The force of gravity will cause sedimentation of particles from a heterogeneous mixture; larger and denser particles sedimentfaster than the smaller and less dense particles. This phenomenon is useful for separating heterogeneous solutions into independent components, and for the isolation and enrichment of target molecules, cells, and cell organelles. Differential centrifugation accelerates the separation process by introducing centripetal forces many times greater than gravity. The precipitated particles form a pellet at the bottom of the tube during centrifugation. The rate of sedimentation is dependent on the size and density of the particles, so centrifugation can be used to isolate target particles simply by controlling centrifugal force or the rate of centrifugation. The rate of centrifugation is reported as angular velocity by revolutions per minute (rpm) or as acceleration(g). RPM is dependent on the radius of the rotor in the centrifuge.
From the clinical laboratory ELISA to the home pregnancy test, the conjugated antibody is integral to the function of many diagnostic assays. We know about the specificity of antigen-antibody interactions and their role in mounting the innate immune response to a pathogen. This antigen recognition specificity has been utilized by clever scientists and engineers to create biosensors capable of detecting the presence of antigens in biological samples. Biosensors come in many shapes and sizes, and have varying levels of complexity, but one fundamental concept is the need to covalently attach antibodies to a substrate.
An elution buffer plays an essential role in every immunoprecipitation protocol or assay that requires the release of a target antigen from a capture antibody. Elution buffers are necessary in protocols utilizing a stationary affinity column, and are also required in protocols using mobile solid supports in solution.
Protein A vs Protein G both are bacterial cell wall proteins that have primary binding sites for human and mammalian immunoglobulin G (IgG) antibodies. Protein G was first isolated from Streptococcal bacteria strains C and G. Similarly, protein A was originally found on the cell wall of the bacteria Staphylococcus aureus. These proteins have primary binding domains for the Fc region of (IgG) antibodies, but can also recognize the Fab region of certain IgG subclasses. For the bacteria this is useful because binding IgG’s at the Fc region prevents macrophages from recognizing them, which in turn prevents phagocytosis of the invading bacteria by the host immune system.
The China Association for Chemical Laboratory Practice (CACLP) Expo is the biggest and most influential IVD-exhibition in the Asian giant. We attended the 2018 edition, held in the city of Chongqing from March 17th to March 19th. Here are the impressions about the event of some colleagues and our CSO.
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.
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 bead suspensions will eventually sediment and aggregate over time. If non-homogeneous biomagnetic separation conditions are used, studies show that the likelihood of irreversible aggregation occurring is very high. Unfortunately, when this happens, lot consistency, lot quality and lot functionality are all compromised. There are several steps during the preparation of magnetic beads for diagnostic kits where irreversible aggregation can become a problem unless resuspension techniques are used that guarantee gentle disaggregation.
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.
Good manufacturing practice is an essential part of the production of human drugs, veterinary drugs, biological and biotechnology products, and pharmaceutical ingredients. These commercial processes are subject to regulatory oversight and must ensure that every aspect of the production process is carefully scrutinized. The purpose of process validation is to collect data and scientifically analyze the production process from conception to large scale production. An updated process validation protocol is essential to ensuring product quality and consistency. Many laws have been established to mandate process validation in order to protect consumers, especially in the case of pharmaceutical products.