scholarly journals A flat embedding method for transmission electron microscopy reveals an unknown mechanism of tetracycline

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Michaela Wenzel ◽  
Marien P. Dekker ◽  
Biwen Wang ◽  
Maroeska J. Burggraaf ◽  
Wilbert Bitter ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Large Scale ◽  
Embedding Method ◽  
Peripheral Membrane Proteins ◽  
Transmission Electron ◽  
Cell Sample ◽  
Flat Embedding ◽  
Induced Changes ◽  
Membrane Deformations

AbstractTransmission electron microscopy of cell sample sections is a popular technique in microbiology. Currently, ultrathin sectioning is done on resin-embedded cell pellets, which consumes milli- to deciliters of culture and results in sections of randomly orientated cells. This is problematic for rod-shaped bacteria and often precludes large-scale quantification of morphological phenotypes due to the lack of sufficient numbers of longitudinally cut cells. Here we report a flat embedding method that enables observation of thousands of longitudinally cut cells per single section and only requires microliter culture volumes. We successfully applied this technique to Bacillus subtilis, Escherichia coli, Mycobacterium bovis, and Acholeplasma laidlawii. To assess the potential of the technique to quantify morphological phenotypes, we monitored antibiotic-induced changes in B. subtilis cells. Surprisingly, we found that the ribosome inhibitor tetracycline causes membrane deformations. Further investigations showed that tetracycline disturbs membrane organization and localization of the peripheral membrane proteins MinD, MinC, and MreB. These observations are not the result of ribosome inhibition but constitute a secondary antibacterial activity of tetracycline that so far has defied discovery.

scholarly journals New flat embedding method for transmission electron microscopy reveals an unknown mechanism of tetracycline

2019 ◽  
Author(s):  
Michaela Wenzel ◽  
Marien P. Dekker ◽  
Biwen Wang ◽  
Maroeska J. Burggraaf ◽  
Wilbert Bitter ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Membrane ◽  
Large Scale ◽  
Public Health Problem ◽  
Fixation Method ◽  
Bacterial Cells ◽  
Embedding Method ◽  
Transmission Electron ◽  
Flat Embedding

AbstractTransmission electron microscopy (TEM) is an important imaging technique in bacterial research and requires ultrathin sectioning of resin embedding of cell pellets. This method consumes milli- to deciliters of culture and results in sections of randomly orientated cells. For rod-shaped bacteria, this makes it exceedingly difficult to find longitudinally cut cells, which precludes large-scale quantification of morphological phenotypes. Here, we describe a new fixation method using either thin agarose layers or carbon-coated glass surfaces that enables flat embedding of bacteria. This technique allows for the observation of thousands of longitudinally cut rod-shaped cells per single section and requires only microliter culture volumes. We successfully applied this technique to Gram-positive Bacillus subtilis, Gram-negative Escherichia coli, the tuberculosis vaccine strain Mycobacterium bovis BCG, and the cell wall-lacking mycoplasma Acholeplasma laidlawii. To assess the potential of the technique to quantify morphological phenotypes, we examined cellular changes induced by a panel of different antibiotics. Surprisingly, we found that the ribosome inhibitor tetracycline causes significant deformations of the cell membrane. Further investigations showed that the presence of tetracycline in the cell membrane changes membrane organization and affects the peripheral membrane proteins MinD, MinC, and MreB, which are important for regulation of cell division and elongation. Importantly, we could show that this effect is not the result of ribosome inhibition but is a secondary antibacterial activity of tetracycline that has defied discovery for more than 50 years.SignificanceBacterial antibiotic resistance is a serious public health problem and novel antibiotics are urgently needed. Before a new antibiotic can be brought to the clinic, its antibacterial mechanism needs to be elucidated. Transmission electron microscopy is an important tool to investigate these mechanisms. We developed a flat embedding method that enables examination of many more bacterial cells than classical protocols, enabling large-scale quantification of phenotypic changes. Flat embedding can be adapted to most growth conditions and microbial species and can be employed in a wide variety of microbiological research fields. Using this technique, we show that even well-established antibiotics like tetracycline can have unknown additional antibacterial activities, demonstrating how flat embedding can contribute to finding new antibiotic mechanisms.

AQUEOUS SYNTHESIS OF HIGH QUANTUM YIELD AND MONODISPERSED THIOL-CAPPED CdxZn1-xTe QUANTUM DOTS BASED ON ELECTROCHEMICAL METHOD

NANO ◽  
2012 ◽  
Vol 07 (02) ◽  
pp. 1250011 ◽  
Author(s):  
JUNWEI LI ◽  
YANG JIANG ◽  
YUGANG ZHANG ◽  
DI WU ◽  
ANQI LUO ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Quantum Yield ◽  
Electrochemical Method ◽  
Large Scale ◽  
Ostwald Ripening ◽  
Visible Absorption ◽  
Aqueous Synthesis ◽  
Transmission Electron

A facile green approach has been developed to control the growth regime in the aqueous synthesis of CdxZn1-xTe semiconductor quantum dots (QDs) based on the electrochemistry method. The Low growth temperature and slow injection of Te precursor are used to prolong the diffusion controlled stage and thus suppress Ostwald ripening during the nanocrystal growth. The experimental results showed that a low concentration of Te precursor will definitely influence the growth procedure. The UV–visible absorption spectra, as well as transmission electron microscopy (TEM) shows the QDs a good monodispersity at any interval of the reaction procedure. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs have high crystallinity and cubic structure. The size and composition-dependent fluorescent emission wavelength of the resultant CdxZn1-xTe alloyed QDs can be tuned from 460 to 610 nm, and their photoluminescent quantum yield can reach up to 70%. Especially in the wavelength range of 510–578 nm, the overall PL QYs of the as-prepared CdxZn1-xTe QDs were above 50%. The current work suggests that electrochemical method is an attractive approach to the synthesis of high-quality II-VI ternary alloyed semiconductor QDs at large-scale with a prominent cost advantage.

Ordering of InGaAs Quantum Dots Grown by Molecular Beam Epitaxy under As2 gas flux

2015 ◽  
Vol 1792 ◽  
Author(s):  
Mourad Benamara ◽  
Yuriy I. Mazur ◽  
Peter Lytvyn ◽  
Morgan E. Ware ◽  
Vitaliy Dorogan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Atomic Force Microscopy ◽  
Molecular Beam Epitaxy ◽  
Large Scale ◽  
Molecular Beam ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTThe influence of the substrate temperature on the morphology and ordering of InGaAs quantum dots (QD), grown on GaAs (001) wafers by Molecular Beam Epitaxy (MBE) under As2 flux has been studied using Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Photoluminescence (PL) measurements. The experimental results show that lateral and vertical orderings occur for temperatures greater than 520°C and that QDs self-organize in a 6-fold symmetry network on (001) surface for T=555°C. Vertical orderings of asymmetric QDs, along directions a few degrees off [001], are observed on a large scale and their formation is discussed.

scholarly journals Growth Mechanism of Periodic-Structured MoS2 by Transmission Electron Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 135
Author(s):  
Arvind Mukundan ◽  
Yu-Ming Tsao ◽  
Sofya B. Artemkina ◽  
Vladimir E. Fedorov ◽  
Hsiang-Chen Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Mechanism ◽  
Large Scale ◽  
Periodic Structures ◽  
Chemical Vapor ◽  
Composition Analysis ◽  
Transmission Electron ◽  
Growth Phenomenon ◽  
Periodic Growth

Molybdenum disulfide (MoS2) was grown on a laser-processed periodic-hole sapphire substrate through chemical vapor deposition. The main purpose was to investigate the mechanism of MoS2 growth in substrate with a periodic structure. By controlling the amount and position of the precursor, adjusting the growth temperature and time, and setting the flow rate of argon gas, MoS2 grew in the region of the periodic holes. A series of various growth layer analyses of MoS2 were then confirmed by Raman spectroscopy, photoluminescence spectroscopy, and atomic force microscopy. Finally, the growth mechanism was studied by transmission electron microscopy (TEM). The experimental results show that in the appropriate environment, MoS2 can be successfully grown on substrate with periodic holes, and the number of growth layers can be determined through measurements. By observing the growth mechanism, composition analysis, and selected area electron diffraction diagram by TEM, we comprehensively understand the growth phenomenon. The results of this research can serve as a reference for the large-scale periodic growth of MoS2. The production of periodic structures by laser drilling is advantageous, as it is relatively simpler than other methods.

Transmission Electron Microscopy of ZnO Nanotube Arrays Etched from Electrodeposited ZnO Nanorods

2008 ◽  
Vol 8 (12) ◽  
pp. 6306-6309 ◽  
Author(s):  
Jun Su ◽  
Renchao Che ◽  
Guangwei She ◽  
Xiaofeng Duan ◽  
Wensheng Shi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Large Scale ◽  
Zno Nanorods ◽  
Growth Direction ◽  
Nanotube Arrays ◽  
Zno Nanotube ◽  
Transmission Electron ◽  
Zno Nanotubes

Well aligned large-scale ZnO nanorods were produced by a simple eletrodeposited process. Then, ZnO nanotubes arrays were formed via a subsequent etching in alkaline solution. Extensive studies including SEM, TEM, EDX, STEM and EELS indicate that the Zn and O elemental composition of the nanorods was well-proportioned along the whole cross section and the ZnO nanotubes were Zn terminated at (0001) polar surface toward the growth direction.

Sonochemical synthesis of large-scale single-crystal PbS nanorods

2003 ◽  
Vol 18 (5) ◽  
pp. 1188-1191 ◽  
Author(s):  
S. M. Zhou ◽  
Y. S. Feng ◽  
L. D. Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystal ◽  
Large Scale ◽  
Three Dimensional ◽  
Ultrasound Irradiation ◽  
Building Blocks ◽  
Uniform Structure ◽  
X Ray ◽  
Transmission Electron

Large-scale single-crystal cubic PbS nanorods were successfully achieved by using ultrasound irradiation in certain ethylenediamine tetraacetic acid (EDTA) solutions, particularly in the solution of Pb:EDTA = 1:1. The obtained PbS nanorods were characterized using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersed x-ray spectrometry, selected area electronic diffraction, and high-resolution transmission electron microscopy. The results reveal that the PbS nanorods with straight and uniform structure have a diameter of about 70–80 nm and length of about 1000 nm, where the growth mechanism is tentatively discussed. The successful synthesis of these cubic structure semiconductor PbS nanorods may open up new possibilities for using these materials as building blocks to create functional two-dimensional or three-dimensional nanostructured materials.

Large Scale Preparation of β-AgVO3 Nanowires Using a Novel Sonochemical Route

2008 ◽  
Vol 8 (6) ◽  
pp. 3203-3207 ◽  
Author(s):  
Changjie Mao ◽  
Xingcai Wu ◽  
Jun-Jie Zhu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Lithium Ion Batteries ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Lithium Ion ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

A large number of β-AgVO3 nanowires with diameter of 30–60 nm, and length of 1.5–3 μm have been successfully synthesized by a simple and facile low-temperature sonochemical route. The morphologies and structures of the nanowires were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning transmission electron microscopy (SEM), and thermal gravimetric analysis (TGA). Cyclic voltammetry and charge–discharge experiments were applied to characterize the electrochemical properties of the nanowires as cathode materials for lithium-ion batteries. In the initial discharge and charge process, the as-prepared β-AgVO3 nanowires showed the initial charge and discharge capacities of 69 and 102 (mAh)/g, respectively. It is anticipated that the β-AgVO3 nanostructures are promising cathode candidates in the application of primary lithium-ion batteries.

Large Scale Combustion Synthesis of Single-Walled Carbon Nanotubes and Their Characterization

2008 ◽  
Vol 8 (11) ◽  
pp. 6065-6074 ◽  
Author(s):  
Henning Richter ◽  
Meri Treska ◽  
Jack B. Howard ◽  
John Z. Wen ◽  
Sebastien B. Thomasson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Transmission Electron Microscopy ◽  
Combustion Synthesis ◽  
Large Scale ◽  
Single Walled Carbon Nanotubes ◽  
Process Conditions ◽  
Single Walled Carbon ◽  
Transmission Electron ◽  
Walled Carbon Nanotubes

Since its invention in 1991, premixed combustion synthesis of fullerenic materials has been established as the major industrial process for manufacturing of these materials. Large-scale production of fullerenes such as C60, C70 and C84 has been implemented. More recently, combustion technology has been extended to the targeted synthesis of single-walled carbon nanotubes (SWCNT). Addition of catalyst precursor and operation at well-controlled fuel-rich but non-sooting conditions are required. Extensive parametric studies have allowed for the optimization of the formation of high-quality SWCNT. Purification techniques previously reported in the literature have been adjusted and used successfully for the nearly complete removal of metal and metal oxide. Material has been characterized using Raman spectroscopy, scanning (SEM) and transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Correlations between process conditions and nanotube properties such as length have been established. Product reproducibility and process scalability of the combustion process have been demonstrated. Sample preparation was found to affect significantly the apparent characteristics of nanotubes as seen in electron microscopy images.

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