In Vitro Transmission Electron Microscopy of Water-Borne Dendrimer-Encapsulated Gold Nanoparticles

Increasing evidence suggests that amyloid polymorphism gives rise to different strains of amyloids with distinct toxicities and pathology-spreading properties. Validating this hypothesis is challenging due to a lack of tools and methods that allow for the direct characterization of amyloid polymorphism in hydrated and complex biological samples. Here, we report on the development of 11-mercapto-1-undecanesulfonate-coated gold nanoparticles (NPs) that efficiently label the edges of synthetic, recombinant, and native amyloid fibrils derived from different amyloidogenic proteins. We demonstrate that these NPs represent powerful tools for assessing amyloid morphological polymorphism, using cryogenic transmission electron microscopy (cryo-EM). The NPs allowed for the visualization of morphological features that are not directly observed using standard imaging techniques, including transmission electron microscopy with use of the negative stain or cryo-EM imaging. The use of these NPs to label native paired helical filaments (PHFs) from the postmortem brain of a patient with Alzheimer’s disease, as well as amyloid fibrils extracted from the heart tissue of a patient suffering from systemic amyloid light-chain amyloidosis, revealed a high degree of homogeneity across the fibrils derived from human tissue in comparison with fibrils aggregated in vitro. These findings are consistent with, and strongly support, the emerging view that the physiologic milieu is a key determinant of amyloid fibril strains. Together, these advances should not only facilitate the profiling and characterization of amyloids for structural studies by cryo-EM, but also pave the way to elucidate the structural basis of amyloid strains and toxicity, and possibly the correlation between the pathological and clinical heterogeneity of amyloid diseases.

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A Guide for Using Transmission Electron Microscopy for Studying the Radiosensitizing Effects of Gold Nanoparticles In Vitro

Nanomaterials ◽

10.3390/nano11040859 ◽

2021 ◽

Vol 11 (4) ◽

pp. 859

Author(s):

Ioanna Tremi ◽

Sophia Havaki ◽

Sofia Georgitsopoulou ◽

Nefeli Lagopati ◽

Vasilios Georgakilas ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Gold Nanoparticles ◽

Metallic Nanoparticles ◽

Cellular Localization ◽

Optimal Dose ◽

Enhancement Effect ◽

Nanoparticle Distribution ◽

Transmission Electron

The combined effects of ionizing radiation (IR) with high-z metallic nanoparticles (NPs) such as gold has developed a growing interest over the recent years. It is currently accepted that radiosensitization is not only attributed to physical effects but also to underlying chemical and biological mechanisms’ contributions. Low- and high-linear energy transfer (LET) IRs produce DNA damage of different structural types. The combination of IR with gold nanoparticles may increase the clustering of energy deposition events in the vicinity of the NPs due to the production mainly of photoelectrons and Auger electrons. Biological lesions of such origin for example on DNA are more difficult to be repaired compared to isolated lesions and can augment IR’s detrimental effects as shown by numerous studies. Transmission electron microscopy (TEM) offers a unique opportunity to study the complexity of these effects on a very detailed cellular level, in terms of structure, including nanoparticle uptake and damage. Cellular uptake and nanoparticle distribution inside the cell are crucial in order to contribute to an optimal dose enhancement effect. TEM is mostly used to observe the cellular localization of nanoparticles. However, it can also provide valuable insights on the NPs’ radiosensitization pathways, by studying the biochemical mechanisms through immunogold-labelling of antigenic sites at ultrastructural level under high resolution and magnification. Here, our goal is to describe the possibilities, methodologies and proper use of TEM in the interest of studying NPs-based radiosensitization mechanisms.

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Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079747 ◽

1977 ◽

Vol 35 ◽

pp. 460-461

Author(s):

Tai-Te Chao ◽

John Sullivan ◽

Awtar Krishan

Keyword(s):

Electron Microscopy ◽

Cell Cycle ◽

Transmission Electron Microscopy ◽

Tubulin Polymerization ◽

Vinca Alkaloids ◽

Antimitotic Activity ◽

Transmission Electron ◽

Flow Microfluorometry ◽

Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

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Ethosomes and Transethosomes for Mangiferin Transdermal Delivery

Antioxidants ◽

10.3390/antiox10050768 ◽

2021 ◽

Vol 10 (5) ◽

pp. 768

Author(s):

Maddalena Sguizzato ◽

Francesca Ferrara ◽

Supandeep Singh Hallan ◽

Anna Baldisserotto ◽

Markus Drechsler ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Radical Scavenging ◽

Human Keratinocytes ◽

Antioxidant Response ◽

Correlation Spectroscopy ◽

Inflammatory Status ◽

Transmission Electron ◽

Anti Inflammatory

Mangiferin is a natural glucosyl xanthone with antioxidant and anti-inflammatory activity, making it suitable for protection against cutaneous diseases. In this study ethosomes and transethosomes were designed as topical delivery systems for mangiferin. A preformulation study was conducted using different surfactants in association with phosphatidylcholine. Vesicle dimensional distribution was monitored by photon correlation spectroscopy, while antioxidant capacity and cytotoxicity were respectively assessed by free radical scavenging analysis and MTT on HaCaT keratinocytes. Selected nanosystems were further investigated by cryogenic transmission electron microscopy, while mangiferin entrapment capacity was evaluated by ultracentrifugation and HPLC. The diffusion kinetics of mangiferin from ethosomes and transethosomes evaluated by Franz cell was faster in the case of transethosomes. The suitability of mangiferin-containing nanovesicles in the treatment of skin disorders related to pollutants was investigated, evaluating, in vitro, the antioxidant and anti-inflammatory effect of ethosomes and transethosomes on human keratinocytes exposed to cigarette smoke as an oxidative and inflammatory challenger. The ability to induce an antioxidant response (HO-1) and anti-inflammatory status (IL-6 and NF-kB) was determined by RT-PCR and immunofluorescence. The data demonstrated the effectiveness of mangiferin loaded in nanosystems to protect cells from damage. Finally, to gain insight into the keratinocytes’ uptake of ethosome and transethosome, transmission electron microscopy analyses were conducted, showing that both nanosystems were able to pass intact within the cells.

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Unveiling Growth Pathways of Multiply Twinned Gold Nanoparticles by In Situ Liquid Cell Transmission Electron Microscopy

ACS Nano ◽

10.1021/acsnano.9b10173 ◽

2020 ◽

Vol 14 (8) ◽

pp. 9594-9604

Author(s):

Xiaoming Ma ◽

Fang Lin ◽

Xin Chen ◽

Chuanhong Jin

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Gold Nanoparticles ◽

Transmission Electron ◽

Cell Transmission ◽

Liquid Cell

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Synthesis and Characterization of Water-Soluble Monolayer-Protected Gold Nanoparticles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.617 ◽

2011 ◽

Vol 415-417 ◽

pp. 617-620 ◽

Cited By ~ 1

Author(s):

Yan Su ◽

Ying Yun Lin ◽

Yu Li Fu ◽

Fan Qian ◽

Xiu Pei Yang ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Particle Size ◽

Gold Nanoparticles ◽

Average Particle Size ◽

Water Soluble ◽

Synthesis And Characterization ◽

Average Particle ◽

Transmission Electron

Water-soluble gold nanoparticles (AuNPs) were prepared using 2-mercapto-4-methyl-5- thiazoleacetic acid (MMTA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The AuNPs product was analyzed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the particles were well-dispersed and their average particle size is about 5 nm. The UV-vis absorption and FTIR spectra confirm that the MMTA-AuNPs was stabilized by the carboxylate ions present on the surface of the AuNPs.

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Effects of Different Surfactant Charges on the Formation of Gold Nanoparticles by the LASiS Method

Materials ◽

10.3390/ma14112937 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2937

Author(s):

Muhammad Zulfajri ◽

Wei-Jie Huang ◽

Genin-Gary Huang ◽

Hui-Fen Chen

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Gold Nanoparticles ◽

Laser System ◽

Synthesis Process ◽

Au Nps ◽

Laser Fluences ◽

Transmission Electron ◽

Vis Spectroscopy ◽

532 Nm

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

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Human Islet Amyloid Polypeptide Fibril Binding to Catalase: A Transmission Electron Microscopy and Microplate Study

The Scientific World JOURNAL ◽

10.1100/tsw.2010.73 ◽

2010 ◽

Vol 10 ◽

pp. 879-893 ◽

Cited By ~ 10

Author(s):

Nathaniel G. N. Milton ◽

J. Robin Harris

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Islet Amyloid Polypeptide ◽

Amyloid Β ◽

Human Islet ◽

Islet Amyloid ◽

Human Islet Amyloid Polypeptide ◽

Transmission Electron

The diabetes-associated human islet amyloid polypeptide (IAPP) is a 37-amino-acid peptide that forms fibrilsin vitroandin vivo. Human IAPP fibrils are toxic in a similar manner to Alzheimer's amyloid-β (Aβ) and prion protein (PrP) fibrils. Previous studies have shown that catalase binds to Aβ fibrils and appears to recognize a region containing the Gly-Ala-Ile-Ile sequence that is similar to the Gly-Ala-Ile-Leu sequence found in human IAPP residues 24-27. This study presents a transmission electron microscopy (TEM)—based analysis of fibril formation and the binding of human erythrocyte catalase to IAPP fibrils. The results show that human IAPP 1-37, 8-37, and 20-29 peptides form fibrils with diverse and polymorphic structures. All three forms of IAPP bound catalase, and complexes of IAPP 1-37 or 8-37 with catalase were identified by immunoassay. The binding of biotinylated IAPP to catalase was high affinity with a KDof 0.77nM, and could be inhibited by either human or rat IAPP 1-37 and 8-37 forms. Fibrils formed by the PrP 118-135 peptide with a Gly-Ala-Val-Val sequence also bound catalase. These results suggest that catalase recognizes a Gly-Ala-Ile-Leu—like sequence in amyloid fibril-forming peptides. For IAPP 1-37 and 8-37, the catalase binding was primarily directed towards fibrillar rather than ribbon-like structures, suggesting differences in the accessibility of the human IAPP 24-27 Gly-Ala-Ile-Leu region. This suggests that catalase may be able to discriminate between different structural forms of IAPP fibrils. The ability of catalase to bind IAPP, Aβ, and PrP fibrils demonstrates the presence of similar accessible structural motifs that may be targets for antiamyloid therapeutic development.

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Aquatic Fern (AzollaSp.) Assisted Synthesis of Gold Nanoparticles

International Journal of Nanoscience ◽

10.1142/s0219581x16500083 ◽

2016 ◽

Vol 15 (01n02) ◽

pp. 1650008 ◽

Cited By ~ 4

Author(s):

Anal K. Jha ◽

K. Prasad

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Gold Nanoparticles ◽

Surface Plasmon Resonance ◽

Au Nanoparticles ◽

X Ray ◽

Aquatic Fern ◽

Transmission Electron ◽

Anthraquinone Glycosides ◽

Uv Visible

Aquatic pteridophyte (Azolla sp.) was taken to assess its potential to synthesize the metal (Au) nanoparticles. The synthesized particles were characterized using X-ray, UV-visible, scanning and transmission electron microscopy analyses. Nanoparticles almost spherical in shape having the sizes of 5–17[Formula: see text]nm are found. UV-visible study revealed the surface plasmon resonance at 538[Formula: see text]nm. Responsible phytochemicals for the transformation were principally phenolics, tannins, anthraquinone glycosides and sugars present abundantly in the plant thereby bestowing it adaptive prodigality. Also, the use of Azolla sp. for the synthesis of gold nanoparticles offers the benefit of eco-friendliness.

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Dipetalonema viteae: ultrastructural study on the in vitro interaction between rat macrophages and microfilariae in the presence of IgE antibody

Parasitology ◽

10.1017/s003118200004186x ◽

1981 ◽

Vol 82 (1) ◽

pp. 55-62 ◽

Cited By ~ 8

Author(s):

M. A. Ouaissi ◽

A. Haque ◽

A. Capron

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Ultrastructural Study ◽

Peritoneal Macrophages ◽

Immune Serum ◽

Sequence Of Events ◽

Transmission Electron ◽

Dipetalonema Viteae ◽

In Vitro Interaction

SUMMARYThe in vitro interaction between rat peritoneal macrophages and Dipetalonema viteae microfilariae in the presence of amicrofilaraemic rat immune serum was studied by transmission electron microscopy. The probable sequence of events leading to the killing of D. viteae microfilaria by macrophages is as follows. (a) Rat peritoneal macrophages in the presence of amicrofilaraemic rat immune serum adhere to the parasite surface, (b) the macrophages extend their pseudopodia around the parasite, (c) the ‘lysosome-like’ granules discharge their contents on to the parasite surface, (d) the lytic activity of these products begins at the parasite surface and (e) subsequent breaking of the microfilarial cuticle occurs, exposing the parasite intracellular material.

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