ultracentrifuger

Ultracentrifuger are high-speed centrifuges designed to sediment subcellular components, macromolecules, and particles that are not separable at conventional speeds. By generating centrifugal forces typically in excess of 100,000 x g, they enable discrimination by size, density, and shape. They are used in biochemistry, molecular biology, and clinical research to purify proteins, nucleic acids, organelles, viruses, and lipoproteins, and to analyze molecular interactions.

Most ultracentrifuges use fixed-angle or swinging-bucket rotors. In fixed-angle rotors, samples in tubes remain at a fixed angle during spinning, whereas swinging-bucket rotors allow tubes to move to a horizontal position under rotation, which can improve gradient formation. They are often refrigerated to protect heat-labile samples and to maintain stable density gradients.

Preparative ultracentrifugation isolates macromolecules and particles, sometimes using gradient media such as sucrose or cesium chloride that create a density gradient during centrifugation. Analytical ultracentrifugation determines properties such as sedimentation coefficient and molecular weight by observing sample behavior during rotation.

History: ultracentrifuges were developed in the early 20th century by Theodor Svedberg, whose work on disperse systems and ultracentrifugation earned a Nobel Prize in Chemistry in 1926.

Safety and maintenance: rotor integrity, proper balancing, and adherence to manufacturer limits are critical due to high rotational forces; regular maintenance and calibration are required.

Common fields include virology, protein purification, lipid research, and extracellular vesicle research.