About Density Gradient Media

The most common means of purifying cells, viruses, subcellular membranes and macromolecules such as protein complexes and lipoproteins is density gradient centrifugation.

Traditionally the separation or purification medium used to purify (fractionate) these particles varies with the type of particle. Cells may be purified using either Percoll® or Ficoll®; viruses with glycerol, sucrose or caesium chloride (CsCl); subcellular membranes with Percoll®, Ficoll® or sucrose; protein complexes with glycerol or sucrose and lipoproteins with potassium bromide (KBr).

Only the Axis-Shield density gradient media OptiPrep™ can be used to purify all these biological particles. Over 100 detailed protocols using OptiPrep™ are available for cell, virus, subcellular membrane, protein complex and lipoprotein fractionation and purification.

OptiPrep™ is a 60% solution of iodixanol. Unlike any of these other gradient media, iodixanol (as an X-ray imaging agent) has been clinically tested and is manufactured under strict FDA and EU cGMP compliance.

OptiPrep™ is the only ready-to-use, general-purpose, density gradient medium with endotoxin levels guaranteed to be <1EU/ml, but routinely determined to be <0.13 EU/ml. It is non-ionic and density gradients can be made isoosmotic.