scholarly journals Low Vacuum Filtration Method as an Alternative Extracellular Vesicle Concentration Method: Comparison with Ultracentrifugation and Differential Centrifugation

2020 ◽  
Author(s):  
Anna Drożdż ◽  
Agnieszka Kamińska ◽  
Magdalena Surman ◽  
Agnieszka Gonet-Surówka ◽  
Robert Jach ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Culture Media ◽  
Membrane Surface ◽  
Method Comparison ◽  
Environmental Scanning Electron Microscopy ◽  
Drug Carriers ◽  
Differential Centrifugation ◽  
Isolation Method ◽  
Filtration Method ◽  
Vacuum Filtration

Recent years brought great focus in the field of development of extracellular vesicles (EVs) based drug-delivery systems. Considering possible applications of EVs as a drug carriers the isolation process is a crucial step. To solve problems related with EV isolation, we created and validated a new EVs isolation method – Low Vacuum Filtration (LVF) and compared it with two commonly applied procedures - differential centrifugation (DC) and ultracentrifugation (UC). EVs isolated from endothelial cells culture media have been characterized by a) transmission electron microscopy (TEM) b) nanoparticle tracking analysis (NTA), c) western blot and d) Fourier-Transform Infrared Spectroscopy (FTIR). Additionally, the membrane surface have been imaged with Environmental Scanning Electron Microscopy (ESEM). We showed that LVF is reproducible and efficient method for EVs isolation form conditioned media. Additionally, we observed correlation between ATR-FTIR spectra quality and the EVs and proteins concentration. ESEM imaging confirmed that actual pore diameter are close to the values calculated theoretically. LVF method is an easy, fast and inexpensive EVs isolation method which allows for isolation of both ectosomes and exosomes from high volume sources with good repeatability. We think that it could be an efficient alternative for commonly applied methods.

scholarly journals Low-Vacuum Filtration as an Alternative Extracellular Vesicle Concentration Method: A Comparison with Ultracentrifugation and Differential Centrifugation

Pharmaceutics ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 872
Author(s):  
Anna Drożdż ◽  
Agnieszka Kamińska ◽  
Magdalena Surman ◽  
Agnieszka Gonet-Surówka ◽  
Robert Jach ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Culture Media ◽  
Membrane Surface ◽  
Environmental Scanning Electron Microscopy ◽  
High Volume ◽  
Drug Carriers ◽  
Attenuated Total Reflection ◽  
Differential Centrifugation ◽  
Isolation Method ◽  
Vacuum Filtration

Recent years have brought great focus on the development of drug delivery systems based on extracellular vesicles (EVs). Considering the possible applications of EVs as drug carriers, the isolation process is a crucial step. To solve the problems involved in EV isolation, we developed and validated a new EV isolation method—low-vacuum filtration (LVF)—and compared it with two commonly applied procedures—differential centrifugation (DC) and ultracentrifugation (UC). EVs isolated from endothelial cell culture media were characterized by (a) Transmission Electron Microscopy (TEM), (b) Nanoparticle Tracking Analysis (NTA), (c) Western blot and (d) Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR-FTIR). Additionally, the membrane surface was imaged with Environmental Scanning Electron Microscopy (ESEM). We found that LVF was a reproducible and efficient method for EV isolation from conditioned media. Additionally, we observed a correlation between ATR-FTIR spectra quality and EV and protein concentration. ESEM imaging confirmed that the actual pore diameter was close to the values calculated theoretically. LVF is an easy, fast and inexpensive EV isolation method that allows for the isolation of both ectosomes and exosomes from high-volume sources with good repeatability. We believe that it could be an efficient alternative to commonly applied methods.

scholarly journals The Preparation and Study of Ethylene Glycol-Modified Graphene Oxide Membranes for Water Purification

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 188 ◽  
Author(s):  
Yang Zhang ◽  
Lin-Jun Huang ◽  
Jian-Guo Tang ◽  
Yao Wang ◽  
Meng-Meng Cheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Graphene Oxide ◽  
Water Purification ◽  
Interlayer Spacing ◽  
Filtration Method ◽  
Vacuum Filtration ◽  
X Ray ◽  
Molecular Separation ◽  
Scanning Electron

In this work, graphene oxide (GO)/ethylene glycol (EG) membranes were designed by a vacuum filtration method for molecular separation and water purification. The composite membranes were characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The interlayer spacing of GO membranes (0.825 nm) and GO/EG membranes (0.634 nm) are measured by X-ray diffraction (XRD). Using the vacuum filtration method, the membrane thickness can be controlled by selecting the volume of the solution from which the membrane is prepared, to achieve high water permeance and high rejection of Rhodamine B (RhB). The membrane performance was evaluated on a dead-end filtration device. The water permeance and rejection of RhB of the membranes are 103.35 L m−2 h−1 bar−1 and 94.56% (GO), 58.17 L m−2 h−1 bar−1 and 97.13% (GO/EG), respectively. The permeability of GO/EG membrane is about 40 × 10−6 L m-1 h−1 bar−1. Compared with the GO membrane, the GO/EG membrane has better separation performance because of its proper interlayer spacing. In this study, the highest rejection of RhB (99.92%) is achieved. The GO/EG membranes have potential applications in the fields of molecular separation and water purification.

Properties of Freestanding Buckypapers with Monodispersion of Multi-Walled Carbon Nanotube Aqueous Solution

2013 ◽  
Vol 765-767 ◽  
pp. 3162-3165 ◽  
Author(s):  
Shao Wei Lu ◽  
Chun Xu Zhang ◽  
Xian Jun Zeng ◽  
Ji Jie Wang ◽  
Peng Nie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotube ◽  
Volume Density ◽  
High Porosity ◽  
Filtration Method ◽  
Vacuum Filtration ◽  
Carbon Nanotube Dispersion ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotube ◽  
Nanotube Dispersion

The monodispersion situation of Multi-walled carbon nanotube dispersion is vital for fabricating high quality MWCNT buckypapers with vacuum filtration method. In this paper, the MWCNT buckypapers were fabricated by surfactants Triton-X100, sonication, centrifugation, vacuum filtration, rinsing and annealing processes. Transmission electron microscopy (TEM) and Zeta potential results show the maximum achievable separation has been reached. The properties of MWCNTs buckypaper can be characterized by Scanning electron microscopy (SEM), a four-point probe, N2 adsorption isotherm, TGA-DSC methods. The results showed that the buckypaper exhibits a low surface and volume density, a high porosity and electric conductivity. The pore diameter is up to 22.02nm, no substantial mass loss below 600°C in air.

scholarly journals Graphene Oxide Films Obtained by Vacuum Filtration: X-Ray Diffraction Evidence of Crystalline Reorganization

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Julia L. S. Gascho ◽  
Sara F. Costa ◽  
Abel A. C. Recco ◽  
Sérgio H. Pezzin
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Interplanar Distance ◽  
Cellulose Membrane ◽  
X Ray Diffraction ◽  
Filtration Method ◽  
Vacuum Filtration ◽  
X Ray ◽  
Transmission Electron ◽  
Oxygen Groups

In this study, films of graphene oxide and chemically or thermally reduced graphene oxide were produced by a simple vacuum filtration method and submitted to a thorough characterization by X-ray diffraction (XRD), Raman and infrared spectroscopies, field-emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy, confocal microscopy, and contact angle measurements. Graphene oxide (GO) was produced from graphite by the modified Hummers method and thereafter reduced with NaBH4 or by heating under argon in a tubular furnace. The films were produced from aqueous solutions by vacuum filtration on a cellulose membrane. Graphite presents two characteristic XRD peaks corresponding to d=0.34 nm and d=0.17 nm. After oxidation, only a peak at d=0.84 nm is found for powder GO, confirming the insertion of oxygen groups with an increase in the interplanar distance of graphene nanoplatelets. However, for GO films, other unexpected peaks are observed at d=0.63 nm, d=0.52 nm, and d=0.48 nm. After reduction, both chemical and thermal, the peak at 0.84 nm disappears, while those corresponding to interplanar distances of 0.63 nm, 0.52 nm, and 0.48 nm are still present. The other characterizations confirm the production and chemical composition of GO and reduced GO films. The results indicate the combination of crystalline regions with different interplanar distances, suggesting the ordering of graphene/graphene oxide intercalated sheets.

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

Sign in / Sign up

Export Citation Format

Share Document