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Lluis M. Martínez, SEPMAG Chief Scientific Officer

Lluis M. Martínez, SEPMAG Chief Scientific Officer
Founder of SEPMAG, Lluis holds a PhD in Magnetic Materials by the UAB. He has conducted research at German and Spanish academic institutions. Having worked in companies in Ireland, USA and Spain, he has more than 20 years of experience applying magnetic materials and sensors to industrial products and processes. He has filed several international patents on the field and co-authored more than 20 scientific papers, most of them on the subject of magnetic particle movement.

Recent Posts

 

Nucleic Acid Isolation

Our understanding of genetic material has substantially increased since Friederich Miescher first extracted DNA in 1869. He discovered that a material exists within cells that precipitates out of acidic solution and dissolves into alkaline solution. He called it nuclein because it seemed to be located within the nucleus. It took until 1953 for the structure of DNA to be elucidated. It was during this time that procedures to isolate DNA began to emerge. Later, during the 1960's and 70's scientists were furiously untangling the cellular environment, and the discovery of RNA with its various forms and functions further refined DNA purification procedures.

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Cell sorting techniques

Isolating cell populations is required for many fields of research, such as cell function, signaling and gene expression. Techniques that enable the rapid and accurate enrichment of target cell populations are therefore an area of substantial interest.

Cell sorting techniques fall into two general categories: bulk sorting and single cell sorting. In single cell sorting each cell is analyzed individually, whereas in bulk cell sorting all of the target cells are collected together.

While cell sorting is highly accurate, a sorted cell population is not “pure”. Instead, the collected population is referred to as “enriched”. Compared to bulk sorting, single cell sorting results in more homogeneous and highly enriched cell populations.

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Hot gravity filtration and vacuum filtration in recrystallization

Recrystallization is the process of obtaining pure crystals from a compound containing impurities in a solvent. Hot gravity filtration is a process commonly used to remove these impurities from a solution prior to recrystallization. 

Hot filtration is a type of filtration where the filtration equipment and the sample are heated during the process. Hot filtration is needed for recrystallization when impurities exist in solution. Recrystallization requires a hot solution because the solution needs to be supersaturated for crystals to form on cooling. Hot solutions can hold more solute in suspension compared to a cold solution because the solubility of most solids increases with a rise in temperature. This means that a saturated solution will contain more dissolved solute if prepared at a higher temperature than at a cold temperature. When the hot solution then cools, it will be supersaturated – it will hold more dissolved solute than its cold equivalent would. 

The impurity may have a different solubility than the compound in certain solvents. The aim is to choose a solvent that dissolves the compound when heated, but that doesn’t dissolve the impurity at high temperatures. The impurity is then filtered out during the hot gravity filtration process.

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Nanobeads in biotechnology

Nanobeads have applications ranging from basic science research to clinical imaging and targeted drug delivery. Nanobeads are composites of nanoparticles. Nanoparticles are defined as being less than 100 nanometers in diameter, while nanobeads are usually around 50 to 200 nanometers in diameter. There are also microbeads, but these are much larger and have diameters of at least 1000 nanometers, or 1 micrometer, which is close to the size of a cell. Bacterial cell diameters range from 0.5 to 2 micrometers in diameter, and animal cells range from 10 to 30 micrometers in diameter. The size of nanobeads is very important to their function; partly because they are so much smaller than a cell, which enables them to be used for cell labeling and isolation. In the case of magnetic nanobeads, the nanometer size imparts the paramagnetic property that is so valuable for biomagnetic separation, clinical imaging (contrast enhanced magnetic resonance (MRI)), and therapeutics such as magnetic hyperthermia for targeted tumor destruction.

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Protein A Beads Optimization

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
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Agarose Resin Chromatography

Introduction to Chemiluminescence immunoassays

Using Agarose Resin chromatography allows for a versatile, prepacked column that enables small-scale, high-resolution size exclusion chromatography for preparation, characterization, and analysis of proteins and other biomolecules. Size exclusion chromatography, also known as gel filtration, is a common technique used to separate compounds of small molecules, such as proteins, polysaccharides, and nucleic acids when in an aqueous solution. This can be extremely useful in numerous commercial applications, such as analysis and determination of an unknown sample, removal of large proteins for purification of a sample, for removing small molecules such as dyes and primers, and buffer exchanges. Such chromatography is purchased as a prepacked column that allows for increased resolution and analysis, quick runtime, with a high pH tolerance to allow applications to a variety of molecules and substances. One example of a commercially available separation is Superose 6 chromatography, found here.

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Magnetophoretic characterization of anisometric magnetic nanoparticles for hyperthermia

Introduction to Chemiluminescence immunoassays

One of the most promising applications of magnetic nanoparticles in medicine is their use for killing cancer cells by hyperthermia. You can place the nanoparticles in the right place by functionalizing them with antibodies specific to the membranes of the cancer cells and/or applying a magnetic field gradient to focalize them in a predetermined region of the body. If you apply an alternate magnetic field, the nanoparticles will heat and, they will kill the cells they are attached to. With the appropriate intensity and frequency, the increase in temperature will just be a few degrees and the effect would be very localized and selective.

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Chemiluminescent serological tests

Introduction to Chemiluminescence immunoassays

Serological tests are used to gain a deeper understanding of the immune response to pathogens and the tests help maintain community health by checking for antibodies in human biological samples. Chemiluminescence is a widely used system of reporting binding events. It is preferred because it uses a simple device for measurement, often one that measures output of visible light. This also allows the process to have a wide dynamic range, detecting light from binding events whether the sample is dilute or concentrated. Such detection is done with high sensitivity and with low background noise. The chemiluminescent magnetic microparticle immunoassay (CMIA) is a method developed to bring together the advantages of chemiluminescence and magnetic particles for immunoassays.

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Magnetic beads vs Agarose beads: Advantages of Magnetic Agarose in Protein Purification

Most current protein purification methods use agarose beads carrying affinity functionalities such as IMAC, Glutathione, or antibodies. The choice of these functional groups depends on the protein of interest to be purified, and a large variety is available, including pre-functionalized beads that can be coupled to biomolecules (see SEPMAG® protein purification handbook chapter 4 and 5).

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A general filtration process

Filtration is a simple technique used to separate solid particles from suspension in a liquid solution. There are many filtration methods available, but all are based on the same general principle: a heterogenous mixture is poured over a filter membrane. The filter membrane has pores of a particular size. Particles larger than the pores will be unable to pass through the membrane, while particles smaller than the pores will pass through unhindered. Additionally, all liquids will pass through. The final result of a filtration process is a collection of residue on the filtration membrane. This residue is therefore effectively separated from the rest of the mixture that passed through the membrane.

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