Nycodenz® is an off-white powder, freely soluble in water. Solutions up to 80% (v/w) with a density of 1.426 g/ml can be prepared. Nycodenz® was originally developed as an X-ray contrast medium and has therefore been subjected to rigorous clinical testing. Nycodenz® can be used for the isolation of cells, subcellular organelles and membranes, macromolecules and viruses.

• Nycodenz® is non-ionic, non-toxic to cells and metabolically inert.
• Nycodenz® forms true solutions. It is therefore easy to remove the medium from the cells after fractionation.
• Nycodenz® is resistant to bacterial degradation.
• Nycodenz® solutions can be autoclaved.
• Nycodenz® is the trademark name for iohexol, whose systematic name is 5-(N-2,3-dihydroxypropylacetamido) 2,4,6-tri-iodo-N-N'-bis(2,3-dihydroxypropyl)isophthalamide. It has a molecular weight of 821. The chemical properties and stability of Nycodenz® are related to its structure. Its high density derives from the presence of a substituted triiodobenzene ring linked to a number of hydrophilic groups which are responsible for the high water solubility of Nycodenz®. It is a non-ionic derivative of metrizoic acid; the carboxyl group present in metrizoic acid is linked to the amine group of 3-amino-1,2- propanediol. The dihydroxypropylacetamido side chain is responsible for the very low toxicity of Nycodenz® compared to metrizamide. The iodinated aromatic nucleus absorbs strongly in the ultraviolet region of the spectrum with an absorbtion maximum of 244 nm.
• Gradients of Nycodenz® can be generated by:
  • Diffusion of a discontinuous gradient; simple preparation within 45 minutes.
  • Tilted tube rotation (Gradient Master™).
  • Two-chamber gradient maker.
  • Freezing/thawing of a solution of uniform density.
  • Centrifugation (self-generated gradient).
• The density of Nycodenz® in solution can be determined by measuring the refractive index or it can be calculated from absorbance measurements
• Nycodenz® is a non-colloidal medium therefore the distribution of cells in gradients can be determined using a haemocytometer, electronic particle counter or by light scattering measurements using a spectrophotometer.
• Nycodenz® does not interfere with the orcinol and diphenylamine reactions for the estimation of nucleic acids nor with the very sensitive dye binding assays for protein and DNA.
• Polysaccharides and sugars can be determined in the presence of Nycodenz® using the phenol/H2SO4 assay.
• Fluorimetric assays of nucleic acids and proteins can also be carried out in the presence of Nycodenz®.
• Nycodenz® does not interfere with most assays for the marker enzymes of subcellular components, also commercial scintillants are compatible with Nycodenz®.
• Nycodenz® can be removed from samples by dialysis, ultrafiltration or gel filtration.
• Cells, subcellular organelles and other particulate matter can be isolated from Nycodenz ® by centrifugation without the risk of contaminating the pellet with Nycodenz®.
• Nycodenz® is supplied as a powder