DNA purification is an essential step in many molecular assays such as PCR or qPCR, as well as DNA sequencing. It eliminates contaminants such as salts, proteins and other impurities that can disrupt downstream processes. It also ensures the desired DNA is clean and is present so that it can be used for further analyses. The quality of DNA is assessed by spectrophotometry (the ratio of A260 to A280) and gel electrophoresis and other methods.
The first step of a DNA purification procedure is cell lysis. In this process, the cellular structure is disrupted by reagents or detergents such as SDS to release DNA. To further purify DNA, protein-denatured reagents such as sodium dodecylsulfate as well as Ethylene diamine tetraacetic acids (EDTA) are added to break down the proteins. They are then removed from the nucleic acids solution through centrifugation and wash steps. If there is RNA present in the sample the ribonuclease process can be added to further denature RNA. The nucleic acid is diluted using ice-cold alcohol to make it distinct from other contaminants.
Ethanol is a solvent that can be used to remove salts and other contaminants from nucleic acids samples. Researchers can evaluate the results of different tests using an ethanol concentration that is standard, which is an excellent choice for workflows that require high-throughput. Other solvents, such as chloroform and phenol could be utilized, but they are more toxic and require additional steps to avoid cross-contamination with other cellular debris or proteins. Newer methods can make it easier to complete the DNA purification process by using ethanol with low-ionic strength, which has been shown to be as efficient as conventional organic solvents in purifying DNA [26]. This is especially the case when paired with a spin column-based DNA extraction kit.
http://www.mpsciences.com/2021/04/15/gene-synthesis-and-transcription-processes/