1. Nucleic acid extraction
1.1 What is nucleic acid
Nucleic acid is divided into deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)，RNA can be divided into ribosomal RNA (rRNA), messenger RNA (mRNA), and transfer RNA (tRNA) according to their different functions.
1.2 Principles and requirements for nucleic acid extraction and purification
Ensure the integrity of the primary structure of nucleic acid; Excluding contamination from other molecules;
1.3. Common nucleic acid extraction methods
a. Solution extraction is a classic extraction method,Almost all contain detergents (such as SDS) and salts (such as Tris, EDTA, NaCl, etc.).The function of salt, in addition to providing a suitable lysis environment, also includes inhibiting the destruction of nucleic acid by nucleases in the sample during the lysis process (such as EDTA), maintaining the stability of nucleic acid structure (such as NaCl), etc.Decontaminants, on the other hand, denature proteins, disrupt membrane structures, and break down proteins that are linked to nucleic acids, thereby enabling nucleic acids to dissociate in the lysis system. Although this method has a lower cost, it is more cumbersome and the quality of extracted nucleic acids is also relatively average.
b. Column extraction
Column extraction is a relatively simple method used for the separation and purification of trace amounts of nucleic acids. Its basic principle is to use lysate to promote cell fragmentation and release nucleic acids from the cells. The released nucleic acid is specifically adsorbed onto a specific silicon carrier, which only has strong affinity and adsorption for nucleic acid, and does not adsorb other biochemical components such as proteins, polysaccharides, and lipids. Therefore, it is thrown out of the column during centrifugation.Wash the nucleic acid adsorbed on the specific carrier with eluent to obtain purified nucleic acid.Its cost is low, but the extraction quality is good, making it the mainstream extraction method in the current market.
c. Magnetic bead extraction
The principle of magnetic bead purification method is basically the same as that of silica gel membrane centrifugation column. By using nanotechnology to improve and modify the surface of superparamagnetic nanoparticles, superparamagnetic silica nano magnetic beads are prepared.This magnetic bead can specifically recognize and efficiently bind with nucleic acid molecules at the microscopic interface.By utilizing the superparamagnetism of silica nanoparticles, DNA and RNA can be isolated from samples such as blood, animal tissues, food, and pathogenic microorganisms under the action of Chaotic salts (guanidine hydrochloride, guanidine isothiocyanate, etc.) and an external magnetic field.