An Overview of The Different Types of Nucleic Acid Isolation

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February 3, 2023

Nucleic acid isolation is the process of separating DNA and/or RNA from proteins, membranes, and other cellular materials. Nucleic acids are large biomolecules vital to all forms of life, and they are the key components of many molecular testing methods we have today. They are composed of nucleotides, which are monomers made up of sugar, phosphate, and a nitrogenous base.

There are a variety of methods used to isolate nucleic acid from cellular material samples, which are typically divided into solution-based or column-based protocols. Most of these can be performed using nucleic acid separation products Tucker GA. This article will present the most widely used methods of nucleic acid isolation.

Magnetic Bead-Based Purification

Magnetic separation is a simple and effective method used in the isolation of nucleic acid. The beads used in this process have a negative surface charge which selectively binds to proteins. Another magnet is then used to aggregate the particles near the container wall. The rest of the sample, containing all the unwanted material is then drained away leaving behind the magnetic beads and nucleic acids which are then separated with a buffer.

Guanidinium Thiocyanate-Phenol-Chloroform Extraction

In this method, a mixture of phenol, chloroform, and a small amount of isoamyl is used to extract DNA from a sample. First, phenol and chloroform are added to the sample, forming an emulsion containing a layer of DNA at the top which is collected and precipitated by centrifugation. The DNA pellet is then dissolved with sterile water. RNA can be further separated from DNA using an acidic solution consisting of guanidinium thiocyanate, sodium acetate, phenol and chloroform.

Cesium Chloride / Ethidium Bromide Gradient Centrifugation

A method used in research labs since 1950, Cesium Chloride / Ethidium Bromide gradient centrifugation exploits the differing densities between the caesium ions and water, along with the intercalation of ethidium bromide to interfere with DNA replication, transcription, repair and recombination. It is more complicated, expensive, and time exhaustive than other isolation protocols, and requires a large amount of samples. This is why the isolation method is not used in clinical laboratories.

Solid-Phase Extraction

Solid-phase nucleic purification can be found in the majority of commercial extraction kits sold on the market today. This method uses a spin column operated under centrifugal force which separates DNA from the sample rapidly and efficiently. The column is first conditioned for sample absorption using a buffer at a certain pH. Once the cells have been disrupted with the centrifugal force, the desired nucleic acids get absorbed to the column wall due to the pH of the binding solution. Contaminants are washed away with a competitive agent and water is then used to release the nucleic acids from the column.


Since nucleic acid isolation is vital to the entire molecular process, the yield and purity of the nucleic acids are very important. Fortunately, many nucleic acid isolation techniques can be done using commercial kits that simplify the process and enable extracting pure nucleic acids.

If you’re looking for nucleic acid purification products in Tucker GA, AMD Biotech Inc offers a wide variety of nucleic acid isolation kits. Contact them to check out their inventory.

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