nanowires, [2] fluorescent nanobarcodes, [3] nanoparticles, [4,5] nanoelectromechanical systems (NEMs), [6] and microfluidic modules. [7,8] Herein, we demonstrate a screening tool for microorganisms such as E. coli, based on aptamer-functionalized single-walled carbon-nanotube field-effect transistor (SWNT-FET) arrays combined with the most probable number (MPN) method. Nanoscale biosensors based on FETs have been shown to be sufficiently sensitive to detect single viruses, [9] tumor-specific antigens, [10,11] and small molecules. [12] Moreover, in a previous study we showed that aptamer-functionalized SWNT-FET sensors can be used as sensitive, recyclable biosensors. [13] Nanosensors require only very small sample volumes (on the order of microliters), a characteristic that is advantageous in many instances but which can be a problem for inhomogeneous samples. Specifically, the probability that a collection of microorganisms in water will be distributed perfectly uniformly throughout the solution is very low. For example, if a 1-mL solution contains 10 3 E. coli cells, it does not necessarily mean that every 1-mL aliquot of the solution contains a single cell; rather, some aliquots will contain more than one cell, and others will not contain any cells. Thus, although each aliquot contains a single E. coli cell on average, there is a high possibility of recording a false signal if only a small volume of the solution is sampled. Microfluidic channels combined with nanosensors can solve this problem to some extent, but the volumes used are too small to avoid statistical errors. Moreover, motile bacteria such as E. coli can move at % 20 mm s À1 in a favorable medium, [14] which increases the difficulty of detecting these microorganisms using sensors with nanometer-sized sensing areas.Microbiologists have solved this problem by using a simple method called MPN. [15] First developed in 1933, MPN is still considered to be an important technique in estimating microbial populations in soils, waters, the food industry, etc. In MPN, to determine the cell titer in a particular solution, that solution is diluted at l...

Alcaligenes eutrophus NCIMB 11599 was cultivated to produce poly(3-hydroxybutyric acid) (PHB) from glucose by the automatic fed-batch culture technique. The glucose concentration of the culture broth was controlled at 10 to 20 g/L by two methods: using exit gas data obtained from a mass spectrometer and using an on-line glucose analyzer. The effect of ammonium limitation on PHB synthesis at different culture phases was studied. The final cell concentration, PHB concentration, and PHB productivity increased as ammonia feeding was stopped at a higher cell concentration. High concentrations of PHB (121 g/L) and total cells (164 g/L) were obtained in 50 h when ammonia feeding was stopped at the cell concentration of 70 g/L. The maximum PHB content reached 76% of dry cell weight and the productivity was 2.42 g/L h with the yield of 0.3 g PHB/g glucose.

Objective. As are the attenuation coefficient and sound speed, the backscatter coefficient is a fundamental ultrasonic property that has been used to characterize many tissues. Unfortunately, there is currently far less standardization for the ultrasonic backscatter measurement than for the other two, as evidenced by a previous American Institute of Ultrasound in Medicine (AIUM)-sponsored interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements (J Ultrasound Med 1999; 18:615-631). To explore reasons for these disparities, the AIUM Endowment for Education and Research recently supported this second interlaboratory comparison, which extends the upper limit of the frequency range from 7 to 9 MHz. Methods. Eleven laboratories were provided with standard test objects designed and manufactured at the University of Wisconsin (Madison, WI). Each laboratory was asked to perform ultrasonic measurements of sound speed, attenuation coefficients, and backscatter coefficients. Each laboratory was blinded to the values of the ultrasonic properties of the test objects at the time the measurements were performed. Results. Eight of the 11 laboratories submitted results. The range of variation of absolute magnitude of backscatter coefficient measurements was about 2 orders of magnitude. If the results of 1 outlier laboratory are excluded, then the range is reduced to about 1 order of magnitude. Agreement regarding frequency dependence of backscatter was better than reported in the previous interlaboratory comparison. For example, when scatterers were small compared with the ultrasonic wavelength, experimental frequency-dependent backscatter coefficient data obtained by the participating laboratories were usually consistent with the expected Rayleigh scattering behavior (proportional to frequency to the fourth power). Conclusions. Greater standardization of backscatter measurement methods is needed. Measurements of frequency dependence of backscatter are more consistent than measurements of absolute magnitude.

Bakground Biological methods for metal nanoparticle synthesis using plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical methods. In the present study, copper nanoparticles were biologically synthesized using Magnolia kobus leaf extract as reducing agent and their antibacterial activity was evaluated against Escherichia coli. Results On treatment of aqueous solution of CuSO4·5H2O with Magnolia kobus leaf extract, stable copper nanoparticles were formed. UV–vis spectroscopy was used to monitor the quantitative formation of copper nanoparticles. The synthesized nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X‐ray spectroscopy (EDS), X‐ray photoelectron spectroscopy (XPS), and high‐resolution transmission electron microscopy (HR‐TEM). Electron microscopy analysis of copper nanoparticles indicated that they ranged in average size from 37 to 110 nm. Antibacterial tests were carried out by counting viable E. coli cells after 24 h growth in shake flasks containing latex foams coated with copper nanoparticles. As a result, foams coated with biologically synthesized copper nanoparticles showed higher antibacterial activity compared with foams untreated and foams treated with chemically synthesized copper nanoparticles using sodium borohydride and Tween 20. The antibacterial activities were inversely proportional to the average nanoparticle sizes. Conclusion The present results show that stable copper nanoparticles can be ecofriendly synthesized using Magnolia kobus leaf extract, offering an inexpensive alternative to antibacterial silver nanoparticles. © 2013 Society of Chemical Industry