Identifying Nanotoxicity at the Cellular Level Using Electron Microscopy
Suresh C. Pillai, Yvonne Lang in Toxicity of Nanomaterials, 2019
One must first consider the concept of resolution to truly understand the power of the electron microscope. Resolution can be defined as the ability of an optical microscope to distinguish detail and is related to the numerical aperture, or light gathering ability of the lens, and the wavelength of light used (Weakley, 1972). Unaided, the human eye can distinguish clearly two points that are approximately 0.2 millimetres (mm) apart from one another. If the points are closer to one another, they appear as a single blurry dot. Light microscopy affords a resolution of approximately 0.2 micrometres (µm), whilst electron microscopy allows objects to be resolved down to the nanometre (nm) scale (approximately 1 nm) or, in a biological context roughly the size of some cellular organelles (Perkins et al., 2009). It is predominantly for this reason that electron microscopy is one of the most useful techniques to study nanotoxicity at the cellular level. The high-magnification, high-resolution images allow the observer to analyse the intricacies of tissue, cellular, and subcellular environments in detail.
Wide-angle viewing systems for vitreoretinal surgery
A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha in Vitreoretinal Surgical Techniques, 2019
The microscope light is turned off when endoillumination is used. The SDI pedal is activated. The microscope is slowly lowered using the coarse and then the fine vertical movement. The knurled knob on the BIOM device should be started approximately 0.5–1 inch below its highest setting for most eyes. Turning the knob counterclockwise so that the objective lens elevates will focus down, whereas turning the knob clockwise lowers the objective lens closer to the cornea and focuses upward. Focusing should be practiced with endoillumination aimed at the disc and low levels of magnification zoom should be used. Maneuvering to see the periphery requires that the globe be tilted slightly in the direction of X –Y movement to gain maximum visualization. Globe integrity in these extreme positions can be enhanced further by elevating the height of the bottle. In general, we recommend a low bottle height for most portions of the surgical procedure, because this decreases the risk of corneal edema and vascular compromise. Magnification is achieved by using the zoom system of the operating microscope or by lowering the microscope (microscope focus) so that the objective lens is closer to the cornea.
Fundamental Techniques Of Microvascular Anastomosis
Waldemar L. Olszewski in CRC Handbook of Microsurgery, 2019
Figure 1 shows the Zeiss® OPMi-6 fiberoptic diploscope which was very recently installed in our new operating theater. It has recently been remodeled from the standard OPMi-6 for neurosurgery or ENT [ear-nose-throat (oto-rhino-laryngology)] use to a diploscope, which is quite similar to the OPMi-7 for orthopedic and plastic surgery. This microscope, with an electromotive ceiling mount, has motorized zoom magnification and zoom focusing controlled by a foot switch. In addition to preserving several merits of the original OPMi-6, such as the ability to focus without losing sight of the operating field when the microscope is tilted, modern accessories such as a tilting system for the binocular tubes (which can be tilted through an arc of 60°) and a X-Y coupling which allows horizontal movements with the foot control are attached to this model. This type of microscope is much better than the OPMi-7 in its movability and handling of the scope. If the eyepieces with 12.5 × magnifications and the objective lens with a 200-mm focusing distance and 160-mm optical tube length are mounted on this microscope, a range of magnification factors from 0.5 to 2.5 will give a series of variable magnifications from 6.25 to 31.25 × — optical tube length/focusing distance × 12.5 × magnification factors = actual magnification.
Metformin pretreatment suppresses alterations to the articular cartilage ultrastructure and knee joint tissue damage secondary to type 2 diabetes mellitus in rats
Published in Ultrastructural Pathology, 2020
Amal F. Dawood, Norah Alzamil, Hasnaa A. Ebrahim, Dina H. Abdel Kader, Samaa S. Kamar, Mohamed A. Haidara, Bahjat Al-Ani
Knee joints were dissected and fixed with 10% formalin for 72 hours then decalcified using 5% hydrochloric acid for 3 weeks. The decalcified specimens were dehydrated in ascending grade of alcohols and paraffin embedding using standard methods. Knee joint specimens were then sectioned in sagittal plane with 5 μm thickness and were stained with H&E and safranin o fast green, and analyzed to elucidate the status of tissue architecture and pathological analysis. Microscopic images were acquired using light microscopy. Safranin o fast green staining was then used to evaluate the proteoglycans content in the articular cartilage. Histological assessment of the articular cartilage was performed according to the modified method that determine the grading system for osteoarthritic changes in the cartilage.24 The grading estimates the depth of the biologic progression of the osteoarthritic process into the cartilage. It depends on the assessment of the cartilage structure and surface, cellularity, Safranin-O fast green staining and tide mark integrity. Grade 0 represents normal cartilage, while grade 6 indicates the most severe cartilage degeneration. The mean of each group’s grade was then used as an overall score.25
Genotoxicity induced by metal oxide nanoparticles: a weight of evidence study and effect of particle surface and electronic properties
Published in Nanotoxicology, 2018
Azadi Golbamaki, Nazanin Golbamaki, Natalia Sizochenko, Bakhtiyor Rasulev, Jerzy Leszczynski, Emilio Benfenati
There is a lack of standardized methodologies or regulatory protocols for detection or characterization of NM. Lin et al. (2014) in their review summarize the techniques that are commonly used to study the size, shape, surface properties, composition, purity, and stability of NM, along with their advantages and disadvantages. They report the analytical modalities for evaluation of the physicochemical characteristics of NM and their strengths and limitations. We have analyzed collected data using analytical modalities suggested by Lin et al. (2014). Several types of microscopy technologies are reported in the investigated literature and we have extracted the corresponding information for each paper. These technologies included the following: transmission electron microscope (TEM), scanning electron microscope (SEM), atomic force microscopes (AFMs), X-ray diffraction (XRD), scanning tunneling microscope (STM), Brunauer, Emmett and Teller (BET), and dynamic light scattering (DLS). Chadha et al. (2012) published more information on microscopy technologies. Our analysis shows that 53 metadata reported analysis performed using DLS in water and medium, 47 metadata reported characterization using TEM, 15 XRD, 9 BET and 7 SEM. In our analysis, we observed that majority of papers did not report studies of agglomeration (Table S1-A), although an important step in the characterization of NM.
Surface-modified polymeric nanoparticles for drug delivery to cancer cells
Published in Expert Opinion on Drug Delivery, 2021
Arsalan Ahmed, Shumaila Sarwar, Yong Hu, Muhammad Usman Munir, Muhammad Farrukh Nisar, Fakhera Ikram, Anila Asif, Saeed Ur Rahman, Aqif Anwar Chaudhry, Ihtasham Ur Rehman
Microscopic studies are conducted to elucidate the morphology and topography of nanoparticles. The structural information clarifies other features such as hydrophobicity, agglomeration, and interaction with cells. In microscopic imaging techniques, two main approaches are employed to obtain a real image of the sample. First, the sample surface is scanned point by point using a probe beam of smaller diameter. Examples of this category are Scanning electron microscope (SEM), field emission SEM (FESEM), Scanning tunneling microscope, and scanning probe microscope (SPM). Second, the surface is illuminated with electron beam, and a direct image is obtained via the optical path of instrument. Representative examples of this type include optical microscopy and transmission electron microscopy (TEM) [138]. In electron microscopy, SEM or FESEM provide two-dimensional imaging, which could provide information about size, shape, distribution, and hierarchy of surface features of polymeric nanoparticles. Furthermore, Atomic force microscopy (AFM), an example of SPM, can give three-dimensional imaging. It also determines the size, morphology, surface texture, roughness, distribution, and nanoparticle volume [139].
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