The four mainstream molecular diagnostic technologies

 Molecular diagnosis is a diagnostic technology that uses nucleic acid or protein as a biomarker for clinical detection. Molecular diagnosis technology provides information and decision-making basis for disease prediction, diagnosis, prevention, treatment and prognosis. In the face of a variety of sudden infectious diseases, rapid and accurate molecular diagnosis is the most economic and effective measures. The positive role of nucleic acid detection and other molecular diagnostic technologies in the COVID-19 fully confirmed this point.

In recent years, molecular diagnosis technology has developed rapidly. At present, it can be divided into four categories: molecular diagnosis technology based on nucleic acid molecular hybridization technology, molecular diagnosis technology based on PCR technology, molecular diagnosis technology based on gene chip technology and molecular diagnosis technology based on gene sequencing technology.

Nucleic acid molecular hybridization technology refers to two nucleic acid single strands from different sources, which specifically form double strands under certain conditions based on the principle of base complementary pairing, including Southern blot hybridization, Northern blot hybridization, in situ hybridization, and fluorescence in situ hybridization ( FISH) and other technologies. Among them, FISH uses fluorescently labeled probes to form hybrids with target fragments. The fluorescence detection system obtains relevant data of the DNA to be tested. It has the characteristics of strong specificity and fast detection speed, and is widely used in the field of prenatal diagnosis.

PCR technology, that is polymerase chain reaction, refers to the technique of amplifying target nucleic acid fragments in vitro. PCR technology mainly includes fluorescence real-time quantitative PCR and digital PCR. The operation process of fluorescent real-time quantitative PCR technology is carried out in a closed system, which can effectively reduce the probability of contamination, and can be used for quantitative detection by monitoring the fluorescent signal. It is the most widely used in clinical practice and has become the dominant technology in PCR. Digital PCR is also called single-molecule PCR,its principle is to place a single nucleic acid molecule in an independent reaction unit for PCR amplification, detect the fluorescence at the end of the reaction chamber and perform molecular counting statistics to achieve quantitative analysis. Because of its high sensitivity and high accuracy, it is not easily interfered by PCR reaction inhibitors, and it can achieve true absolute quantification without standard products, which has become a research hotspot.

The principle of gene chip technology is to fix a large number of nucleic acid probes of known sequence on the surface of the substrate, and then hybridize them with the target nucleotide, and obtain the sequence information of the sample to be tested by detecting the probe. Gene chips are classified into cDNA microarray chips and oligonucleotide microarray chips according to the types of probes. Gene chip technology has the characteristics of high degree of automation, simple operation, high throughput, etc., and is widely used in genotyping, gene expression, single nucleotide polymorphism detection, etc.

The four mainstream molecular diagnostic technologies are widely used in various clinical fields, providing scientific and effective detection data for disease prevention, diagnosis, and treatment.