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Phytosomes: Preparations, Characterization, and Future Uses
Published in Amit Baran Sharangi, K. V. Peter, Medicinal Plants, 2023
Palakdeep Kaur, Uttam Kumar Mandal
Surface morphology and size are important parameters with respect to formulation of phytosomes and they need to be evaluated by suitable microscopic studies. Scanning electron microscope (SEM) is routinely used for this evaluation. However, advanced version of this instrument which is transmission electron microscope (TEM) gives rather accurate results with additional information. In SEM, phytosomal vesicles are coated with a very thin layer of gold and visualized at an appropriate magnification. The spherical shape of the phytosomes can be confirmed through the spherical bulging generally obtained on the surface. TEM studies determine the internal environment in which the drug is entrapped and their distributions within the lipid core is visualized (Semalty et al., 2010; Gupta and Dixit, 2011).
Bioresponsive Hydrogels for Controlled Drug Delivery
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Tamgue Serges William, Dipali Talele, Deepa H. Patel
The scanning electron microscope (SEM) uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. SEM is used to reveal information about sample, surface morphology, chemical composition, and crystalline structure. Areas of approximately 1 cm to 5 microns in width can be imaged in a scanning mode using conventional SEM techniques (magnification ranging from 20X to approximately 30,000X, spatial resolution of 50 to 100 nm). SEM study is usually used also to determine pore size in the sample.
Development of Radiobiology: A Review
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
Several major advances in cellular and molecular biology have markedly influenced the development of radiation biology. For example, the establishment of the mammalian cell line in vitro and the identification of various phases in the life cycle of a cell have increased our understanding of cellular radiosensitivity.8 The study of ultrastructures of a cell by an electronic microscope has been very useful in investigating radiation injuries on a subcellular level. Although radiation-induced changes in the ultrastructures of a cell appear nonspecific, these cellular alterations, in combination with biochemical ones, have increased our understanding of radiation injuries. Radiobiologists have not yet taken advantage of the scanning electron microscope, which shows the surface structure of entire cells in great detail.
Quantification methods for viruses and virus-like particles applied in biopharmaceutical production processes
Published in Expert Review of Vaccines, 2022
Keven Lothert, Friederike Eilts, Michael W. Wolff
Regarding the imaging methods, the application of electron microscopy, i.e. transmission (TEM) and scanning electron microscopy (SEM), has to be mentioned. Investigations by TEM are helpful in virus and VLP productions to confirm the product integrity, if titers were determined only based on antigen contents [139]. As an example, negative staining electron microscopy was successfully applied for counting Influenza A particles [7]. This quantification may be optimized by automation, but the number of counted particles, as well as drawing a conclusion on particle concentrations from the initial sample volume, is rather challenging [157]. Furthermore, due to tedious sample preparation, a highly limited throughput and the considerable costs of appropriate equipment must be taken into account. Consequently, the method might be considered as a niche application, and is only stated in the interest of completeness. A striking benefit, however, is the specificity, as viruses can be identified fairly easily, according to specific visible surface characteristics [44].
Use of electron microscopy to study platelets and thrombi
Published in Platelets, 2020
Maurizio Tomaiuolo, Rustem I. Litvinov, John W. Weisel, Timothy J. Stalker
The study of platelet biology using electron microcopy methods has a long and rich history. It was not long after the introduction of the electron microscope that the first studies of platelet ultrastructure using transmission electron microscopy were published [1]. Conventional electron microscopy is divided into transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In TEM, a beam of electrons is transmitted through a thin section in order to visualize the internal structures. By contrast in SEM, a focused beam of electrons is used to scan the surface of a specimen. A considerable amount of work went into developing the protocols to fix soft tissues so that they could be imaged by electron microscopy, work strongly motivated by the need to visualize tissues and their internal structures in ways that were not possible with any other microscopy technique before. Once the proper fixation protocols had been developed, electron microscopy became instrumental to study platelets, both for basic research [2] and as a diagnostic tool [3]. Today, conventional TEM and SEM approaches remain valuable tools in platelet and thrombosis research, even as EM approaches continue to evolve and new imaging modalities are developed.
Design of experiment (DoE)-driven in vitro and in vivo uptake studies of exosomes for pancreatic cancer delivery enabled by copper-free click chemistry-based labelling
Published in Journal of Extracellular Vesicles, 2020
Lizhou Xu, Farid N. Faruqu, Revadee Liam-or, Omar Abu Abed, Danyang Li, Kerrie Venner, Rachel J Errington, Huw Summers, Julie Tzu-Wen Wang, Khuloud T. Al-Jamal
Freshly isolated exosome particles were used for electron microscopy observation. Scanning electron microscopy (SEM) was performed using FEI Inspect-F (Philips, Eindhoven, the Netherlands) equipment operated at 20 kV. Diluted exosome aliquots were fixed in 5% glutaraldehyde (Sigma-Aldrich) for 2 h and then incubated on the surface of (3-Aminopropyl)triethoxysilane(APTES) (Sigma-Aldrich) pre-treated silicon wafer for 1 h. The sample was then washed with PBS for three times and dehydrated in a series of increasing ethanol concentrations (20, 50, 70, 90, 95, 100%). Samples were then transferred for critical drying (Samdri, Tousimis). The samples were sputter coated with gold before SEM scanning.