Sample preparation utilizing sputter coating increases contrast of cellulose nanocrystals in the transmission electron microscope

Microscopy ◽  
2019 ◽  
Author(s):  
Marina R Mulenos ◽  
Bernd Zechmann ◽  
Christie M Sayes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cellulose Nanocrystals ◽  
Particle Aggregation ◽  
Crystalline Cellulose ◽  
Metal Atoms ◽  
Transmission Electron ◽  
Final Layer ◽  
Sputter Coating ◽  
Cellulose Materials

Abstract Cellulose nanocrystals (CNCs) are prepared for transmission electron microscopy (TEM) using positive or negative stains in an effort to increase the contrast between the specimen and background. When imaging CNCs, conventional stains have been shown to induce particle aggregation and produce artifacts. In this study, we report on methods used to image CNCs. To increase contrast and decrease artifacts and aggregation, sputter coating was used to coat the samples. CNCs were loaded onto copper grids and sputter coated with one of four different metals: iridium, carbon, gold, and titanium. The final layer was deposited at 5 nm to ensure surface homogeneity. The thin layer of conductive metal atoms deposited onto the specimen surface significantly increased contrast and improved image quality. The results presented here demonstrate the advantages of using sputter coating for imaging of highly crystalline cellulose materials with TEM.

Cellulose Nanocrystals as Chiral Inducers: Enantioselective Catalysis and Transmission Electron Microscopy 3D Characterization

2015 ◽  
Vol 137 (19) ◽  
pp. 6124-6127 ◽  
Author(s):  
Madhu Kaushik ◽  
Kaustuv Basu ◽  
Charles Benoit ◽  
Ciprian M. Cirtiu ◽  
Hojatollah Vali ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cellulose Nanocrystals ◽  
Enantioselective Catalysis ◽  
Transmission Electron

Synthesis of NiSi2 by 6 MeV Ni implantation into silicon

1988 ◽  
Vol 3 (6) ◽  
pp. 1238-1246 ◽  
Author(s):  
J. K. N. Lindner ◽  
E. H. te Kaat
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Depth Distribution ◽  
Depth Profiling ◽  
Type A ◽  
High Dose ◽  
Metal Atoms ◽  
Transmission Electron ◽  
Defective Layer ◽  
Lattice Planes

Six MeV high-dose Ni implantation into silicon has been applied to synthesize deep-buried metallic layers. These layers have been analyzed by optical reflectivity and spreading resistance depth profiling as well as transmission electron microscopy and cross-section transmission electron microscopy. Already in the as-implanted state, at target temperatures of 450 K and doses above 1017 Ni/cm2, epitaxial precipitates of NiSi2 are formed. They grow in type-A and type-B orientations. In addition to these polyhedral crystallites, thin NiSi2 platelets on {111} lattice planes exist. At a dose of 1.3 × 1018 Ni/cm2, a continuous but highly defective layer of epitaxial NiSi2 is formed by coalescence of mainly type-A precipitates at the maximum of the Ni profile. Investigations indicate that damage gettering of nickel atoms as well as the atomic density increase during implantation influence the depth distribution of implanted metal atoms. Moreover, a suppression of silicon amorphization by nickel is evident.

Methods for preparation of cribellate spider silk fibrils for Transmission Electron Microscopy

1995 ◽  
Vol 53 ◽  
pp. 1076-1077
Author(s):  
B. Cutler
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Osmium Tetroxide ◽  
Spider Silk ◽  
Significant Component ◽  
Fixation Methods ◽  
Transmission Electron ◽  
Sputter Coating ◽  
Formaldehyde Exposure

Spider silk has been examined by transmission electron microscopy (TEM) for over 50 years. A later, more detailed study produced higher resolution images and included a discussion of fixation with osmium tetroxide (OSO4) vapor. The fixation resulted in only minor effects compared to unfixed specimens. Cribellate spiders produce a nonviscous adhesive silk that has as a significant component very fine fibrils produced by a structure called a cribellum. An opportunity to study cribellate silk in a spider family not previously investigated also led to a study of different fixation methods. Immature specimens of Titanoeca nigrella (Chamberlin) (Araneae, Titanoecidae) were collected under rocks at the Cimarron National Grasslands, Morton Co., Kansas. Spiders were kept in the laboratory and spun normal appearing webs. Copper and gold (for OSO4 treatments) 200 m grids were dragged through the webs. All combinations of treatments were used, but formaldehyde exposure always preceded OSO4 exposure which preceded sputter coating. Grids were examined with a JEOL 1200 EXII TEM. An accelerating voltage of 60kv and 100 um objective aperture were used for imaging.

Linear, non-linear and plastic bending deformation of cellulose nanocrystals

2016 ◽  
Vol 18 (29) ◽  
pp. 19880-19887 ◽  
Author(s):  
Pan Chen ◽  
Yu Ogawa ◽  
Yoshiharu Nishiyama ◽  
Ahmed E. Ismail ◽  
Karim Mazeau
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cellulose Nanocrystals ◽  
Deformation Behavior ◽  
Plastic Bending ◽  
Bending Deformation ◽  
Multi Scale ◽  
Scale Modeling ◽  
Transmission Electron ◽  
Multi Scale Modeling

Bending deformation of cellulose nanocrystal is investigated by using multi-scale modeling and transmission electron microscopy, which highlights importance of shear contribution in the deformation behavior of cellulose.

scholarly journals Detection of isolated protein-bound metal ions by single-particle cryo-STEM

2017 ◽  
Vol 114 (42) ◽  
pp. 11139-11144 ◽  
Author(s):  
Nadav Elad ◽  
Giuliano Bellapadrona ◽  
Lothar Houben ◽  
Irit Sagi ◽  
Michael Elbaum
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Metal Ions ◽  
Single Particle ◽  
Dark Field ◽  
X Ray ◽  
X Ray Crystallography ◽  
Metal Atoms ◽  
Transmission Electron ◽  
Structural Methods

Metal ions play essential roles in many aspects of biological chemistry. Detecting their presence and location in proteins and cells is important for understanding biological function. Conventional structural methods such as X-ray crystallography and cryo-transmission electron microscopy can identify metal atoms on protein only if the protein structure is solved to atomic resolution. We demonstrate here the detection of isolated atoms of Zn and Fe on ferritin, using cryogenic annular dark-field scanning transmission electron microscopy (cryo-STEM) coupled with single-particle 3D reconstructions. Zn atoms are found in a pattern that matches precisely their location at the ferroxidase sites determined earlier by X-ray crystallography. By contrast, the Fe distribution is smeared along an arc corresponding to the proposed path from the ferroxidase sites to the mineral nucleation sites along the twofold axes. In this case the single-particle reconstruction is interpreted as a probability distribution function based on the average of individual locations. These results establish conditions for detection of isolated metal atoms in the broader context of electron cryo-microscopy and tomography.

scholarly journals Major Factors Influencing the Size Distribution Analysis of Cellulose Nanocrystals Imaged in Transmission Electron Microscopy

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3318
Author(s):  
Hui Qian
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Cross Section ◽  
Cellulose Nanocrystals ◽  
Staining Method ◽  
Distribution Analysis ◽  
Size Measurement ◽  
Transmission Electron ◽  
Coffee Ring Effect

Size distributions of cellulose nanocrystals (CNCs), extracted from softwood pulp via strong sulfuric acid hydrolysis, exhibit large variability when analyzed from transmission electron microscopy (TEM) images. In this article, the causes of this variability are studied and discussed. In order to obtain results comparable with those reported, a reference material of CNCs (CNCD-1) was used to evaluate size distribution. CNC TEM specimens were prepared as-stained and dried with a rapid-flushing staining method or hydrated and embedded in vitreous ice with the plunge-freezing method. Several sets of bright-field TEM (BF-TEM), annular dark-field scanning TEM (ADF-STEM) and cryogenic-TEM (cryo-TEM) images were acquired for size distribution analysis to study the contributing factors. The rapid-flushing staining method was found to be the most effective for contrast enhancement of CNCs, not only revealing the helical structure of single CNCs but also resolving the laterally jointed CNCs. During TEM specimen preparation, CNCs were fractionated on TEM grids driven by the coffee-ring effect, as observed from contrast variation of CNCs with a stain-depth gradient. From the edge to the center of the TEM grids, the width of CNCs increases, while the aspect ratio (length to width) decreases. This fractionated dispersion of CNCs suggests that images taken near the center of a droplet would give a larger mean width. In addition to particle fractionation driven by the coffee-ring effect, the arrangement and orientation of CNC particles on the substrate significantly affect the size measurement when CNC aggregation cannot be resolved in images. The coexistence of asymmetric cross-section CNC particles introduces a large variation in size measurement, as TEM images of CNCs are mixed projections of the width and height of particles. As a demonstration of how this contributes to inflated size measurement, twisted CNC particles, rectangular cross-section particles and end-to-end jointed CNCs were revealed in reconstructed three-dimensional (3D) micrographs by electron tomography (ET).

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