Nucleic acid extractor

A nucleic acid extractor is a specialized instrument used for isolating and purifying nucleic acids (including DNA and RNA) from biological samples (such as blood, tissues, cells, saliva, etc.). The following is a detailed introduction:
I. Working Principle

1. Magnetic Bead Method
   • This is one of the most commonly used principles for nucleic acid extractors. In this method, a magnetic bead suspension is first added to the sample. The surface of the magnetic beads is usually coated with groups that can specifically bind to nucleic acids. After the sample is thoroughly mixed with the magnetic beads, the nucleic acids will bind to the magnetic beads. Then, through the action of an external magnetic field, the magnetic beads are separated from the solution. After multiple washings to remove impurities, the nucleic acids are eluted from the magnetic beads using an elution buffer, resulting in pure nucleic acids.
2. Centrifugal Column Method
   • After sample lysis, the lysate is added to the centrifugal column, which contains a special filter membrane. Under the action of centrifugal force, the nucleic acids will be adsorbed onto the filter membrane, while impurities are removed through the filter membrane. Then, further impurity removal is achieved through multiple washing and centrifugation operations. Finally, the nucleic acids are eluted from the filter membrane using an elution buffer to complete the nucleic acid extraction.

II. Instrument Structure

1. Mechanical Components
   • Sampling System: It is responsible for accurately adding samples and reagents (such as lysis buffer, washing buffer, elution buffer, etc.) to the reaction containers. This system usually includes high – precision pipettes or injection pumps to ensure the accuracy and repeatability of sampling and avoid nucleic acid extraction failure or poor quality due to sampling errors.
   • Mixing System: It is used to ensure thorough mixing of the sample with the reagents during sample processing. Common mixing methods include vortex mixing and oscillatory mixing, ensuring that the nucleic acids can fully bind to the magnetic beads (in the magnetic bead method) or be evenly distributed in reagents such as the lysis buffer (in the centrifugal column method and other methods).
   • Centrifugal System (if the Centrifugal Column Method is used): It provides centrifugal force to enable operations such as nucleic acid adsorption and impurity removal within the centrifugal column. The centrifugal system needs to have a stable rotation speed and precise control functions to ensure the effectiveness and efficiency of nucleic acid extraction.
2. Control Components
   • This is the “brain” of the nucleic acid extractor, including a microprocessor and operating software. Operators set extraction procedures through the operating software, such as sampling volume, mixing time and speed, centrifugal speed and time (if applicable), magnetic bead adsorption and elution time (for the magnetic bead method), and other parameters. The microprocessor precisely controls the operation of each component of the mechanical part according to the set procedures, ensuring that the entire nucleic acid extraction process proceeds in an orderly manner according to the predetermined steps.

III. Application Fields

1. Medical Diagnosis
   • In terms of infectious disease diagnosis, the nucleic acid extractor is crucial. For example, during the COVID – 19 pandemic, nucleic acid extraction from patient samples such as throat swabs and nasal swabs was a key step in detecting COVID – 19 infection. In addition, for the diagnosis of other infectious diseases such as influenza, hepatitis B, hepatitis C, and AIDS, the nucleic acid extractor is also used to extract viral nucleic acids from patient samples, providing pure nucleic acid samples for subsequent nucleic acid tests (such as PCR tests) to accurately determine whether a patient is infected with the disease.
   • In the diagnosis of genetic diseases, DNA is extracted from samples such as blood, amniotic fluid, and chorionic villi for genetic testing and analysis, helping doctors diagnose whether a fetus has a genetic disease or helping patients understand their own genetic status for early intervention and treatment.
2. Biological Research
   • In molecular biology research, the nucleic acid extractor is a commonly used piece of equipment in the laboratory. Researchers use it to extract nucleic acids from various biological samples for gene cloning, gene expression analysis, gene mutation detection, and other research. For example, when studying the mechanism of tumorigenesis, DNA and RNA need to be extracted from tumor tissues and normal tissues to analyze the differential expression and mutation of genes, thereby revealing the pathogenesis of tumors.
   • In genomics and transcriptomics research, a large number of samples need to undergo nucleic acid extraction. High – quality nucleic acid extractors can process samples quickly and efficiently, providing a guarantee for subsequent high – throughput sequencing and other research, helping researchers understand the gene composition and gene expression patterns of organisms.

IV. Advantages

1. Improved Extraction Efficiency
   • Compared with manual nucleic acid extraction, nucleic acid extractors can process multiple samples simultaneously. For example, some high – throughput nucleic acid extractors can process 96 or more samples at a time, saving a significant amount of time and labor. Moreover, the instrument has a high degree of standardization in operation, reducing the problem of unstable extraction results due to human operation differences.
2. Ensured Extraction Quality
   • Through precise control programs, nucleic acid extractors can ensure the stable quality of nucleic acids extracted each time. In all aspects such as sampling, mixing, washing, and elution, the instrument can operate according to the set parameters, avoiding problems such as inaccurate reagent addition, insufficient mixing, and incomplete washing that may occur in manual operations, thereby obtaining nucleic acid samples with high purity and good integrity, which is beneficial for subsequent testing and research.

V. Limitations

1. High Instrument Cost
   • The price of nucleic acid extractors themselves is relatively expensive, especially those with high – throughput and high – precision capabilities. For some small – scale laboratories or primary – level medical institutions, the procurement cost is a significant burden, limiting their popularity.
2. Requirements for Samples and Reagents
   • Different nucleic acid extractors may have specific requirements for sample types and reagents. If the properties of the sample do not meet the requirements of the instrument or incompatible reagents are used, the effect of nucleic acid extraction may be affected, and the instrument may even be damaged. For example, some magnetic bead – based extractors require that the viscosity of the sample not be too high, otherwise it will affect the binding and separation of magnetic beads and nucleic acids.