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DNA & RNA Purification

Structure of DNA – various methods are used for DNA purification

Extraction of DNA and RNA is a basic method used in molecular biology. The need for high-quality, highly pure nucleic acid is important for a wide range of research and clinical applications. Nucleic acid purification is an initial step in many molecular biology and genomic workflows.

DNA and RNA samples are often obtained from crude preparations. Genomic DNA, plasmid DNA, and total RNA can be extracted and purified from a variety of sources including bacterial and mammalian cells, plant tissue, fungal tissue, mammalian tissue, blood, plasma, serum, viruses, buccal and nasal swabs, gel matrices, PCRs, and other enzymatic reactions. Isolation of nucleic acid from these samples often involves the lysis of cell membranes or sample homogenization, followed by the removal of proteins, enzymes, detergents, salts, and lipids.

Common approaches include:

  • Alkaline extraction
  • Phenol-chloroform extraction
  • Cesium chloride (CsCl) density gradient centrifugation
  • Oligo(dT)-cellulose chromatography
  • Silica matrice
  • Glass beads
  • Diatomaceous earth
  • Anion exchange chromatography
  • Size exclusion chromatography


The final application will dictate the best method for purification. Downstream applications include PCR, qPCR, restriction digests, ligation, cloning, genotyping, gene expression analysis, next generation sequencing (NGS), and Northern and Southern blotting.


Related Technical Articles

  • Impact of Purification Method on Accuracy of DNA Quantitation and Downstream Enzymatic Processes. Evaluation of the purity of genomic DNA by UV spectrophotometry, gel electrophoresis, and downstream qPCR using GenElute™-E DNA purification kits.
  • An overview of methods for quantifying DNA and RNA, how to measure DNA and RNA concentration and yield, and how to assess purity of nucleic acid samples.
  • The availability of simple methods for purification of DNA and RNA has greatly facilitated the analysis and characterization of the genome and gene expression. There is a demand to isolate DNA and RNA rapidly and conveniently from a variety of cellular sources, including cells and tissues from mammalian, plant and bacterial cultures.
  • Two separate studies were conducted to analyze long-term storage of blood in DNAgard Blood stabilization reagent.
  • Affinity chromatography is the process of bioselective adsorption and subsequent recovery of a compound from an immobilized ligand. This process allows for the highly specific and efficient purification of many diverse proteins and other compounds. The process requires the utilization of an appropriately selective ligand which will bind the desired compound generally with a dissociation constant in the range of 10-4 to 10-8, while permitting recovery under mild conditions. The ligand is generally immobilized on a beaded and porous matrix which may be in the form of a column packing or batchwise adsorption medium.
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