Ultracentrifugation Protocol
Ultracentrifugation Protocol - Related Videos
08:42
Density Gradient Ultracentrifugation
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2023
Density gradient ultracentrifugation is a common technique used to isolate and purify biomolecules and cell structures. This technique exploits the fact that, in suspension, particles that are more dense than the solvent will sediment, while those that are less dense will float. A high-speed ultracentrifuge is used to accelerate this process in order to separate biomolecules within a density gradient, which can be established by layering liquids of decreasing density in a centrifuge tube. The...
03:04
Ultracentrifugation-Based Isolation of Legionella pneumophila Outer Membrane Vesicles
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2026
Source: Jung, A. L., et al. Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages. J. Vis. Exp. (2017)This video demonstrates the isolation of outer membrane vesicles (OMVs) from Legionella pneumophila using sequential centrifugation, sterile filtration, and ultracentrifugation. The purified OMVs, enriched in membrane proteins and lipopolysaccharides, are suitable for host-pathogen interaction studies.
11:36
Assembly, Loading, and Alignment of an Analytical Ultracentrifuge Sample Cell
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Cited by 21 •
2009
The analytical ultracentrifuge (AUC) sample cell holds sample and reference buffer and during experiments and is exposed to high vacuum and rotor speeds up to 60,000 rpm. This video will demonstrate the rigorous attention to detail necessary for assembly, loading and alignment of this very important component of an AUC experiment.
06:47
Isolation and Analysis of Plasma Lipoproteins by Ultracentrifugation
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Cited by 9 •
2021
Several methods have been used for analyzing plasma lipoproteins; however, ultracentrifugation is still one of the most popular and reliable methods. Here, we describe a method regarding how to isolate lipoproteins from plasma using sequential density ultracentrifugation and how to analyze the apolipoproteins for both diagnostic and research purposes.
04:27
Purification of Subpopulations of Extracellular Vesicles: A Technique to Purify Subpopulations of Extracellular Vesicles Using Density Gradient Ultracentrifugation
0 Views •
2023
This video demonstrates the density gradient ultracentrifugation-based purification method to isolate subpopulations of extracellular vesicles suitable for characterization studies.
FAQs
Particles move through the liquid at different rates because centrifugal force interacts with their size, density, and shape. These properties determine how quickly each component travels during a spin, so particles that differ in physical characteristics can become separated. This principle lets investigators distinguish biological structures within complex samples rather than treating the sample as a single population.
An Ultracentrifugation Protocol using differential centrifugation separates material through successive spins, with each stage providing a further fractionation step. Density-gradient centrifugation uses a prepared gradient and resolves components according to where they migrate relative to their buoyant density. The first approach supports staged separation, whereas the second provides position-based resolution within the gradient.
Rotor speed and spin time determine how much separation occurs, while temperature control helps protect sample integrity during processing. Changing these settings can alter the movement of biological particles through the medium and therefore the reproducibility of fractions. A protocol should keep these parameters controlled and documented when comparing samples or repeating an experiment.
Gradient composition is a central variable in density-gradient work because it establishes the medium through which particles migrate and affects the positions at which components resolve. Matching the gradient to the intended separation allows particles to be distinguished by buoyant density. Inconsistent composition can reduce reproducibility, making comparisons between preparations more difficult.
Begin by selecting either successive spins or a density gradient according to the desired separation, then define the liquid medium and, when applicable, gradient composition. Set rotor speed, duration, and temperature before processing, and maintain those conditions consistently. This workflow creates a reproducible basis for fractionating cells, organelles, macromolecules, or particles.
Use differential centrifugation when the goal is staged fractionation through successive spins, such as separating cellular material into progressively distinct fractions. Choose density-gradient centrifugation when the experiment requires components to resolve at positions associated with buoyant density. The choice therefore depends on whether the protocol emphasizes sequential separation or density-based resolution.
In biology, the method supports cell fractionation, purification of proteins and nucleic acids, and isolation of extracellular vesicles. It can also be applied to particles such as viruses. The resulting separation is useful for analyzing cells, organelles, macromolecules, and other biological particles, provided speed, time, temperature, and gradient conditions are controlled.