What are Magnetic Beads?
Magnetic beads are nanoparticles that help to extract specific biomolecules. They have a core of iron oxide, covered with layers of different functional groups depending upon what to isolate. This provides the bead discrete binding properties and enables the purification of DNA, RNA, proteins, etc. in an easy, effective, and scalable way.
Why Use Magnetic Beads?
Nucleic acid extraction is the primary step for many downstream applications such as library preparation, microarrays, RT-PCR, etc. The demand for rapid and sensitive molecular diagnostics is rising. Especially seen during the COVID-19 pandemic with laboratories striving hard to develop methods to fight the virus. Used to 10-100 (at max.), research labs and institutions were prejudiced into running thousand of extractions every day. High-quality DNA samples with minimal contaminants and high integrity are vital for optimal sequencing performance.
Read more on the importance of high-quality DNA here.
Since the first DNA extraction by Friedrich Miescher in 1869, scientists have made tremendous progress in designing extraction methods that are more reliable, easier and faster to perform, more cost-effective and produce a higher yield. The liquid DNA extraction method involves the use of organic and inorganic reagents such as phenol-chloroform which are toxic to health. Spin columns provide a solid surface made of silica matrices (mostly). The DNA or RNA binds to the column while proteins and contaminants are discarded. This process demands several buffers, centrifuge machines, and much time to complete.
The need to increase the efficiency of DNA purification led to bead-based methods. The advances in nanotechnology over the past 20 years have made magnetic beads, a viable and attractive method for nucleic acid purification.
. Nucleic acids can be isolated from crude samples such as blood, saliva, swab, NP/OP swabs, tissue, plasma, serum, amniotic fluid, FFPE samples.
. Magnetic beads are non-porous and highly selective. As the sample does not enter the beads, there is minimal wastage.
. Magnetic beads have a large surface area. This gives them a high binding capacity.
. Magnetic bead-based workflow does not rely on costly lab equipment (like a centrifuge).
. Magnetic beads eliminate undue cell stress (as in the column-based method).
. Magnetic beads deliver a good quality DNA extraction with a high yield.
. As there’s low human interference, beads provide repeatable performance.
. Magnetic beads are safe to use, unlike phenol-based extraction which is a carcinogen.
How does Magnetic bead-based Separation Work?
Nucleic acid separation can be fickle. DNA is fragile; RNA even more so. The rise of nanotechnology in the past decade has set the stones for biomedical diagnostic devices. Novel methods to isolate nucleic acid have improved our ability to diagnose diseases.
As the beads bind to, let’s say, DNA, an external magnetic field makes them stick to the tube. The DNA is released as the elution buffer is added. The purified sample is now ready for quantitation and analysis.
Types of Magnetic Bead Surface Chemistries and Their Applications
| Type | Principle | Applications |
| Silica-based Magnetic Beads | Nucleic acids bind to the surface of silica-coated magnetic particles in a high concentration of salt and low pH solution. DNA and silica can move closer together in high salt solutions and attractive Van der Waals forces overcome repulsive electrostatic forces. Also, lowering the pH decreases the negative charge density on the surface of the silica, which may reduce the repulsive force between DNA and silica. Following magnetic separation, the nucleic acids are released under low ionic conditions. | • Nucleic acid extraction for molecular diagnostics applications such as qPCR |
| Carboxylated Magnetic Beads | In high concentrations of polyethylene glycol (PEG) and sodium chloride solutions, nucleic acids bind to the surface of carboxyl-coated magnetic particles. In the solution containing low concentrations of salt and PEG, DNA is at a random-coil state. The increasing concentration of PEG and sodium chloride promotes the condensation and compaction of DNA. The negative charge on the condensed part of DNA neutralizes in PEG solution with a small part of the negative charge remaining on the uncondensed part of DNA, eliminating electrostatic repulsion between nucleic acids and magnetic particles and promoting the DNA adsorption on the surface of magnetic particles. | • Purification of nucleic acids and proteins • Isolation of specific cell types • Immunoprecipitation of protein complexes • Affinity chromatography • Detection and quantification of biomolecules • Antibody purification • Bioprocessing and bioseparation • Gene expression analysis • Detection of pathogens • Synthesis of bioconjugates |
| Amine-based Magnetic Beads | Amine groups and imidazole molecules are sensitive to changes in pH. They have a surface charge of zero in neutral solution but are positive in acidic solution and negative in basic solution. The negatively charged nucleic acid adsorbs to the positively charged amine or imidazole moiety in an acidic solution. After magnetic separation, the DNA or RNA can be recovered by increasing the pH to make the solution more basic. | • Nucleic acid extraction • Plasmid DNA extraction • Protein Conjugations |
Some Promising Solutions by Magnetic Beads
Magnetic beads are used in various applications beyond healthcare. Some of the real-time practices are listed below:
- Applied Biocode: Barcoded magnetic beads are revolutionizing the battle against infectious diseases. Biocode uses magnetic particles in equipment and diagnostic techniques.
- Syngenta: Syngenta helps farmers around the world to grow nutritious and sustainable food. They use magnetic beads for DNA and RNA extractions from seeds and plants for their research.
- 23 and me: DNA plays a crucial role in health. 23 and me provides genetic insights in ancestry mapping. For this, they apply the DNA sample onto the chip with microscopic “beads”. Each bead is attached to a “probe,” a bit of DNA that matches one of the genetic variants. A fluorescent label identifies the genetic variant the DNA sample.
- Yescarta: Yescarta provides CAR-T cell therapies for the treatment of non-Hodgkin B-cell refracting or relapsing lymphoma. For this, they select T-cells with the use of magnetic beads.
Magnetic Beads by Cambrian Bioworks
We currently provide beads with a silica layer or carboxyl layer on the magnetite core. These have a wide range of applications from the purification of nucleic acids, immunoprecipitation of protein complexes, and gene expression analysis to detection and quantification of biomolecules.
The automation-ready kit comes with buffers and magnetic beads. The same kit can be run on a magnetic stand to perform extractions manually.
The kit ensures reproducible recovery of high-quality DNA from numerous sample types – whole blood, saliva, swabs, dried blood spots, cultured cells, tissue, and FFPE samples.
With our updated protocol we can now complete the whole process in less than 30 minutes!
Get an in-depth view of the performance data here: https://cambrianbioworks.com/dna-extraction-using-magnetic-beads/
Reach out to us to get complete protocols for gDNA extraction using magnetic beads.
To get a free sample contact us at support@cambrianbioworks.com or call us at +91 90356 74375.