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Surface Modification Techniques
Published in S Santhosh Kumar, Somashekhar S. Hiremath, Role of Surface Modification on Bacterial Adhesion of Bio-Implant Materials, 2020
S Santhosh Kumar, Somashekhar S. Hiremath
Physical: During some surface modification processes, such as thermal spraying and physical vapour deposition, chemical reactions do not occur. In this case, the formation of the surface modified layer, films, or coatings on biomaterials is mainly attributed to the thermal, kinetic, and electrical energy. This method includes thermal spray, physical vapour deposition (PVD), ion implantation and deposition, and glow discharge plasma treatment.
Structural Determination of the Polycystin-2 Channel by Electron Cryo-Microscopy
Published in Jinghua Hu, Yong Yu, Polycystic Kidney Disease, 2019
Before mounting the sample onto a transmission electron microscope for imaging, the protein sample has to be spotted onto a solid support and preserved in a native-like, frozen hydrated state within a thin layer of vitreous ice. The cryo-EM sample grids, the solid support, is typically made from copper or gold. A thin layer of amorphous carbon is coated on one side of the copper grid, but often with regularly arrayed perforations (or holes) where a thin layer of vitreous ice with embedded biological molecules will form. As the carbon support film is hydrophobic in nature, a glow discharge treatment is needed to deposit negative charges on the carbon film, thus making it hydrophilic so that the applied protein sample can spread evenly across the grid.
Electrosurgical Principles In Gastrointestinal Endoscopy
Published in John P. Papp, Endoscopie Control of Gastrointestinal Hemorrhage, 2019
All of these events from glow discharge to arc take place at a rate proportional to the voltage across the electrodes and proportional to the current that is allowed to flow through the spark. The greater the voltage used to start the discharge and the greater the current allowed to flow through the discharge, the faster will the process evolve from glow discharge to spark to arc.
Three-dimensional nanofiberous PLLA/PCL scaffold improved biochemical and molecular markers hiPS cell-derived insulin-producing islet-like cells
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Naser Mobarra, Masoud Soleimani, Reza Pakzad, Seyed Ehsan Enderami, Parvin Pasalar
Hybrid random nanofibrous PLLA/PCL scaffolds were built up via electrospinning in Stem Cell Technology Research Center. To the PCL dissolved in a concentration of 8% (w/w) and PLLA 4% (w/w) in chloroform a second solvent N, N-dimethylformamide (DMF) (8:2, v/v) was added, and the mixture was homogenized. After that, a rotating cylindrical drum was used as collector and was placed at a distance of 15 cm from the needle. A high voltage potential (20 kV) was also applied between the needle and the collector. The disposable syringe containing a polymer solution was forced through the needle and was collected as nanofibrous on the rotating cylinder. Oxygen treatment can increase the surface of hydrophilic polymeric nanofibres. The random nanofibrous membranes were separated from the collector surface and treatment with oxygen was performed using a plasma generator with low frequency, 44 KHz, with a cylindrical quartz reactor (Diener Electronics, Germany). Pure oxygen was introduced into the reaction chamber at 0.4 mbar pressures, and then the glow discharge was performed for 3 min. Plasma-treated sheets were punched with a device of 0.5 cm diameter to make a rim which is 0.5 cm in width to the desired size and was sterilized under ethanol 70% for 30 min, and were left overnight in the F12 medium supplemented with 10% calf serum.
Improvement of hepatogenic differentiation of iPS cells on an aligned polyethersulfone compared to random nanofibers
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Maryam Mahmoodinia Maymand, Hamid Reza Soleimanpour-lichaei, Abdolreza Ardeshirylajimi, Masoud Soleimani, Seyed Ehsan Enderami, Shahrzad Nojehdehi, Farkhondeh Behjati, Maryam Kabir Salmani
After scaffold fabrication, surface plasma treatment was performed under optimized conditions of 40 kHz low frequency at 30 w with a cylindrical quartz reactor (Diener Electronics, Germany) by introducing pure oxygen into the reaction chamber at 0.4 mbar pressure and then the glow discharge was applied for 5 min. For collagen grafting, plasma-treated sheets were punched and immersed in 1-ethyl-3–(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS, country) solution (5 mg/mL) for 12 h. Then, the scaffolds were treated with 1 mg/ml collagen I (Advanced Biomatrix, PureCol) solution at 4 °C overnight. Nanofibrous scaffolds (PES/COL) were soaked overnight in culture medium supplemented with 10% serum, 2X pen/strep (Sigma) and 5X amphotericin B (Sigma) at 37 °C.
Quality of extracellular vesicle images by transmission electron microscopy is operator and protocol dependent
Published in Journal of Extracellular Vesicles, 2019
L. G. Rikkert, R. Nieuwland, L. W. M. M. Terstappen, F. A. W. Coumans
TEM preparation protocols for EV samples were selected based on a literature search in Web of Science (Supplemental Data 1). Articles in English published between January 2011 and November 2016 were included. From the 2,602 included articles, we selected authors that are authorities in the EV field based on co-authorship on the MISEV criteria [5], and co-authored at least eight articles which include TEM images of EV samples. From these research groups the most recent protocol was selected. The resulting nine protocols [10–18] are summarised in Table 1. These protocols contain three main elements: (1) fixation to preserve EV morphology, (2) adsorption of EVs to a TEM grid and (3) negative staining to enhance the contrast between EVs and the background. From Table 1, it is clear that each protocol has many variables, and there is no variable similar between protocols. Particularly surprising is the absence or presence of fixation using glutaraldehyde (GA), osmium tetroxide (OsO4) and paraformaldehyde (PFA). Therefore, we selected one protocol of every fixative to evaluate in this study, except OsO4 due to safety regulations of our TEM facility. Furthermore, we also included one protocol which applied UV treatment of the TEM grid to enhance EV adhesion. These protocols are labelled A–D in Table 1. Authors provided additional protocol information upon our request. It should be noted that the grid surface in contact with the sample was always carbon-coated formvar without glow discharge. Even though a thin carbon film or glow discharge may affect the number of EVs and the background quality, we did not apply glow discharge because none of the selected protocols mentioned this.