DNA extraction is a fundamental technique used in molecular biology to isolate DNA from various biological samples. The process involves separating DNA from other cellular components to obtain pure DNA for further analysis or experimentation. Several methods are available for DNA extraction based on your use case or research requirements, with the most common technique being the phenol-chloroform extraction method and the most automatable technique being paramagnetic bead-based extraction. Both RNA extraction and protein purification follow the same basic principles.

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Steps for DNA and RNA purification

The extraction, isolation, and purification of nucleic acids from different sample types typically includes these steps:

  • Homogenize and lyse sample—disrupt cell membranes and walls
  • Bind samples—attach nucleic acids to specific matrix
  • Wash—remove impurities
  • Elute—release purified product
Steps for nucleic acid extraction: lyse, bind, wash, elute

Nucleic acid extraction and isolation methods

Nucleic acid extraction and isolation starts with disrupting the cellular structures containing the genetic material—nuclei, ribosomes, bacteria, viruses; this is usually accomplished by adding a compatible detergent, mechanical disruption, and/or heat. Several methods for nucleic acid purification are available, and each method is based on a different biochemical principle. Selection of a method is based on the throughput required, equipment available in the lab, or the degree of purity required. See our collection of lab essentials for molecular biology research.

Featured instruments and kits

Magnetic Dynabeads

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Paramagnetic bead-based nucleic acid purification

Paramagnetic beads are added to the sample, and their surfaces attract nucleic acids to bind to the beads. Using a strong magnet, the beads are held in place while removing unwanted material. After washing, the genetic material is eluted from the beads in water or a low-salt buffer. Using Dynabeads magnetic beads, many separation applications can be achieved.

Magnetic bead isolation is now one of the most popular nucleic acid extraction methods due to its scalability and automation compatibility. MagMAX bead kits and KingFisher Sample Purification Systems are designed to work together to efficiently purify a variety of nucleic acids.

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Organic extraction and precipitation

Nucleic acid isolation by organic extraction involves the addition of phenol and guanidine isothiocyanate to separate the DNA, RNA, and proteins into different organic phases. Organic extraction is a low-cost method, and with advanced reagents such as TRIzol or phenol-chloroform, are straightforward processes requiring less lab equipment.

After lysis is performed and the solvents are added, the mixture then goes through a process of centrifugation to separate the aqueous phase (containing nucleic acids) from the organic phase (containing proteins and lipids).

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Silica-based nucleic acid isolation

Nucleic acids bind to silica (also known as glass fibers) under high-salt conditions and can be released under low-salt conditions. Silica-containing columns provide an easy way to bind, wash, and elute purified nucleic acids from multiple clarified cell lysates in parallel.

Invitrogen Purelink and GeneJET columns are designed to flow buffers through centrifugation, vacuum, or gravity. Most protocols use spin column technology to take advantage of readily available lab equipment. Spin plates provide a high-throughput format based on the same isolation principle.

KingFisher purification instruments

Automated isolation, extraction, and purification of DNA, RNA, proteins, and cells. Applied Biosystems MagMAX optimized kits and reagents provide easy-to-use protocols that remove manual steps and help save time.

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Plasmid DNA isolation and purification

Plasmid DNA isolation and purification is an essential technique in molecular biology research, enabling the isolation and purification of plasmid DNA from bacterial cells. Plasmids, small circular DNA molecules found in microorganisms, play a crucial role in various applications, including gene cloning, protein expression, and genetic engineering.

The quality and purity of the isolated plasmid DNA are critical for reliable and accurate downstream experiments. The purification process involves careful separation of the plasmid DNA from other cellular components such as proteins, RNA, and genomic DNA, helping ensure high-quality DNA for further analysis and manipulation.


KingFisher PlasmidPro Maxi Processor

Automate plasmid purification


Steps used to purify plasmid DNA

Traditional manual plasmid DNA purification workflows often include these important steps:

  1. Harvest Bacteria: 20–30 mins of centrifugation
  2. Resuspend for lysing and neutralization: 15–20 mins via manipulation at bench
  3. Clarify lysate: 5–10 mins using centrifuge, syringe or vacuum; “ER reduction”
  4. Bind then wash then elute precipitate: 45–60 mins using drip technique and/or centrifugation
  5. Resuspend in solution: 10 mins of manipulation at bench
Steps for plasmid DNA isolation

Methods for plasmid DNA purification

Automate plasmid purification with prefilled cartridge

The KingFisher PlasmidPro Maxi Processor leverages the same processes and chemistry as traditional spin column-based plasmid purification methods with the advantages of automation. With prefilled reagents in a single cartridge, it helps eliminate the need for setup, centrifugation, and pipetting, reducing errors in sample preparation. This fully automated system with its "press and go" design is the only one of its kind for maxi-scale plasmid DNA purification.

Automate miniprep plasmid purification with magnetic bead technology

Applied Biosystems MagMAX Pro HT NoSpin Plasmid Miniprep Kit enables fast, scalable, and easy-to-set-up purification of transfection-grade plasmid DNA. Novel magnetic bead technology helps eliminate the need for time-consuming centrifugation or vacuum filtration steps, and the kit does not require the use of ethanol, chaotropic salt, and organic solvents, making it an eco-friendly and sustainable choice.

Column-based plasmid purification kits

Thermo Fisher Scientific offers a wide range of plasmid DNA extraction products that are designed to isolate plasmid DNA at the purity and scale you need and to support column-based workflows. Choose the PureLink or GeneJet kits based on purity grade and culture volume. Use our selection tool to find the right plasmid purification kit for your research.

Explore plasmid DNA isolation

Plasmid DNA Isolation


Instruments, kits, and reagents for nucleic acid extraction and purification techniques

Our nucleic acid extraction instruments, kits and reagents are optimized to help provide maximum yield, purity, and integrity from virtually any sample type. Whether you need to extract and purify RNA, viral nucleic acid, DNA fragments, plasmid DNA, or genomic DNA, Thermo Fisher Scientific has a solution.

RNA extraction kits

Select RNA extraction kits based on your application, sample, or RNA type.

Genomic DNA extraction

Sensitive, scalable genomic DNA purification products help maximize your efficiency.

Plasmid DNA purification

Isolate, purify, and extract high-quality plasmid DNA for cloning or transfection.

Viral nucleic acid purification

Purify viral DNA and RNA with excellent reproducibility from a variety of sample types.

Automated nucleic acid purification

Efficiently perform DNA, RNA, viral nucleic acid, and plasmid isolation with MagMAX kits and KingFisher automated nucleic acid purification systems.

PCR & agarose gel cleanup

Purify DNA fragments with simple, rapid PCR and gel cleanup kits.

DNA analysis

Different DNA analysis methods allow researchers to gain insights into genetic variations, gene expression, specific DNA sequences, and aspects of DNA structure and function. Commonly used DNA analysis methods include the following:

Disrupt cells or tissues to allow extraction of DNA, RNA, and proteins. Our product range includes rotor-stator, ultrasonic, and bead-based homogenisers.

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For Research Use Only. Not for use in diagnostic procedures.

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