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Axis Schield's Nycodenz® is a non-ionic triiodinated derivative of benzoic acid with three
aliphatic hydrophilic side chains. 

Axis Nycodenz® is the trademark name for Gen's iohexol,
whose systematic name is 5- (N-2, 3-dihydroxypropylacetamido)-2, 4, 6-tri-iodo-N, N'-bis (2, 3 dihydroxypropyl) isophthalamide.

Technical data of analytical grade
Min. content Nycodenz® Min. 98 %
Max. O.D. 420 nm 0.07
H2O (Karl Fischer titration) Max. 5 %
Inorganic iodide Max. 20 µg/g

Nycodenz properties

Axis Shield Nycodenz® has a molecular weight of 821 g/mol and a density of 2.1 g/ml. 

This Nycodenz® is non-ionic, non-toxic and is very water soluble. Stock solutions of over 80 % (w/v) can be prepared.
Nycodenz separation medium is also soluble in formamide and dimethyl formamide, thus it is possible to prepare non-aqueous
denaturing gradients of Nycodenz®. 

Aqueous solutions of Nycodenz® have a very high water activity. Most particles will therefore be fully hydrated in solutions of Nycodenz® and will
band at a low density. Solutions of Nycodenz® are stable to heat and may be autoclaved, stability to autoclaving is enhanced by the addition of small amounts of Tris and EDTA.

Solutions of Nycodenz® are very resistant to bacterial degradation and Nycodenz® is not metabolized by mammalian cells.

The concentration and density of solutions of Nycodenz® can easily be determined by measuring the refractive index. 

Therelationship between concentration, refractive index (n) and density is linear and can be formulated:

  • Concentration, % (w/v) = 607.75 n - 810.13
  • Density (g/ml) = 3.242 n - 3.323

Before using this equation, the refractive index must be corrected for the presence of buffer or salt in the gradient medium.

Nycodenz® is a non-particulate medium; therefore the distribution of cells in a gradient can be determined using a haemocytometer, electronic particle counter or by light-scattering measurements using a spectrophotometer.


Nycodenz® in solid form is stable for a period of 5 years when stored at room temperature and protected from light.

 Nycodenz® in solution is stable for 5 years provided that it is kept sterile and protected from light. Prolonged exposure to direct sunlight leads
to release of iodine from the molecule. 

This effect is negligible when working with these solutions on a day to day basis.


Nycodenz® can be used in the fractionation of nucleic acids, proteins, polysaccharides and nucleoproteins. 

Moreover, most types of subcellular organelles can be successfully isolated on gradients of Nycodenz® under either isotonic or mildly hypertonic
conditions. Nycodenz® has a low osmolality, and is non-toxic, thus making it an ideal medium for the separation of intact living

The low viscosity of Nycodenz® in parallel with it's non-ionic characteristics has proved Nycodenz® to be useful in the isolation
and purification of viruses and bacteria.


Gradients of Nycodenz® can be generated in the following ways:

1. Formed in situ by centrifugation (self-forming
2. Layering solutions of the desired concentration into an
appropriate centrifuge tube and allowing the solutions
to diffuse. Using Nycodenz® isotonic solution gradients
can be simply prepared within 45 minutes (see next
3. Freezing and thawing.
4. Gradient mixers.