Percoll® is a well-referenced media for density gradient centrifugation of cells, viruses, and subcellular particles. Percoll® is composed of colloidal silica coated with polyvinylpyrrolidone (PVP).
Percoll® is a low viscosity density gradient medium for preparation of cells, subcellular particles, and larger viruses. The low viscosity of the medium enables cell preparation on preformed gradients in only a few minutes using low centrifugal forces (200 to 1000 × g). The medium is available in easy-to-open, resealable 250 mL and 1 l bottles.
Percoll® consists of silica particles (15 to 30 nm diameter) coated with non-dialyzable polyvinylpyrrolidone (PVP). Free PVP is present at only 1% to 2%. Percoll® is non-toxic, almost chemically inert and does not adhere to membranes. Percoll® gradients can be formed within the density range of 1.0 to 1.3 g/mL, and are iso-osmotic throughout.
Percoll® can be stored unopened at room temperature for five years. At -20° C, it can only be stored for up to six months. If stored at -20° C, gradients form upon thawing, necessitating a mixing of the bottle before use. Preformed gradients can be stored for weeks without a change in gradient shape, provided that the gradient remains unfrozen. Percoll® can be buffered within the pH range 5.5 to 10.0 without any changes in properties. If the pH is dropped below 5.5, gelling may occur. Gelling can also be caused by the presence of divalent cations, an effect which is exacerbated by elevated temperatures.