scholarly journals Biosynthesis of Smaller-Sized Platinum Nanoparticles Using the Leaf Extract of Combretum erythrophyllum and Its Antibacterial Activities

Antibiotics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1275
Author(s):  
Olufunto T. Fanoro ◽  
Sundararajan Parani ◽  
Rodney Maluleke ◽  
Thabang C. Lebepe ◽  
Rajendran J. Varghese ◽  
...  
Keyword(s):  
Platinum Nanoparticles ◽  
Klebsiella Oxytoca ◽  
Particle Diameter ◽  
Cost Effective ◽  
Antibacterial Activities ◽  
Average Particle ◽  
Klebsiella Species ◽  
Green Materials ◽  
Transmission Electron ◽  
Materials Used

Nanobiotechnology is a promising field in the development of safe antibiotics to combat the increasing trend of antibiotic resistance. Nature is a vast reservoir for green materials used in the synthesis of non-toxic and environmentally friendly nano-antibiotics. We present for the first time a facile, green, cost-effective, plant-mediated synthesis of platinum nanoparticles (PtNPs) using the extract of Combretum erythrophyllum (CE) plant leaves. The extract of CE served as both a bio-reductant and a stabilizing agent. The as-synthesized PtNPs were characterized using ultraviolet-visible (UV–Vis) absorption spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and dynamic light scattering (DLS) techniques. The HR-TEM image confirmed that the PtNPs are ultrasmall, spherical, and well dispersed with an average particle diameter of 1.04 ± 0.26 nm. The PtNPs showed strong antibacterial activities against pathogenic Gram-positive Staphylococcus epidermidis (ATCC 14990) at a minimum inhibitory concentration (MIC) of 3.125 µg/mL and Gram-negative Klebsiella oxytoca (ATCC 8724) and Klebsiella aerogenes (ATCC 27853) at an MIC value of 1.56 µg/mL. The CE-stabilized PtNPs was mostly effective in Klebsiella species that are causative organisms in nosocomial infections.

scholarly journals Facile Green, Room-Temperature Synthesis of Gold Nanoparticles Using Combretum erythrophyllum Leaf Extract: Antibacterial and Cell Viability Studies against Normal and Cancerous Cells

Antibiotics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 893
Author(s):  
Olufunto T. Fanoro ◽  
Sundararajan Parani ◽  
Rodney Maluleke ◽  
Thabang C. Lebepe ◽  
Jose R. Varghese ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Cell Viability ◽  
Leaf Extract ◽  
Room Temperature ◽  
Klebsiella Oxytoca ◽  
Cost Effective ◽  
Average Diameter ◽  
Antibacterial Activities ◽  
Inhibition Concentration ◽  
First Time

We herein report a facile, green, cost-effective, plant-mediated synthesis of gold nanoparticles (AuNPs) for the first time using Combretum erythrophyllum (CE) plant leaves. The synthesis was conducted at room temperature using CE leaf extract serving as a reducing and capping agent. The as-synthesized AuNPs were found to be crystalline, well dispersed, and spherical in shape with an average diameter of 13.20 nm and an excellent stability of over 60 days. The AuNPs showed broad-spectrum antibacterial activities against both pathogenic Gram-positive (Staphylococcus epidermidis (ATCC14990), Staphylococcus aureus (ATCC 25923), Mycobacterium smegmatis (MC 215)) and Gram-negative bacteria (Proteus mirabilis (ATCC 7002), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13822), Klebsiella oxytoca (ATCC 8724)), with a minimum inhibition concentration of 62.5 µg/mL. In addition, the as-synthesized AuNPs were highly stable with exceptional cell viability towards normal cells (BHK- 21) and cancerous cancer cell lines (cervical and lung cancer).

Consolidation Features of Aluminum-Alumina Compositions by Powder Metallurgy Methods

2016 ◽  
Vol 254 ◽  
pp. 110-115
Author(s):  
Mihai Ovidiu Cojocaru ◽  
Mihaela Raluca Condruz ◽  
Florică Tudose
Keyword(s):  
Solid Phase ◽  
Particle Diameter ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Average Particle ◽  
Matrix Composites ◽  
Aluminum Particles ◽  
Transmission Electron ◽  
Tapped Density ◽  
Powder Metallurgy Methods

In this paper was followed the processing flow of aluminum-alumina compositions (10÷20% alumina) in powder state, aiming to obtain aluminum matrix composites reinforced with alumina particles, starting from selecting and mixing the grading fraction of both components reaching up to sintering; it was analyzed the way in which reflects the variation of grading fraction ratio (expressed through average particle diameter in the analyzed fractions limits) on the level of technological interest features: apparent density, tapped density, flowability, presability and on densification after sintering (in various environments). By transmission electron microscopy was observed that aluminum particles showed on the surface a nanoscale oxide film, so the sintering occurs between congeneric areas – by solid phase sintering mechanisms [1, 2, 3]. The analysis of thermophysical properties revealed a decrease of thermal diffusivity at an increase of alumina, simultaneous with the decrease of the densification level.

scholarly journals Morphology and Degradation of Multicompartment Microparticles Based on Semi-Crystalline Polystyrene-block-Polybutadiene-block-Poly(L-lactide) Triblock Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4358
Author(s):  
Nicole Janoszka ◽  
Suna Azhdari ◽  
Christian Hils ◽  
Deniz Coban ◽  
Holger Schmalz ◽  
...  
Keyword(s):  
Cross Sections ◽  
Ring Opening ◽  
Particle Diameter ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Selective Degradation ◽  
The Core ◽  
Transmission Electron ◽  
And Control ◽  
Triblock Terpolymers

The confinement assembly of block copolymers shows great potential regarding the formation of functional microparticles with compartmentalized structure. Although a large variety of block chemistries have already been used, less is known about microdomain degradation, which could lead to mesoporous microparticles with particularly complex morphologies for ABC triblock terpolymers. Here, we report on the formation of triblock terpolymer-based, multicompartment microparticles (MMs) and the selective degradation of domains into mesoporous microparticles. A series of polystyrene-block-polybutadiene-block-poly(L-lactide) (PS-b-PB-b-PLLA, SBL) triblock terpolymers was synthesized by a combination of anionic vinyl and ring-opening polymerization, which were transformed into microparticles through evaporation-induced confinement assembly. Despite different block compositions and the presence of a crystallizable PLLA block, we mainly identified hexagonally packed cylinders with a PLLA core and PB shell embedded in a PS matrix. Emulsions were prepared with Shirasu Porous Glass (SPG) membranes leading to a narrow size distribution of the microparticles and control of the average particle diameter, d ≈ 0.4 µm–1.8 µm. The core–shell cylinders lie parallel to the surface for particle diameters d < 0.5 µm and progressively more perpendicular for larger particles d > 0.8 µm as verified with scanning and transmission electron microscopy and particle cross-sections. Finally, the selective degradation of the PLLA cylinders under basic conditions resulted in mesoporous microparticles with a pronounced surface roughness.

scholarly journals Estimation of the chemical specific surface area of catalytic nanoparticles by TEM images analysis

2018 ◽  
Vol 1 (87) ◽  
pp. 5-12 ◽  
Author(s):  
M. Pawlyta ◽  
B. Sobel ◽  
B. Liszka
Keyword(s):  
Fuel Cells ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Platinum Nanoparticles ◽  
Quantitative Methods ◽  
Particle Diameter ◽  
Spherical Particles ◽  
Platinum Particles ◽  
Materials Used

Purpose: The purpose of this article is the development of quantitative methods for assessing the quality of nanocomposite materials used in fuel cells. Design/methodology/approach: latinum is the most commonly used catalyst in fuel cells, commonly in the form of nanoparticles deposited on the surface of carbon black. Due to the nanometric size of platinum particles, transmission electron microscopy can be applied to evaluate the produced catalysts. TEM image also allow to determinate the approximate value of the chemical specific surface area) of platinum nanoparticles, but only in case of spherical particles. Findings: In present work, taking into account additional assumptions resulting directly from the analysis of microscopic images, the method of estimation of the particle diameter and the chemical specific surface area for nonsymmetrical (elongated) nanoparticles is present. Research limitations/implications: The presented work presents a method for determining the specific surface of platinum, when their shape is elongated. It is worth noting that the modified formulas for determining the particle diameter and the value of the chemically active specific surface of the platinum nanoparticles of the elongated shape are equivalent to the formulas previously given for spherical particles, if the particle length and its diameter are equal. In this case, patterns for symmetric particles and more general (modified) patterns can be used interchangeably. Practical implications: Development of new and more effective catalysts for fuel cells. Originality/value: The significance of the presented work results from the possibility of using the described method in the catalyst studies during real catalytic processes. It allows comparing catalytic activity after the process, also in unusual conditions and in an aggressive environment, using minimal amounts of material.

scholarly journals Facile and Green Route to Silver Nanoparticles Using Aqueous Plant Extract, and their Photocatalytic and Antibacterial Studies

2020 ◽  
Vol 26 (4) ◽  
pp. 489-497
Author(s):  
Elias Emenka ELEMIKE ◽  
Damian Cinedu ONWUDIWE ◽  
Tanzim SAIYED ◽  
Anthony Chinonso EKENNIA ◽  
Mayowa Akeem AZEEZ
Keyword(s):  
Silver Nanoparticles ◽  
Plant Extract ◽  
Average Particle Size ◽  
Photocatalytic Property ◽  
Silver Ions ◽  
Cost Effective ◽  
Average Particle ◽  
Welsh Onion ◽  
Characteristic Functional ◽  
Transmission Electron

Silver nanoparticles were prepared through an environmental friendly and cost-effective plant-mediated technique, using crude extracts of Welsh onion plant. The synthesized nanoparticles were characterized using UV-vis spectrophotometer, powdered X-ray diffractometer (p-XRD), Fourier transform infra-red (FTIR) spectrophotometer, and transmission electron microscope (TEM). Silver nanoparticles of different sizes and morphologies were obtained by varying some synthesis parameters such as concentrations of AgNO3 (1, 2 and 5 mM) and ratio of the volume of the plant extract to AgNO3 (1:5 and 1:10) at constant reaction temperature of 80 °C. The difference in the reaction conditions showed significant effects on silver nanoparticles obtained. The surface plasmon resonance (SPR) varied with change in concentration of AgNO3 and the ratio of the AgNO3 to the plant extracts. The lowest SPR appeared around 412 nm (2 mM; 1:10), while the largest was achieved around 427 nm (5 mM; 1:10). FTIR results revealed the presence of different characteristic functional groups responsible for the bioreduction of silver ions in Welsh onion extract. Transmission electron microscopy (TEM) showed that the lowest average particle size of the silver nanoparticles was 3.74 nm (2 mM; 1:10), while the highest was 15.72 nm (1 mM; 1:5). Monodispersed spherical shaped nanoparticles were obtained from the 2 mM concentration of the AgNO3, while particles with some degree of agglomeration were obtained from 1 and 5 mM concentration. The p-XRD studies revealed face centred cubic structures. The nanoparticles obtained from 1 and 5 mM (1:5) gave moderate photo-catalytic potentials in the degradation of methyl red dye. However, the photocatalytic property increased with increase in the concentration of the precursor salt (AgNO3) from 1 to 5 mM. Gram positive Staphylococcus aureus and Bacillus cereus and Gram negative Klebsiela pneumonia and Escherichia coli bacteria strains were susceptible to the silver nanoparticles (2 mM). The nanoparticles were most active against E. coli with a minimum inhibitory concentration (MIC) below 0.05 mg/mL. The silver nanoparticles could become potential compounds in the future antibiotic research.

scholarly journals Characterization and Antimicrobial and Anticancer Properties of Palladium Nanoparticles Biosynthesized Optimally Using Saudi Propolis

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2666
Author(s):  
Maged Al-Fakeh ◽  
Samir Osman Mohammed Osman ◽  
Malek Gassoumi ◽  
Mokded Rabhi ◽  
Mohamed Omer
Keyword(s):  
Electron Microscopy ◽  
Palladium Nanoparticles ◽  
Ductal Carcinoma ◽  
Average Particle Size ◽  
Cost Effective ◽  
Physicochemical Characteristics ◽  
Average Particle ◽  
Propolis Extract ◽  
Anticancer Properties ◽  
Transmission Electron

Due to their unique physicochemical characteristics, palladium nanoparticles (Pd-NPs) have shown tremendous promise in biological applications. The biosynthesis of Pd-NPs employing Saudi propolis has been designed to be environmental, fast, controlled, and cost-effective. The formation and stability of biosynthesized Pd-NPs by Saudi propolis extract were proved by ultraviolet–visible spectrophotometry (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), and Zeta potential analysis. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) findings show that the average particle size of Pd-NPs is between 3.14 and 4.62 nm, which is in quantum scale. The Saudi propolis enhanced the antimicrobial activity against B. subtilis, S. aureus, E. coli, K. pneumoniae, and C. albicans. Pd-NPs show effective anticancer activity against ductal carcinoma (MCF-7) with IC50 of 104.79 µg/mL.

A Review: Klebsiella pneumoniae, Klebisellaoxytoca and Biotechnology

2021 ◽  
Vol 26 (3) ◽  
pp. 2567-2586
Author(s):  
CATERINA TOMULESCU ◽  
◽  
MIȘU MOSCOVICI ◽  
IRINA LUPESCU ◽  
ROXANA MĂDĂLINA STOICA ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Genetic Manipulation ◽  
Klebsiella Oxytoca ◽  
Cost Effective ◽  
Biochemical Properties ◽  
High Yield ◽  
Natural Environments ◽  
Klebsiella Species ◽  
Bulk Chemicals ◽  
Plant Growth Promoting Activities

Biotechnology, molecular biology and genetic engineering, and bioprospecting play a crucial role in our common future, enabling industrially important microorganisms to ensure sustainable products (fuels, chemicals, pharmaceuticals, food, drug delivery systems, medical devices etc.) and new bioeconomic opportunities. Biotechnological applications are able to provide cost-effective green alternatives to conventional industrial processes, which are currently affecting the nature and biodiversity. Klebsiella species are among the well-studied microbes both in medicine field, as ones of the most resilient opportunistic pathogens, and in industry, due to their promising biochemical properties, and their potential as better hosts than other microorganisms, for i.e. in genetic manipulation. Klebsiella oxytoca and Klebsiella pneumoniae are ubiquitously found in natural environments, but also as commensals in the human gut, and associated with a high-resistance to the first-line antibiotics. However, these specific strains are continuously isolated and studied for different industrial purposes (i.e. bulk chemicals and biofuels production, medical diagnosis, nanoparticles and exopolysaccharides synthesis, plant growth promoting activities, bioremediation and biodegradation agents etc.), and scientific results regarding their biotechnological potential could generate big impact for global bioeconomy development. Recently, research in synthetic biology gained a lot of attention, and new techniques highlight ways to reprogramme these microbial cells in view of high-yield or high-quality new chemicals obtainment. Therefore, some scientific research niches are emerging in biotechnology, and unknown metabolic pathways and genes are identified and further studied, to provide alternative solutions to the global challenges.

A Novel Method for the Preparation of Nano-Sized Nickle Powders

2012 ◽  
Vol 512-515 ◽  
pp. 1849-1853 ◽  
Author(s):  
Zhao Han ◽  
Hong Min Zhu
Keyword(s):  
Electron Microscopy ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Chemical Reduction ◽  
Particle Diameter ◽  
Area Measurement ◽  
Average Particle ◽  
Transmission Electron ◽  
20 Nm

Nano-sized nickel powders were prepared through a wet chemical reduction, of NiCl2 by sodium in liquid ammonia at -45 °C, and a subsequent heat-treatment in vacuum at 300 °C. The prepared product was systematically characterized by X-ray diffraction (XRD), scan electron microscopy (SEM), transmission electron microscopy (TEM), and BET specific surface area measurement. The results show that the product was composed of nano-sized nickel particles, with average particle diameter of about 20 nm, and specific surface area of about 30 m2g-1. The possible formation mechanism of the nano-sized nickel powder was also discussed briefly.

Structure and Magnetic Properties of Co, Ni, Mn, Cr and Cu Substituted Magnetites

1998 ◽  
Vol 517 ◽  
Author(s):  
M. Sorescu ◽  
D. Mihaila-Tarabasanu ◽  
L. Diamandescu
Keyword(s):  
Room Temperature ◽  
Random Distribution ◽  
Particle Diameter ◽  
Point Of View ◽  
Site Preference ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Saturation Magnetic Moment ◽  
Transmission Electron ◽  
Transmission Mössbauer Spectroscopy

AbstractCo, Ni, Mn, Cr and Cu substituted magnetites were prepared by the hydrothermal method at 300°C, with concentrations x ranging from 8.2 to 12.5%. Transmission electron microscopy determined the average particle diameter <Φ> to be in the hundred of nm range and the morphological modifications induced by the various substitutions employed. Hysteresis loop measurements were performed to determine the coercive field Hc and saturation magnetic moment ms. While Hc decreased with increasing <Φ>, the particle shape was found to play an important role in explaining the dependence of ms on <Φ>. Transmission Mössbauer spectroscopy was used to determine the site preference of the substitutions and their effect on the hyperfine magnetic fields. The room temperature Mossbauer spectra were analyzed assuming a random distribution of substitutents using the binomial distribution from the ionic crystal point of view. Superparamagnetic particles were observed at room temperature in the case of Cu and Cr substituted magnetites.

High Voltage Transmission Microscopy of Surveyor III Camera Shrouds

1971 ◽  
Vol 29 ◽  
pp. 138-139
Author(s):  
W. R. Duff ◽  
L. E. Thomas ◽  
R. M. Fisher ◽  
S. V. Radcliffe
Keyword(s):  
Alloy Sheet ◽  
Transmission Microscopy ◽  
Television Camera ◽  
Window Method ◽  
Transmission Electron ◽  
Microstructural Effects ◽  
Lunar Environment ◽  
Successful Retrieval ◽  
Materials Used ◽  
Abrasive Paper

Successful retrieval of the television camera and other components from the Surveyor III spacecraft by the Apollo 12 astronauts has provided a unique opportunity to study the effects of a known and relatively extensive exposure to the lunar environment. Microstructural effects including those produced by micro-meteorite impact, radiation damage (by both the solar wind and cosmic rays) and solar heating might be expected in the materials used to fabricate the spacecraft. Samples received were in the form of 1 cm2 of painted unpainted aluminum alloy sheet from the top of the camera visor (JPL Code 933) and the sides (935,936) and bottom (934) of the lower camera shroud. They were prepared for transmission electron microscopy by first hand-grinding with abrasive paper to a thickness of 0.006". The edges were lacquered and the sample electropolished in 10% perchloric methanol using the “window” method, to a thickness of ~0.001". Final thinning was accomplished by polishing 3 mm punched disks in an acetic-phosphoric-nitric acid solution.

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