Difference Between Differential and Density Gradient Centrifugation

The key difference between differential and density gradient centrifugation is that differential centrifugation separates particles in a mixture based on the size of the particles whereas density gradient centrifugation separates particles in a mixture based on the density of the particles.

Centrifugation is a separation method of different components in an analyte mixture. This method involves the rotation of the sample around a fixed axis, which causes the production of a centrifugal force. The centrifugal force causes the particles in the sample to move down through a liquid medium. This process causes the sedimentation of particles or cells with different sizes and densities at different rates.

1. Overview and Key Difference
2. What is Differential Centrifugation
3. What is Density Gradient Centrifugation
4. Side by Side Comparison – Differential vs Density Gradient Centrifugation in Tabular Form
5. Summary

What is Differential Centrifugation?

Differential centrifugation is an analytical technique in which we can separate the particles in a mixture depending on the size of the particle. It is the simplest form of centrifugation and also called differential pelleting. This method is important in separating the components in a cell. Particles having different sizes undergo sedimentation at different rates upon the centrifugation. In other words, large particles sediment faster than smaller particles. Moreover, the sedimentation rate can be increased by increasing the centrifugal force.

When considering its applications, differential centrifugation is useful in harvesting cells or producing crude subcellular fractions from a tissue homogenate. E.g. a liver homogenate contains nuclei, mitochondria, lysosomes, and membrane vesicles. If we centrifuge this homogenate at a low speed and for a short time, we can get the large nuclei as the pellet. If we use high centrifugal force, then we can get mitochondria in the pellet. However, biological samples are always prone to contamination.

What is Density Gradient Centrifugation?

Density gradient centrifugation is an analytical technique in which we can separate the particles in the analyte mixture based on the density of the particle. In this method, the substances are concentrated in a solution of caesium salts or in sucrose. The method involves the fractionation of particles based on buoyancy density. The density gradient in this method is the Caesium salt or the sucrose medium. There are two types of density gradient centrifugation: rate-zonla centrifugation and isopycnic centrifugation.

The rate-zonal centrifugation involves the separation media that has a layered structure with a narrow zone on top of the density gradient. In this process, the particles tend to move at different rates under the centrifugal force depending on the density of the particles. Usually, all the particles produce pellets because the density of the particles is higher than the density gradient.

Isopycnic centrifugation is the second type of density gradient centrifugation method. It starts with a homogeneous solution. Under the centrifugal force, the particles in the analyte mixture move until the density of the particles is similar to the density gradient. Therefore, we can name this technique as equilibrium centrifugation as well.

What is the Difference Between Differential and Density Gradient Centrifugation?

Differential and density gradient centrifugation are two types of centrifugation processes involved in the separation of components in an analyte mixture. The key difference between differential and density gradient centrifugation is that differential centrifugation separates particles in a mixture based on the size of the particles whereas density gradient centrifugation separates particles in a mixture based on the density of the particles.

Below infographic tabulates more differences between differential and density gradient centrifugation.