The “rediscovery” of polyethylene glycol, and its use as an embedding matrix

1984 ◽  
Vol 42 ◽  
pp. 28-31
Author(s):  
J. J. Wolosewick
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Light And Electron Microscopy ◽  
Polyethylene Glycols ◽  
Frozen Sections ◽  
Solid Polymers ◽  
Standard Procedures ◽  
Peg 4000

Polyethylene glycols are liquid or solid polymers of the general formula H(OCH2CH2)nOH, where n is greater than or equal to 4. They are readily miscible in water and in a variety of solvents and are nontoxic. The higher molecular weight polymers (e.g., PEG 4000, 6000) are brittle and melt at 55°-65°C, while the lower molecular weight polymers are soft gummy solids or liquids. These polymers have been used as embedding matrices for light and electron microscopy since the 1940's, although their use has been overshadowed by the now standard embedments (e.g., paraffin and epoxy resins).The procedures for embedding in PEG have been described in detail. Briefly, specimens are fixed according to standard procedures, washed in an appropriate buffer, dehydrated either in PEG-H2O solutions, or in ethyl alcohol. For embedding, the specimens are transferred to capsules filled with the pure polymer and solidified at room temperature, or by rapid cooling in liquid nitrogen. The blocks are mounted onto suitable stubs (e.g., Epon blanks), trimmed and sectioned “dry” on glass or diamond knives. The sections are mounted onto polylysine-coated slides or Forrmvar-coated grids in the same manner as are frozen sections.

Effect of Various Curing Agents On the Chemical Stability of Epoxy Resins

CORROSION ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 11t-20t ◽  
Author(s):  
RONALD L. DeHOFF
Keyword(s):  
Molecular Weight ◽  
Chemical Stability ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Curing Agent ◽  
Corrosion Prevention ◽  
Curing Agents ◽  
Outdoor Weathering ◽  
Better Than

Abstract The epoxy resins most widely used in corrosion prevention are liquids of low molecular weight which can be converted to hard, tough, chemically resistant polymers by the use of various curing agents. Unlike other thermosetting resins such as polyesters, the curing agents may produce chemical linkages in the final polymers that differ from those present in the uncured form. Hence, the properties of cured epoxy resins are likely dependent upon, and may even reflect the properties of the curing agent used. Some seven different epoxy resin systems were exposed to various chemical environments and evaluatd for changes in dimensional stability and flexural strengths over a six month period. From the data presented herein, only limited conclusions may be drawn. Heat cured systems fare better than room temperature cured systems in every case. Anhydride cured epoxy resins show greater resistance to outdoor weathering than amine cured systems. 5.4.5, 6.6.8

scholarly journals Comparative studies of hydration behaviour and density of Pyrrolidone K-30, PEG 6000 and PEG 20000

2015 ◽  
Vol 18 (1) ◽  
pp. 48-52
Author(s):  
Sakina Sultana ◽  
Md Ohidullah ◽  
AHM Saifuddin ◽  
Md Saddam Hossain
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Comparative Studies ◽  
Room Temperature ◽  
Linear Trend ◽  
Density Measurement ◽  
Pharmaceutical Journal ◽  
Polyethylene Glycols ◽  
Peg 6000 ◽  
Hydration Behaviour

A comparative study was conducted on aqueous solutions of Pyrrolidone K-30 and Polyethylene glycols of molecular weight 6000 and 20000, respectively for investigating their hydration behaviour in terms of intrinsic viscosity and density. In the study, Pyrrolidone K-30 exhibited the intrinsic viscosity of ~14 g/ml, while PEG 6000 and PEG 20000 revealed the intrinsic viscosities of 18 g/ml and 28 g/ml, respectively at a room temperature of 298 ± 1º K. Thus, among these three compounds PEG 20000 exhibited the highest intrinsic viscosity which was interesting. In density measurement this compound showed a non-linear trend of change in density as concentration was varied. Such results were opposite to that observed with the remaining two compounds.Bangladesh Pharmaceutical Journal 18(1): 48-52, 2015

scholarly journals Fluorescence-Based Detection of Membrane Fusion State on a Cryo-EM Grid using Correlated Cryo-Fluorescence and Cryo-Electron Microscopy

2019 ◽  
Vol 25 (4) ◽  
pp. 942-949 ◽  
Author(s):  
Lauren Ann Metskas ◽  
John A. G. Briggs
Keyword(s):  
Electron Microscopy ◽  
Membrane Fusion ◽  
Room Temperature ◽  
Light And Electron Microscopy ◽  
Lipid Vesicles ◽  
Morphological Description ◽  
Spectral Shifts ◽  
Cryo Electron Microscopy ◽  
State Duration ◽  
Fusion Applications

AbstractCorrelated light and electron microscopy (CLEM) has become a popular technique for combining the protein-specific labeling of fluorescence with electron microscopy, both at room and cryogenic temperatures. Fluorescence applications at cryo-temperatures have typically been limited to localization of tagged protein oligomers due to known issues of extended triplet state duration, spectral shifts, and reduced photon capture through cryo-CLEM objectives. Here, we consider fluorophore characteristics and behaviors that could enable more extended applications. We describe how dialkylcarbocanine DiD, and its autoquenching by resonant energy transfer (RET), can be used to distinguish the fusion state of a lipid bilayer at cryo-temperatures. By adapting an established fusion assay to work under cryo-CLEM conditions, we identified areas of fusion between influenza virus-like particles and fluorescently labeled lipid vesicles on a cryo-EM grid. This result demonstrates that cryo-CLEM can be used to localize functions in addition to tagged proteins, and that fluorescence autoquenching by RET can be incorporated successfully into cryo-CLEM approaches. In the case of membrane fusion applications, this method provides both an orthogonal confirmation of functional state independent of the morphological description from cryo-EM and a way to bridge room-temperature kinetic assays and the cryo-EM images.

Developmental stages of Cyclospora talpae in the liver and bile duct of the mole (Talpa europaea)

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 345-350 ◽  
Author(s):  
H. A. Mohamed ◽  
D. H. Molyneux
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Bile Duct ◽  
Epithelial Cells ◽  
Room Temperature ◽  
Mononuclear Cells ◽  
Developmental Stages ◽  
Light And Electron Microscopy ◽  
Ultra Structure ◽  
Talpa Europaea

SUMMARYThe completed life-cycle of Cyclospora talpae, an extra-intestinal coccidian (Apicomplexa) of the liver of the mole (Talpa europaea). is reported. Oocysts sporulated within 12–14 days at room temperature (20–22 °C). Both macro- and micro-gametocytes developed independently within the nucleus of epithelial cells lining the bile duct as demonstrated by both light and electron microscopy. Merogony was seen in the mononuclear cells in the capillary sinusoids of the liver. Merozoites showed the typical ultrastructural features of the Apicomplexa. The life-cycle of C. talpae and the ultra-structure of the gametogonic and merogonic stages are reported; the ultrastructure of the merozoites is reported as the first description of this stage for the genus Cyclospora.

Freezing without Ice Crystal Damage: Semithin and Ultrathin Frozen Sections of Ethanol-Infiltrated Tissue for Microscopy, with Applications to Immunocytochemistry

1995 ◽  
Vol 1 (5) ◽  
pp. 217-230
Author(s):  
A. Kent Christensen ◽  
Terry B. Lowry
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light And Electron Microscopy ◽  
Ice Crystal ◽  
Freezing Damage ◽  
Frozen Sections ◽  
Glass Slides ◽  
Frozen Tissue ◽  
Crystal Damage ◽  
Ultrathin Frozen Sections

Ethanol (ethyl alcohol) has long been a standard reagent used in preparing tissues for light and electron microscopy. After fixation, tissues are usually dehydrated with ethanol before being embedded in paraffin or plastic. In this study we show that the ethanol-infiltrated tissue can be frozen and sectioned directly without embedding. When tissue impregnated with ethanol is cooled below about −117°C with liquid nitrogen, the ethanol solidifies without appreciable crystallization. The frozen tissue can then be sectioned in a commercial cryoultramicrotome that is set at −155 to −170°C to produce semithin frozen sections (0.5 to 3 μm thick) for light microscopy or ultrathin frozen sections (50 to 100 nm thick) for electron microscopy. Sections are picked up and mounted on glass slides or EM grids by means that are in current use for ice ultrathin frozen sectioning. Because there is no apparent freezing damage, the morphology in these ethanol frozen sections of unembedded tissue appears generally quite good, often resembling that obtained by conventional EM techniques. Examples are provided that illustrate the use of this material for immunocytochemistry at the light and electron microscope levels.

Simultaneous observations of immunolabeled frozen sections in lm and em

1978 ◽  
Vol 36 (2) ◽  
pp. 164-165
Author(s):  
K. T. Tokuyasu ◽  
J. Slot ◽  
S. J. Singer
Keyword(s):  
Electron Microscopy ◽  
Fluorescent Microscopy ◽  
Light And Electron Microscopy ◽  
Frozen Sections ◽  
Cover Glass ◽  
Rat Pancreas ◽  
Light Microscopic Observation ◽  
Rabbit Igg ◽  
Ultrathin Frozen Sections ◽  
Number Of Cells

Immunofluorescent microscopy is more suitable for the analysis of a large number of cells, often greater in the sensitivity for the detection of antigens, and more readily applicable for the identification of multiple antigens than immunoe1ectron microscopy. For combining these features of fluorescent microscopy with the superior resolution of electron microscopy, we attempted to observe the same immunolabeled ultrathin frozen sections with both light and electron microscopy.Ultrathin frozen sections of rat pancreas fixed in a mixture of 2% formaldehyde and 0.2% g1utaraldehyde for 1 hr at 4°C were first immunostained with rabbit anti-rat amylase antibodies, then very lightly with ferritin-goat anti-rabbit IgG conjugates and heavily with rhodamine-goat anti-rabbit IgG conjugates. For light microscopic observation, grids were suspended underneath the cover glass with a very thin layer of 50-90% glycerol and the cover glass was separated from the slide glass by a spacer to avoid the contact of the grid with the slide glass. After the light microscope observation, the grids were floated on 0.1 M phosphate buffer by dissolving glycerol into the buffer and processed for electron microscopy.

scholarly journals Method for epitope selection of antisera for immunohistology.

1989 ◽  
Vol 37 (2) ◽  
pp. 273-276 ◽  
Author(s):  
D Wedlich
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Antigen Detection ◽  
Frozen Sections ◽  
Fixed Tissue ◽  
Nitrocellulose Filter ◽  
Epitope Selection ◽  
Immunohistological Analysis ◽  
Polyclonal Serum ◽  
Selection Of

Polyclonal anti-laminin serum was affinity-purified on paraformaldehyde-fixed laminin on a nitrocellulose filter. The purified antibodies were tested for their specificity in immunohistological stainings on frozen sections of paraformaldehyde-fixed tissue. As compared to the initial polyclonal serum, the purified antibodies increased the specificity of antigen detection, since all background caused by nonspecific reactions was eliminated. This technique promises to be very useful for immunohistological analysis using light and electron microscopy.

Polarized-light and electron microscopy study of the static domain structure of ferroic Fe3B7O13I boracite at room temperature

2018 ◽  
Vol 534 (1) ◽  
pp. 73-80 ◽  
Author(s):  
A. G. Castellanos-Guzmán ◽  
O. Jiménez ◽  
C. Miramontes-Corona ◽  
D. Mendoza-Anaya ◽  
O. R. Camacho ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Domain Structure ◽  
Room Temperature ◽  
Light And Electron Microscopy ◽  
Polarized Light ◽  
Microscopy Study ◽  
Electron Microscopy Study

scholarly journals Rapid low molecular weight polyethylene glycol embedding protocol for immunocytochemistry.

1989 ◽  
Vol 37 (10) ◽  
pp. 1549-1552 ◽  
Author(s):  
J Mowery ◽  
J Chesner ◽  
S Spangenberger ◽  
D C Hixson
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Fixed Tissue ◽  
Thin Sectioning ◽  
Membrane Antigens ◽  
Excellent Preservation ◽  
Peg 600

We describe an alternative polyethylene glycol (PEG) embedding procedure which utilizes PEG 200 for dehydration and PEG 600 for infiltration and embedding of perfusion-fixed rat liver. PEG 600 has a melting point of 22 degrees C, enabling infiltration of fixed tissue to be performed at room temperature. Sections (2 microM) cut in a cryostat at -20 degrees C and immobilized in agarose were readily labeled by immunoperoxidase protocols with monoclonal antibodies to hepatocyte membrane antigens. Subsequent examination by light microscopy or by electron microscopy after re-embedding in resin and ultra-thin sectioning showed excellent preservation of morphology, with minimal impairment of antigenicity.

Sign in / Sign up

Export Citation Format

Share Document