Ficoll ® 400 for molecular biology and biochemistry Ficoll ® 400 is a hydrophilic copolymer of saccharose and epichlorohydrin, that readily solubilises in water and aqueous solutions. It may be solubilised at concentrations of up to 50 %, and is mainly used in the following applications: A) In hybridisation buffer acc. to Denhardt, Ficoll ® 400 reduces non specific binding of labelled DNA to the filter membrane. B) In gel loading buffer it supports DNA application to agarose gels by increasing the density of the sample. C) In continuous or discontinuous density gradients, Ficoll ® 400 is used as matrix for fractioning of cells (e.g. lymphocytes) or subcellular particles, also taking advantage of its ability to stabilise membrane coupled components and the functional as well as the morphological integrity of cells. Autoclavable at neutral pH.