The Best DNA Extraction Methods from Saliva or Buccal Swabs

1. Precipitation-Based Chemistry: Effective & Fully Optimised

The simplest DNA extraction method offered by Isohelix, precipitation-based chemistry is included in the BuccalFix Plus (BFP), BuccalPrep Plus (BPP) and SalivaPrep-2 (GSPN) kits.

In the first DNA extraction step, buffers in the kits lyse cells in the samples, and then nucleic acids are purified via precipitation, leaving contaminants behind. Proteinase K is added during the protocol to increase purity by digesting contaminating proteins.

Precipitation methods enable the rapid and efficient extraction of high yields of high molecular weight DNA and can be easily scaled to accommodate different sample volumes. As these kits don’t require additional solvents, columns, or filtration, workflows are easy to automate, with fast handling times and reduced sample steps. The unique precipitation chemistry maximises recovery of high molecular weight DNA, while minimising co-precipitation of RNA and degraded low-weight DNA.  

• Benefits: User-friendly, fast protocol, easy to automate, high molecular weight DNA, scalable, no additional solvents needed.
• Applications: PCR/qPCR, Microarray, Methylation Array, Sanger Sequencing, Next-Generation Sequencing (NGS).

2. Silica Spin-Columns: Familiar method, reliable results

Silica membrane-based spin columns, such as those included in the Xtreme (XME) and Xtreme-RNA (XMR) kits, are a tried and tested extraction method, allowing the purification of very high-purity, high molecular weight DNA or RNA that can be used in demanding downstream applications such as next generation sequencing or microarrays.

Cells are lysed to release nucleic acids, and then samples are centrifuged to filter them through a silica membrane inside the column. Under the right ionic conditions, nucleic acids selectively bind to the silica membrane, and unwanted proteins and inhibitors are then washed away. Finally, the ionic conditions are altered to elute nucleic acids from the column in an aqueous solution.

Using a silica column maintains the integrity of your nucleic acids while ensuring the removal of traces of PCR inhibitors. Isohelix spin column-based kits can be used to process large numbers of samples and are available in manual or high-throughput formats.

• Benefits: Very high purity DNA or RNA
• Applications: PCR/qPCR, Microarray, Methylation Array, Sanger Sequencing, NGS.

3. Magnetic Beads: High-Throughput Solutions

Magnetic-bead-based methods such as Buccal-Mag (BMG) and Saliva-Mag (GSM) can be used to produce high yields and purities, are fast and reliable for medium to high throughput applications, and extraction is performed in the original sample collection tube, reducing waste and cost. Buccal-Mag kits include magnetic beads with high nucleic acid binding capacities with a large surface area for fast attachment, enabling rapid extraction of intact genomic DNA using a bind/wash/elute workflow.

Magnetic separator racks are available for medium-throughput sample processing, (MR-24) or for high-throughput automated processing mag-bead-based kits can be used with most openly programmable automated DNA extraction and liquid handling systems fitted with magnetic racks and heat blocks.            

• Benefits: Designed for high throughput & automated applications.
• Applications: PCR/qPCR, Microarray, Methylation Array, Sanger Sequencing, NGS.

4. Direct to PCR: Fast PCR-Ready DNA

Direct-to-PCR kits such as the Salivalyse (SEK) and Buccalyse (BEK) allow users to rapidly prepare DNA from saliva and buccal swabs ready for amplification-based analysis methods. This method bypasses the need for time-consuming DNA extraction and purification steps, thus reducing the overall time and effort required for DNA analysis. These kits are ideal for high throughput and automated workflows, and also reduce consumable waste.

• Benefits: Rapid workflow, easy to automate, reduced waste
• Applications: PCR, qPCR, Loop-Mediated Isothermal Amplification (LAMP)