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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.

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.

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

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.

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.

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.

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.

What is upstream and downstream processing?

Introduction to upstream and downstream processing. These terms are used more in the scientific industry, for example in pharmaceutical companies. Upstream is the first half of the process and everything associated with it. Downstream is the end of the biological process. Upstream processing being the first part of the biological process, it involves the growing of bacteria in media or culturing of cell lines. Companies use bacterial or human cells to harvest products of interest. There are many products that biological companies are interested in harvesting.