Automatic nucleic acid extraction kit

Ⅰ. Definition

An automatic nucleic acid extraction kit is a combination of matching reagents used for automatically extracting nucleic acids (including DNA and RNA) from biological samples (such as blood, tissues, cells, saliva, etc.). It is a tool used in conjunction with automatic nucleic acid extraction instruments during the nucleic acid extraction process and can separate and purify nucleic acids efficiently and accurately.

Ⅱ. Components

1. Lysis buffer
   • Its main function is to disrupt the cell structure in the sample to release nucleic acids. The lysis buffer usually contains surfactants, salts, and other components. For example, sodium dodecyl sulfate (SDS), as a common surfactant, can break the lipid bilayer of cell membranes and nuclear membranes, allowing the release of intracellular nucleic acids. The salt components help maintain the ionic strength of the solution, ensuring the smooth progress of the subsequent nucleic acid extraction process.
2. Binding buffer
   • After the nucleic acids are released from the cells, the binding buffer enables the nucleic acids to specifically bind to the solid – phase carriers (such as magnetic beads) in the extraction kit. The components of the binding buffer generally include chemicals that can interact with nucleic acids, which can promote the adsorption of nucleic acids onto the solid – phase carriers under specific conditions, preparing for subsequent separation and purification.
3. Washing buffer
   • It is used to wash the solid – phase carriers with bound nucleic acids to remove impurities. The washing buffer may contain appropriate amounts of alcohols (such as ethanol) and buffer systems. Alcohol substances can remove some water – soluble impurities, and the buffer system can maintain the stability of the pH value during the washing process, prevent the nucleic acids from detaching from the solid – phase carriers, and ensure the effective removal of impurities.
4. Elution buffer
   • Its function is to elute the purified nucleic acids from the solid – phase carriers. The elution buffer is usually a solution with an appropriate pH value and ionic strength. For example, the commonly used TE buffer (containing Tris – HCl and EDTA) can detach the nucleic acids from the solid – phase carriers without destroying the nucleic acid structure, obtaining a high – purity nucleic acid solution.
5. Solid – phase carriers (possibly)
   • In some automatic nucleic acid extraction kits, magnetic beads are used as solid – phase carriers. Magnetic beads are tiny magnetic particles, and their surfaces are usually modified to specifically bind to nucleic acids. During the automatic extraction process, the separation of magnetic beads from the solution can be conveniently achieved through the control of the magnetic field, thereby achieving the purpose of extracting and purifying nucleic acids.

Ⅲ. Working principle

1. Cell lysis
   • When a biological sample is added to the kit, first, under the action of the lysis buffer, the cells in the sample are lysed, the cell membranes and nuclear membranes rupture, and the nucleic acids are released into the solution. This process is the starting step of the entire nucleic acid extraction, ensuring that a sufficient amount of nucleic acids can be extracted subsequently.
2. Nucleic acid binding
   • The released nucleic acids specifically bind to the solid – phase carriers (if any) in the kit in the presence of the binding buffer. This binding is based on the interaction between the nucleic acids and the chemicals on the surface of the solid – phase carriers, enabling the nucleic acids to be “captured” onto the solid – phase carriers for separation from other impurities.
3. Impurity washing
   • The solid – phase carriers with bound nucleic acids come into contact with the washing buffer multiple times, and the impurities are removed under the cleaning action of the washing buffer. This step is crucial for ensuring the purity of the nucleic acids. Through repeated washing, impurities such as proteins, polysaccharides, and salts in the sample can be removed as much as possible.
4. Nucleic acid elution
   • The washed solid – phase carriers come into contact with the elution buffer, and under the action of the elution buffer, the nucleic acids detach from the solid – phase carriers and enter the elution buffer, thereby obtaining a purified nucleic acid solution, which can be used for subsequent molecular biology experiments, such as PCR, gene sequencing, etc.

Ⅳ. Application fields

1. Medical diagnosis
   • In clinical diagnosis, automatic nucleic acid extraction kits are commonly used for pathogen detection. For example, detecting the nucleic acids of viruses (such as hepatitis B virus, hepatitis C virus, HIV, etc.) in blood or detecting the DNA of bacteria in bacterial infections. In addition, in tumor diagnosis, it can be used to extract genetic information from tumor cells to assist in determining the type, stage, and treatment response of tumors.
2. Disease prevention and control
   • During an outbreak of an infectious disease, rapid and accurate nucleic acid extraction from a large number of samples from suspected cases is crucial. Automatic nucleic acid extraction kits can be used for large – scale screening of infectious diseases such as influenza and COVID – 19, helping public health departments timely grasp the epidemic situation and take effective prevention and control measures.
3. Biomedical research
   • In the field of gene research, whether studying the structure and function of genes or conducting gene expression analysis, high – quality nucleic acid extraction is required. This kit can provide researchers with standardized and efficient nucleic acid extraction methods, helping to study the mechanism of gene action in processes such as growth, development, and disease occurrence.
4. Forensic identification
   • Nucleic acids are extracted from biological samples (such as blood, hair, saliva, etc.) collected at crime scenes using automatic nucleic acid extraction kits, and then DNA analysis is performed, which can help identify criminal suspects and provide key evidence for case – solving.
5. Food safety testing
   • It is used to detect the nucleic acids of pathogenic microorganisms (such as Salmonella, Listeria, etc.) in food to ensure food safety and protect consumers’ health. It can also detect genetically modified components in food, providing technical support for food supervision.