Merck, P4937-500ML, Percoll®

Percoll® is a classic medium for density gradient centrifugation of cells, viruses, and subcellular particles. It consists of colloidal silica particles of 15-30 nm diameter (23% w/w in water), which have been coated with polyvinylpyrrolidone (PVP). The PVP coating renders the product completely non-toxic and ideal for use with biological materials. Due to its heterogeneity in particle size, sedimentation occurs at different rates, spontaneously creating very smooth, isometric gradients in the range of 1.0-1.3 g/ml.