Laboratory centrifuges employ different separation methods.
Release time:
2016-11-24
Overview:
Laboratory centrifuge
Laboratory centrifuge As the name suggests, this is a small centrifuge specifically designed for experimental analysis—for example, separating a mixture of two proteins with different molecular weights. By adjusting the centrifuge to a specific rotational speed and allowing it to run for a certain period, the two proteins can be separated based on their differing masses. Centrifuges can be categorized by their intended use into industrial laboratory centrifuges and medical laboratory centrifuges. Industrial laboratory centrifuges are typically used for solid-liquid separation experiments in industrial settings, material performance analysis, small-scale separation processes, and enterprise laboratories. Medical laboratory centrifuges, on the other hand, are primarily employed in medical research, hospitals, pharmaceutical companies, biological research institutes, and fine chemical industries.
Laboratory centrifuges employ various separation methods, each suited to different applications. Currently, the two most commonly used centrifugation techniques are differential centrifugation and density-gradient centrifugation. In fact, these two centrifugation methods were briefly mentioned in the article “Preparation of Ultracentrifugation by Laboratory Centrifugation Techniques.” Today, we’ll provide additional explanations and a more comprehensive overview of the principles and applications of these two methods.
1. Differential Centrifugation: Many biologically active macromolecules and subcellular organelles are unstable and require low-temperature, high-speed centrifugation. The most commonly used method is differential centrifugation. After centrifugation, the supernatant and the pellet are separated; the supernatant obtained from this step is then subjected to further centrifugation at progressively higher speeds to isolate a second fraction of precipitate. This process is repeated, gradually increasing the centrifugal speed to sequentially separate the desired components. This method can effectively separate particles that differ significantly in size, but it cannot distinguish between particles of similar size. Moreover, the fractions obtained are often heterogeneous and may contain impurities or other types of particles.
2. Zonal Centrifugation: This method can be further divided into two types: rate-zonal centrifugation and isopycnic rate-zonal centrifugation.
1) Rate-zonal centrifugation: In this method, a small volume of suspension is placed on a gentle density gradient medium, which stabilizes the sedimentation of particles. Under centrifugal force, particles move away from their initial zone, and the speed of their movement depends on the size and shape of the particles as well as the forces they experience. Laboratory centrifuge is determined by centrifugal force. After a period of centrifugation, particles of different sizes will move according to their relative velocities and separate into distinct bands. Using this method, we can separate particles whose sedimentation velocity differences are 20% or greater.
2) Isopycnic Density Gradient Centrifugation: In this method, the suspension of particles to be separated is placed on top of a density gradient medium—or, more precisely, the particles are dissolved directly into the solution used to create the gradient. During centrifugation, the particles either float upward or sink downward until they reach a point in the gradient where their density matches that of the surrounding liquid. At this point, the particles become weightless and cease moving, regardless of how long the centrifugation continues. These particles form distinct bands, with each band corresponding to particles of a specific density. Thus, this technique relies on the principle of separating particles according to their buoyant densities. The media commonly used for this method include cesium chloride (CsCl) and cesium sulfate (Cs₂SO₄). The former is particularly suitable for DNA separation, while the latter is better suited for RNA separation. Compared to rate-zonal centrifugation, this method has one major drawback: during centrifugation, the particles are inevitably exposed to high concentrations of the gradient solution, which can cause partial damage to the particles and may result in the formation of additional bands that correspond to damaged particles.
Laboratory centrifuge As the name suggests, this is a piece of equipment specifically designed for laboratory use. It’s a specialized device that employs centrifugal force to rapidly separate mixed solutions—for example, biological cells, protein and other organic substances, inorganic solutions, and colloidal samples—enabling their separation, concentration, and extraction.
Laboratory centrifuges employ various separation methods, each suited to different applications. Currently, the two most commonly used centrifugation techniques are differential centrifugation and density-gradient centrifugation. In fact, these two centrifugation methods were briefly mentioned in the article “Preparation of Ultracentrifugation by Laboratory Centrifugation Techniques.” Today, we’ll provide additional explanations and a more comprehensive overview of the principles and applications of these two methods.
1. Differential Centrifugation: Many biologically active macromolecules and subcellular organelles are unstable and require low-temperature, high-speed centrifugation. The most commonly used method is differential centrifugation. After centrifugation, the supernatant and the pellet are separated; the supernatant obtained from this step is then subjected to further centrifugation at progressively higher speeds to isolate a second fraction of precipitate. This process is repeated, gradually increasing the centrifugal speed to sequentially separate the desired components. This method can effectively separate particles that differ significantly in size, but it cannot distinguish between particles of similar size. Moreover, the fractions obtained are often heterogeneous and may contain impurities or other types of particles.
2. Zonal Centrifugation: This method can be further divided into two types: rate-zonal centrifugation and isopycnic rate-zonal centrifugation.
1) Rate-zonal centrifugation: In this method, a small volume of suspension is placed on a gentle density gradient medium, which stabilizes the sedimentation of particles. Under centrifugal force, particles move away from their initial zone, and the speed of their movement depends on the size and shape of the particles as well as the forces they experience. Laboratory centrifuge is determined by centrifugal force. After a period of centrifugation, particles of different sizes will move according to their relative velocities and separate into distinct bands. Using this method, we can separate particles whose sedimentation velocity differences are 20% or greater.
2) Isopycnic Density Gradient Centrifugation: In this method, the suspension of particles to be separated is placed on top of a density gradient medium—or, more precisely, the particles are dissolved directly into the solution used to create the gradient. During centrifugation, the particles either float upward or sink downward until they reach a point in the gradient where their density matches that of the surrounding liquid. At this point, the particles become weightless and cease moving, regardless of how long the centrifugation continues. These particles form distinct bands, with each band corresponding to particles of a specific density. Thus, this technique relies on the principle of separating particles according to their buoyant densities. The media commonly used for this method include cesium chloride (CsCl) and cesium sulfate (Cs₂SO₄). The former is particularly suitable for DNA separation, while the latter is better suited for RNA separation. Compared to rate-zonal centrifugation, this method has one major drawback: during centrifugation, the particles are inevitably exposed to high concentrations of the gradient solution, which can cause partial damage to the particles and may result in the formation of additional bands that correspond to damaged particles.
Laboratory centrifuge As the name suggests, this is a piece of equipment specifically designed for laboratory use. It’s a specialized device that employs centrifugal force to rapidly separate mixed solutions—for example, biological cells, protein and other organic substances, inorganic solutions, and colloidal samples—enabling their separation, concentration, and extraction.
Address: No. 9, Lane 4390, Hulan Road, Shanghai
Website:www.lxylxj.com
Tel: +86-21-58116435
Fax: +86-21-51316027
Mobile: +8618801858806
E-mail: info@bioridgecentrifuge.com
Messages
Please leave your contact information, and we will get in touch with you as soon as possible.
Links: