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%