Other meanings of Centrifugation
Laboratory Techniques
Centrifugation is a laboratory technique that uses centrifugal force to separate mixtures based on density, size, or shape. It is fundamental in biochemistry, molecular biology, and clinical diagnostics for isolating cells, organelles, proteins, and nucleic acids. The technique relies on spinning samples at high speeds, causing denser components to sediment faster than less dense ones.
Centrifugation exploits the sedimentation of particles under a centrifugal field. The sedimentation rate depends on particle size, density, and the applied centrifugal force, described by the Svedberg equation. Differential centrifugation separates by sequential pelleting at increasing speeds, while density-gradient centrifugation uses a medium like sucrose or cesium chloride to separate by buoyant density. Isopycnic centrifugation achieves separation solely by density, independent of time. Ultracentrifugation, operating above 100,000×g, can sediment macromolecules and viruses.1
Centrifugation is indispensable in isolating subcellular fractions, such as mitochondria and nuclei, for biochemical analysis. In clinical settings, it separates blood components for transfusion or diagnostic testing. It is also used to purify viruses, plasmids, and recombinant proteins. Density-gradient centrifugation is key in preparing purified organelles and in the isolation of exosomes. In industrial biotechnology, centrifugation clarifies fermentation broths and harvests cells.2
Centrifuges range from small benchtop models to large floor-standing ultracentrifuges. Rotors are either fixed-angle or swinging-bucket, each with specific applications. Safety is critical: imbalance can cause rotor failure, and aerosols must be contained. Proper tube balancing and rotor speed limits are essential. Modern centrifuges include refrigeration, vacuum systems, and programmable controls. The development of safety interlocks and rotor lids has reduced accidents.3
Beyond routine lab use, centrifugation has niche applications. Analytical ultracentrifugation determines molecular weights and interactions without labeling. Zonal rotors allow large-scale purification of organelles. Centrifugal partition chromatography uses immiscible liquids for separation. In space, centrifuges simulate gravity for biological studies. The technique also aids in forensic analysis of soil and in the preparation of vaccines. The Svedberg unit, named after Theodor Svedberg, honors his pioneering work.4
This article focuses on the laboratory technique of centrifugation as used in research and clinical settings.
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