Density Gradient Media and Cell Separation

We offer a complete line of density gradient media for the separation or extraction of leukocytes, viruses, DNA, RNA, organelles as well as many other applications. Our product line includes Histopaque® iodinated gradient media for leukocyte cell separation use in research laboratories, polysaccharides for mammalian cell isolation, colloidal silica media for mammalian cells and organelle isolation, and inorganic salts for the isolation of DNA, viruses and proteins. Featured in this product line is the popular ACCUSPIN System Histopaque®-1077, which uses a 2-chamber tube with a porous frit to separate lymphocytes from whole blood.


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ACCUSPIN and Histopaque®

Cell Separation with ACCUSPIN System-Histopaque® media

The ACCUSPIN system now consists of radiation-sterilized centrifuge tubes specially designed with a porous high-density polyethlyene barrier ("frit") to create two separate chambers. Thanks to this frit, anticoagulated whole blood can be added to the upper chamber without risk of mixing with the Histopaque® separation media contained in the lower chamber.

When centrifuged for 10 minutes, whole blood descends through the frit and contacts the Histopaque® media below the frit. This density grade media allows a clear separation of the blood components. Erythrocytes aggregate and granulocytes become slightly hypertonic, increasing their sedimentation rate which results in pelleting at the bottom of the ACCUSPIN tube. Lymphocytes and other mononuclear cells (i.e., monocytes) remain at the plasma-Histopaque® interface, where they can be easily removed.


ACCUSPIN System-Histopaque®-1077

Featured in our product line is the ACCUSPIN-Histopaque®-1077 system for the purification of lymphocytes and other mononuclear cells.

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ACCUSPIN

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A0561 ACCUSPIN System-Histopaque®-1077 γ-irradiated 50 mL polypropylene tubes fitted with a HDPE porous barrier and aseptically filled with 15 mL of Histopaque 1077. Each tube will separate 15-30 mL of anticoagulated blood.
 
A1805 ACCUSPIN Tubes Sterile, 12 mL Capacity ACCUSPIN Tubes are intended for use with the density gradient separation medium Histopaque® -1077 in the isolation of lymphocytes and other mononuclear cells. Polypropylene radiation sterilized tube fitted with a high density polyethylene barrier. Each tube will accept 3 mL of the density gradient.
Package contains 20 tubes
A2055 ACCUSPIN Tubes Sterile, 50 mL Capacity ACCUSPIN Tubes are intended for use with the density gradient separation medium Histopaque® -1077 in the isolation of lymphocytes and other mononuclear cells. Polypropylene radiation sterilized tube fitted with a high density polyethylene barrier. Each tube will accept 15 mL of the density gradient.
Package contains 10 tubes
A6929 ACCUSPIN System-Histopaque®-1077 γ-irradiated 12 mL polypropylene tubes fitted with a HDPE porous barrier and aseptically filled with 3 mL of Histopaque 1077. Each tube will separate 3-6 mL of anticoagulated blood.
Package contains 40 prefilled tubes
A7054 ACCUSPIN System-Histopaque®-1077 γ-irradiated 50 mL polypropylene tubes fitted with a HDPE porous barrier and aseptically filled with 15 mL of Histopaque 1077. Each tube will separate 15-30 mL of anticoagulated blood.
Package contains 12 prefilled tubes

Histopaque®

Histopaque® iodinated gradient media

Iodinated aromatic compounds, originally devised for x-ray contrast applications, solve the more serious deficiencies of other classes of gradient media. Iodinated gradient media have much lower osmolarities and viscosities than sucrose at any concentration. Polysaccharides, such as Ficoll®, are even more viscous than sucrose at all densities. Ionic gradient media, such as cesium chloride, have higher densities and lower viscosities than other density gradient media. However, their use is restricted due to the high osmolarities and ionic strength which affect the hydration of osmotically sensitive particles and can disrupt or otherwise modify the integrity of biological particles.
Because of their positive properties, iodinated gradient media are used in a wide range of applications. Their structures are usually based on tri-iodobenzoic acid with a hydrophilic group attached to increase solubility.
Histopaque® media are sterile, endotoxin-tested solutions of polysucrose and sodium diatrizoate, adjusted to precise densities. These ready-to-use separation media facilitate the rapid and optimal recovery of viable cells from small volumes of whole blood.

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10771 Histopaque®-1077 sterile-filtered, density: 1.077 g/mL
H8889 Histopaque®-1077 Hybri-Max liquid, sterile-filtered, BioReagent, suitable for hybridoma
10831 Histopaque®-1083 sterile-filtered, density: 1.083 g/mL
11191 Histopaque®-1119 sterile-filtered, density: 1.119 g/mL

Colloidal silica media

Colloidal silica media are not true solutions, but are colloidal suspensions of silica particles coated with polyvinylpyrolidone (PVP) with a diameter of 15-30 nm. The most widely known colloidal silica medium is Percoll®. The polyvinylpyrrolidone minimizes the particle interactions with biology material and stabilized the colloid. Being a colloid, the osmotic strength of Percoll is extremely low and changes little with density. The osmolality of Percoll gradients can be used adjusted by adding appropriate amounts of sucrose or buffer solution. Percoll gradients self-forming when centrifuged in fix-angle rotors (swing out rotors are not satisfactory for self-forming gradients). Percoll can be removes from suspensions by differential pelleting. Percoll gradients are mainly used in isopycnic separations of cell, organelles, membrane vesicles, and even some viruses. The main limitation is that the sample particles size must be larger than the colloidal silica particles, otherwise the particles of silica pellet before the sample bands.

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GE17-0891-01 Percoll® GE Healthcare, 17-0891-01, pack of 1 L
GE17-0891-02 Percoll® GE Healthcare, 17-0891-02, pack of 250 mL
GE17-0891-09 Percoll® GE Healthcare, 17-0891-09, pack of 6 × 1 L
P1644 Percoll® pH 8.5-9.5 (20 °C)
P4937 Percoll® pH 8.5-9.5 (25 °C), cell culture tested
GE17-5445-01 Percoll® PLUS GE Healthcare, 17-5445-01, pack of 1 L
GE17-5445-02 Percoll® PLUS GE Healthcare, 17-5445-02, pack of 250 mL

Inorganic salts

Ionic gradient media, comprised of concentrated heavy metal salts, are almost exclusively used for isopycnic separations of nucleic acids. Cesium chloride and cesium sulfate are the most widely used heavy metal salts with gradient densities of up to 1.91 g/cm3 . Other useful salts include sodium iodide, sodium bromide and the rubidium salts. The steepness and shape of the ionic and non-viscous with high osmolarities. It should be kept in mind that the density of the sample is highly dependent on the sample’s hydration, which in turn depends on the dehydration power of the ionic gradient media.

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C3139 Cesium chloride optical grade, ≥99.5% trace metals basis
C3011 Cesium chloride Grade I, ≥99.0%
C3032 Cesium chloride for molecular biology, ≥99% (silver nitrate titration)
C4036 Cesium chloride for molecular biology, ≥98%
C3309 Cesium chloride BioXtra, ≥99.5% (titration)
C6914 Cesium chloride Grade II, ≥98%
20966 Cesium chloride BioUltra, for molecular biology, ≥99.5% (AT)
C3136 Cesium sulfate Grade I, ≥99%
213233 Lithium chloride ReagentPlus®, 99%
P0838 Potassium bromide BioXtra, ≥99.0%
P9881 Potassium bromide ReagentPlus®, ≥99.0%
60089 Potassium bromide BioUltra, ≥99.5% (AT)
71913 Sodium polytungstate purum p.a., for the preparation of heavy liquid, for sink-float analysis, ≥85% WO3 basis

Nonionic iodinated density gradient media

The iodinated aromatic compounds, originally devised for x-ray contrast applications, solve the more serious deficiencies of the other classes of gradient media. Iodinated gradient media have much lower osmolarities and viscosities than sucrose at any concentration. Polysaccharides such as Ficoll® are even more viscous than sucrose at all densities. Ionic gradient media, such as cesium chloride have higher densities and lower viscosities than other density gradient media. However, their use is restricted due to the high osmolarities and ionic strength which affect the hydration of osmotically sensitive particles and can disrupt or otherwise modify the integrity of biological particles.

Because of their positive properties, iodinated gradient media are used in a wide rage of applications. The structures of most iodinated compounds used as gradient media are based on tri-iodobenzoic acid with a hydrophilic group attached to increase their solubility. The first of these nonionic density gradients, iohexol (e.g., Nycodenz® and Histodenz), became available in the 1970s. Iohexol solutions are more dense at any given concentration than other gradient media types. This means that a lower media concentration is needed for any particular concentration, which minimizes the possibility of biological particles becoming dehydrated. Iohexol is nontoxic and not metabolized by mammalian cells.

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D9268 Diatrizoic acid
D9809 Diatrizoic acid dihydrate meets USP testing specifications
D2158 Histodenz nonionic density gradient medium
M5266 Meglumine diatrizoate
D1556 OptiPrep Density Gradient Medium used for cell and subcellular organelle isolation
S4506 Sodium diatrizoate hydrate ≥98.0%

Polyhydric alcohols

Polyhydric alcohols are considered nonionic gradient media. Some of the first centrifugation techniques developed in the 1950s used sucrose in the purification of cell organelles. Sucrose gradients are widely used for the rate-zonal separation of macromolecules and for the isopycnic separation of viruses and cell organelles. The advantages are its stable nature, inertness and low cost. The disadvantages lie in the fact that concentrated solution is viscous and hypertonic. Reagent-grade sucrose may be contaminated with RNAses or heavy metals and therefore are unsuitable for DNA and RNA purification. Glycerol solution is less dense than corresponding sucrose solutions. However, glycerol solution of the same density of sucrose solutions is much more viscous. Glycerol helps to prevent the activity of certain enzymes and it can be removed through vacuum.

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G5516 Glycerol for molecular biology, ≥99.0%
G6279 Glycerol BioXtra, ≥99% (GC)
G9012 Glycerol ≥99.5%
49767 Glycerol BioUltra, for molecular biology, anhydrous, ≥99.5% (GC)
240850 D-Sorbitol 99%
S1876 D-Sorbitol ≥98%
85529 D-Sorbitol BioUltra, ≥99.5% (HPLC)
S6021 D-Sorbitol for molecular biology, ≥98%
S7903 Sucrose BioXtra, ≥99.5% (GC)
S9378 Sucrose ≥99.5% (GC)
S0389 Sucrose for molecular biology, ≥99.5% (GC)

Polysaccharides

Polysaccharides circumvent the high osmotic strength issues that arise with using sucrose solutions. The most common polysaccharide medium used in Ficoll®. Ficoll is produced by the polymerization of sucrose molecules with epichlorohydrin to give a polysaccharide with the average molecules weight of 400,000. Ficoll solutions below 20%(w/v) have a density of 1.07g/cm3 and are considered osmotically inert. The main disadvantage is Ficoll solutions are more viscous than comparable sucrose solutions.

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D8802 Dextran solution from Leuconostoc mesenteroides 20 % (w/w) (Autoclaved)
D4911 Dextran sulfate sodium salt from Leuconostoc spp. mol wt 6,500-10,000
D6924 Dextran sulfate sodium salt from Leuconostoc spp. average mol wt 9,000-20,000
D6001 Dextran sulfate sodium salt from Leuconostoc spp. average mol wt >500,000 (dextran starting material), contains 0.5-2.0% phosphate buffer, pH 6-8
D8787 Dextran sulfate sodium salt from Leuconostoc spp.
F5415 Ficoll® solution Type 400, 20% in H2O
F9378 Ficoll® 400 Type 400-DL, lyophilized powder
F2637 Ficoll® 400 BioXtra, for molecular biology, lyophilized powder
F8016 Ficoll® 400 lyophilized powder, Type 400-DL, BioReagent, suitable for cell culture
F8636 Ficoll® 400 lyophilized powder, γ-irradiated, BioXtra, suitable for cell culture
F1418 Ficoll® 400 BioXtra, Type 400-DL, lyophilized powder
GE17-1440-02 Ficoll® Paque Plus GE Healthcare, 17-1440-02, pack of 6 × 100 mL
GE17-1440-03 Ficoll® Paque Plus GE Healthcare, 17-1440-03, pack of 6 × 500 mL
GE17-5442-02 Ficoll®-Paque Premium GE Healthcare, 17-5442-02, pack of 6 × 100 mL
GE17-5442-03 Ficoll®-Paque Premium GE Healthcare, 17-5442-03, pack of 6 × 500 mL
GE17-5446-52 Ficoll®-Paque PREMIUM 1.073 GE Healthcare, 17-5446-52, pack of 6 × 100 mL
GE17-5446-02 Ficoll®-Paque PREMIUM 1.084 GE Healthcare, 17-5446-02, pack of 6 × 100 mL
F2878 Ficoll® PM 70 Type 70
P7798 Polysucrose 400 powder
F4375 Ficoll® PM 400 Type 400

Miscellaneous

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F9755 Fluorinert FC-40
F9880 Fluorinert FC-70
Z340391 Gradient Mixer size 15 mL
Z340405 Gradient Mixer size 30 mL
Z340413 Gradient Mixer size 50 mL
Z340421 Gradient Mixer size 100 mL
P1763 Poly(vinyl alcohol) Fully hydrolyzed
1391 Sigma-Sil-A suitable for preparation of TMS derivatives