The search for alternatives to chromatographic resins is not new. With the continuous increase in expression levels in recombinant protein purification, columns are struggling with crude lysates. The need to clarify suspensions containing high levels of expressed protein for post-purification re-concentration no longer appears to be the most efficient strategy. You will find much more information about this topic in our protein purification handbook.
Nanoparticles incorporating different functions are useful and necessary products for assays, drug delivery, and other life science applications. For example, magnetic nanoparticles can be used as contrast agents for magnetic resonance imaging (MRI), to dissipate energy under an oscillating field to locally raise temperature (hyperthermia), or to improve manufacturing of complex nanoparticles via use of magnetic separation. One or more different antibodies and/or fluorescence, luminescence agents as well as other functionalities such as catalytic or enzymatic groups can be attached to nanoparticles.
In order to ensure the success of a protocol, it is essential to have a clear and unbiased knowledge base and a reliable source of reference material. When trying to decide the best platform or application to use for a process, it is critical to ensure that the information on which the decision will be based is generic and factual, and not propagated as promotional data.
Magnetic beads have several advantages over alternate non-magnetic bead technologies, and are thus finding increasing application in all areas of life-sciences research and development including drug discovery, biomedicine, bioassay development, diagnostics, genomics and proteomics.
It is well known that most recombinant protein purifications are mainly done through different types of chromatography, explained in our protein purification handbook. However, the use of magnetic particles is a very interesting alternative to these techniques, providing great advantages and simplifying the process in many aspects. The necessary equipment for purification with magnetic particles is simple: we need a magnet or any device capable of creating a magnetic field, and the particles themselves.
As you will find in our protein purification handbook, choosing the right matrix for protein enrichment and purification processes, such as immunoprecipitation or pull-down assays, is an important step in optimizing the efficiency of a protocol. The decision will be based on a number of variables and ultimately depends largely on the nature of the target biomolecule. The goal is to choose a matrix that will not only maximize the final yield, but will also be practical and accessible.
It is well known that most purification processes of recombinant proteins are conducted through chromatographies of different types, mainly in column chromatography. Whether it’s by affinity chromatography, gel filtration or ion exchange chromatography, these already established methods are not exempt from limitations. Research in recent years has allowed us to develop a series of alternatives to chromatography that allow us to avoid many of these limitations.
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).
In purification of recombinant proteins, highly pure samples are rarely obtained with the initial stages of the process. Whether we perform a highly specific affinity chromatography (with histidine tags, for example) or purification with several stages of capture and intermediate purification, there are always contaminants in the final sample. As you will find in our protein purification handbook, these contaminants are molecules that are closely related to the protein to be purified since, if a high-resolution technique is not applied, they can be hardly differentiated from the protein to be purified.
Affinity chromatography allows us to obtain good results and a high level of purity with a single purification step, since a structure that is exclusively found in the recombinant protein is used as a tag. However, this is not possible in all cases. There are proteins that don’t accept changes in their sequence, even if the changes are so minimal as the incorporation of a tag, since the proteins quickly lose their biological activity with any modifications in their structure.
