The application of liquid biopsy technology in prenatal screening and tumor detection is becoming increasingly widespread, and sample quality is the basis for determining the accuracy of test results. The content of free DNA in blood is extremely low and easily degraded. How to stably preserve these trace nucleic acids has become a practical problem in clinical testing. Free DNA preservation solution is a professional solution developed to meet this demand, ensuring the integrity of samples from collection to testing by inhibiting nucleases, protecting white blood cells, and preventing red blood cell rupture.
Appearance and Sterility Requirements
The free DNA preservation solution first needs to meet the basic quality indicators. The appearance of the product should be a colorless, clear and transparent solution, and the contents can be clearly observed during visual inspection without the presence of foreign impurities. This requirement not only reflects the standardization of the production process, but also facilitates users to quickly determine whether the preservation solution is in a normal state before operation. Sterility is another basic requirement, and the preservation solution undergoes sterilization treatment during the production process to ensure that no exogenous microbial contamination is introduced into the blood sample.
The core function of stabilizing free DNA
The primary task of the preservation solution is to stabilize free DNA in the blood. After the collection of blood samples, the free DNA originally present in the plasma faces multiple threats, among which the most important is the degradation effect of nucleases. Nucleic acid enzymes are widely present in blood components and can break down free DNA into small fragments, leading to a decrease in the concentration of the target test substance. Nucleic acid enzyme inhibitors are added to the free DNA preservation solution, which can take effect at the moment of blood collection, inhibiting the activity of nucleic acid enzymes and protecting free DNA from degradation. Within the temperature range of 4 to 37 degrees Celsius, blood samples treated with preservation solution can be stably stored for up to 14 days, providing ample time window for sample transportation and testing arrangements.
Avoid contamination of the somatic genome
The core requirement of free DNA testing is that the measured DNA molecules are derived from free fragments in plasma, rather than genomic DNA released after blood cell rupture. White blood cells contain a large amount of genomic DNA inside. Once white blood cells rupture, these high molecular weight DNA will be released into the plasma, significantly altering the composition and concentration of free DNA and seriously interfering with the authenticity of detection results.
The second core function of free DNA preservation solution is to protect the integrity of white blood cells. By maintaining the stability of the cell membrane and a suitable osmotic pressure environment, the preservation solution prevents the rupture of white blood cells during storage and transportation, thereby avoiding the release of genomic DNA from white blood cells into the plasma. This allows the concentration of free DNA in the plasma to remain constant, accurately reflecting the original state at the time of collection.
Effectively prevent hemolysis
The rupture of red blood cells can lead to hemolysis, and the released hemoglobin not only makes the plasma appear red, but also releases various enzymes and nucleic acid substances inside the red blood cells, which interfere with free DNA detection. The third function of free DNA preservation solution is to protect red blood cells from rupture and prevent hemolysis. This function also relies on the protective effect of the preservation solution on the cell membrane and precise regulation of osmotic pressure.
Application scenarios and advantages
Free DNA preservation solution is widely used in prenatal screening and tumor detection projects. In prenatal screening, non-invasive prenatal testing is performed by detecting fetal free DNA in the plasma of pregnant women; In tumor detection, early screening and treatment monitoring are carried out by detecting circulating tumor DNA in the patient's plasma. Compared to ordinary blood preservation solutions, free DNA preservation solutions solve the problem of timely processing of samples, greatly simplifying storage and transportation conditions, allowing samples to be stored stably over a wide temperature range, reducing logistics difficulties and testing costs. The shelf life of the storage solution is one year, which facilitates inventory management in the laboratory.
