The last two decades have seen an explosive growth in the use of magnetic beads in Life Science, with sustained double figure sales increase all across the industry. The main driver of this success has been the use of magnetic beads as a solid phase on Chemiluminescence Immunoassays (CLIA) kits. Thanks to its easy automation, this technique has become the preferred choice for high throughput In Vitro Diagnostic.
Lluis M. Martínez, SEPMAG Chief Scientific Officer
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The binding specificity between antibody and antigen drive our immune systems to successfully fight infection. When a viruses or bacteria invade a body they are engulfed by macrophages, which break them down and present their epitopes to the B cells lymphocytes. These B cells read the epitope and create antibodies with an antigen binding site, or paratope, that specifically recognizes the invading pathogen, binds to it, and signals to the rest of the immune system that the pathogen/antigen should be destroyed. This antibody affinity to antigen is similar to the specificity of a key in a lock.
Magnetic properties of nanoparticles are used for drug delivery, therapeutic treatment, contrast agents for MRI imaging, bioseparation, and in-vitro diagnostics. These nanometer-sized particles are superparamagnetic, a property resulting from their tiny size—only a few nanometers—a fraction of the width of a human hair (nanoparticles are approximately 1/1,000 thinner than human hair). Superparamagnetic nanoparticles are not magnetic when located in a zero magnetic field, but they quickly become magnetized when an external magnetic field is applied. When returned to a zero magnetic field they quickly revert to a non-magnetized state. Superparamagnatism is one of the most important properties of nanoparticles used for biomagnetic separation.
Magnetic beads and separators have grown in popularity as a biotechnological tool over the past few decades. As we gained experience with the technology, we learned that all magnetic separators are not created equal. It turns out that it isn’t just the magnitude of the magnetic force that improves separation time, it is the way it spreads out over the working area that matters the most. A homogeneous magnetic separator is designed to ensure that every point within the working volume experiences the same magnetic force. This is especially important when scaling up a biomagnetic separation process from milliliters to liters.
The collection of tissue is a fundamental procedure for research and clinical biology. Before collection it is important to consider which method will be used to preserve the tissue and prepare it for histology or molecular analysis. There are two options to choose from when collecting and preserving tissue: frozen or formalin-fixed paraffin-embedded (ffpe). Each has its strengths and weaknesses, but these are only apparent when the intended use of the tissue is considered.
Anti human IgG is the most prevalent antibody isotype in human serum. It plays a critical role in the adaptive immune response. When a pathogen invades a human body it is intercepted by a white blood cell called a B-cell. These B-cell lymphocytes have cell surface receptors that bind a wide array of pathogens. Once activated, the B cell divides and produces offspring cells which secrete very specific antibodies capable of identifying that exact invading pathogen. These antibodies recognize a specific antigen binding site.
Protein A beads like ELISA, Immunoprecipitation, antibody purification, and multiplex assays require the attachment of specific antibodies to a solid support such as a column, polystyrene plate, agarose bead, or superparamagnetic nanoparticle. There are a number of ways that antibodies are attached to solid supports. Some of these include:
- covalently bonding the antibody’s primary amines directly to the surface
- biotin-streptavidin affinity linkages
- protein A and G
Magnetic bead separation is a quick, efficient, clean process that scientists use to replace filtration and centrifugation and separation techniques. Magnetic beads and particles are functionalized with antigens, antibodies,
catalyzers, proteins or nucleic acids, enabling action on cells, bacteria, viruses and other biological entities.
These complexes are then separated from a complex matrix with a magnetic separation rack. The result is an enriched and concentrated sample of the target entity.
The synthesis of complementary DNA (cDNA) is fundamental to the study of RNA expression in cells and tissues. RNA is fragile and not compatible with the polymerase chain reaction (PCR). Therefore, an intermediary step is needed to convert RNA to cDNA for analysis by quantitative PCR (qPCR). This qPCR technique utilizes specific primers and polymerase enzyme to amplify targeted sequences of cDNA. Since the cDNA is complementary to the initial mRNA isolate, this technique provides a quantitative readout of mRNA levels in the sample. The need for cDNA is so great that many companies sell cDNA synthesis kits to simplify the procedure.
We are all familiar with magnetic materials, but not so much with what exactly ‘magnetic’ means. The magnetic moment, usually quoted as ‘m’, it is defined as the property that makes a material align with an external magnetic field.
