Common classification and separation principle of magnetic beads
With the continuous development and improvement of extraction technology, magnetic bead extraction technology continues to rise in China. As the core material for extraction, magnetic beads are constantly being known. Magnetic beads are formed by covering a core of ferroferric oxide with a certain tissue, which can be adsorbed by magnets and at the same time have magical beads that can adsorb (bind) nucleic acids through surface coatings. The reason why he is said to be magical is that he is very useful! It can realize the automation and high throughput of nucleic acid extraction. So who are his family members? Next, I will share with you the common classification and separation principle of magnetic beads.
The main classification of magnetic beads
1. Silica gel magnetic beads
This is a type of nucleic acid-binding magnetic beads that appeared very early on the market, and it is also one of the widely used magnetic beads on the market. The reaction principle is that under the condition of high salt ion, nucleic acid and silica gel plasma membrane bind nucleic acid by positive and negative electric adsorption force, and then the nucleic acid is eluted and separated in the environment of low salt ion to achieve the purpose of nucleic acid extraction.
2. Amino magnetic beads
Amino magnetic beads are modified with amino groups on the basis of silica gel plasma membrane magnetic beads. By changing the pH of the solution, the combination and separation of nucleic acids and magnetic beads can be achieved. Of course, the pH value of this method is controlled. To meet the requirements, otherwise it will affect the nucleic acid binding and elution effect.
3. Hydroxyl magnetic beads
Hydroxyl magnetic beads are based on silica gel plasma membrane magnetic beads, with hydroxyl modification groups added, and the principle is similar to amino magnetic beads.
4. Aldehyde-based magnetic beads
After the silica gel plasma membrane magnetic beads are modified with the aldehyde group, the aldehyde group is combined with a specific primer to catch a specific nucleic acid. However, the cost of such magnetic beads is relatively high. The principle of the other aldehyde-based magnetic beads (no specific primer modification) is similar to the principle of the combination of amino and hydroxyl groups.
5. Cellulose coated magnetic beads
Cellulose-coated magnetic beads are another type of magnetic beads currently on the market. They are different from the silica-based plasma membrane series of magnetic beads. The cellulose membrane magnetic beads have a rougher surface and a larger relative surface area. The principle is to use the hydrophilicity of the cellulose membrane to combine with hydrophilic nucleic acids in a hydrophobic environment. This hydrophilic and hydrophobic binding force (covalent bond) is stronger than the positive and negative electric binding force (ionic bond).
The principle of magnetic bead separation of nucleic acids
The surface of nano-scale magnetic beads is modified with specific active functional groups that can adsorb nucleic acids. By using different lysis solutions, binding solutions, and washing solutions, they can specifically bind to the target nucleic acid under specific conditions, while using magnetic beads Its own magnetism can easily realize directional movement and enrichment under the action of an external magnetic field, so as to achieve the purpose of separating nucleic acid and impurities, and then realize the separation and purification of target substances to obtain purified nucleic acid.