Material And Use Of Centrifuge Tube
The aim of centrifugal technology is to separate and prepare different biological samples. Under high-speed rotation, place the biological sample suspension in a centrifuge tube. The suspended tiny particles settle at a certain speed so as to be separated from the solution, due to the huge centrifugal force. The centrifuge tube is one of the most commonly used experimental consumables in centrifugation experiments.
Principle of centrifuge tube
When a particle (biomacromolecule or organelle) is subjected to centrifugal force under high-speed rotation, this centrifugal force “F” is defined by the following formula, namely: F = ma = mω2 r a — acceleration of particle rotation, m — the effective mass of the settled particle, ω—the angular velocity of particle rotation, r—the radius of rotation of the particle (cm). Centrifugal force is usually expressed in multiples of Earth’s gravitational force, so it is called the relative centrifugal force “RCF”. Or multiply the number by “g” to express for example 25000×g, which means the relative centrifugal force is 25000.
What material is centrifuge tube?
1. Plastic centrifuge tube
It’s made of plastic, with a transparent or translucent appearance, and small hardness. With the puncture method, the gradient can be taken out. But compared with glass and stainless steel, it is easy to deform and cannot resist organic solvents. Sample leakage is the most important factor to consider when choosing the tube. For the plastic centrifuge tube, there is a cap to prevent sample volatilization. When choosing a plastic centrifuge tube, we should also pay attention to check whether the tube cover is tight and whether it can be tightly covered during the test, so as to achieve the inversion without leakage; we all know that in plastic centrifuge tubes, the commonly used materials are PE, PC, PP, etc. Among them, the performance of polypropylene PP tubes will be relatively good, so we should consider polypropylene plastic centrifuge tubes as much as possible when selecting plastic centrifuge tubes.
2. Glass centrifuge tube
As we’ve mentioned, the glass centrifuge tube has longer service life and can resist organic solvents. But when using glass tubes, the centrifugal force should not be too large, and rubber pads are required to prevent the tubes from breaking. Also, it is not suitable for high-speed centrifuges. The cap of the centrifuge tube is not closed well enough, and the liquid cannot be filled (for the high-speed centrifuge and the use of an angle rotor) to prevent overflow and loss of balance. If spillage occurs, the centrifugal chamber and rotor will be contaminated and the inductor performance will also be affected. The liquid must be filled in the centrifuge tube, during ultracentrifugation, due to the high vacuum required.
3. Steel centrifuge tube
The steel centrifuge tube has high strength, no deformation, and can resist heat, frost, and chemical corrosion. Try to avoid corrosion from these chemicals.
Ultrafiltration centrifuge tube usage and precautions
What is the use of centrifuge?
1. Choose a suitable ultrafiltration centrifuge tube, mainly considering MWCO and concentration volume. Generally, the molecular weight cutoff should not be greater than 1/3 of the molecular weight of the target protein. For example, if the molecular weight of the target protein is 35kDa, you can choose a 10kDa molecular weight cutoff ultrafiltration centrifuge tube. . If the molecular weight of the target protein is about 10kD, an ultrafiltration centrifuge tube with a molecular weight cutoff of 3kD can be used.
3. The newly purchased ultrafiltration is dry, add MilliQ water before use, the water volume is completely passed through the membrane, and it is pre-cooled in an ice bath or refrigerator for a few minutes. Get the water out and the protein solution is added. The amount added is subject to the white line at the top of the tube. The operation should be light. Precool the ultrafiltration centrifuge tube on ice before the protein solution is added.
4. Both mass and center of gravity must be balanced. Note that the rotation speed and acceleration should not be too fast, otherwise the ultrafiltration membrane will be damaged directly. Start centrifugal ultrafiltration (centrifuge pre-cooled to 4 degrees). After converting the rpm of different centrifuges into g, there are differences. The acceleration of the centrifuge is set to a low gear to reduce the pressure on the membrane. Please take note that before leaving the centrifuge, the centrifuge must reach the target speed. Otherwise, when there is a problem with the centrifuge, it cannot be dealt with in time, and the consequences are unpredictable!
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