Counterflow centrifugation takes its name from the opposing forces within and around the instrument’s chamber as they flow against each other. CCE involves passing a cell suspension through a chamber containing a dense liquid medium, flowing at a constant and controlled rate. As the cells flow through the chamber, smaller particles are pushed out of the compartment and larger particles are kept within the circulating liquid medium.
The buffer’s constant flow rate is integral to this method’s underlying physics and functionality. The inner chamber increases rotational speed against the constant flow of the liquid, resulting in a gradual increase in sedimentation rate. By maintaining a constant flow rate of buffer and an opposing centrifugal force, the density of the chamber increases.
As the cells in suspension move outward within the chamber, the cells or particles are exposed to changing centrifugal force proportional to the distance from the chamber’s center. The cells separate according to their sedimentation properties. Larger particles sediment more rapidly than smaller particles and are collected at a higher centrifugal force and can be collected in fractions as they exit the chamber. The separated cells are pushed from the chamber by size and density, which is useful for isolating various cell populations.