As we have entered an age of personalized medicine, we have begun to understand that individual differences play a large role in disease expression and treatment options. This idea is also true of individual cells, the basic unit of life. Therefore, when studying disease phenotypes and developing new drugs, it is becoming increasingly important to study single cells instead of groups of cells. The technologies used for single cell isolation have started to improve and it is now possible to isolate single cells for analysis. Oftentimes, this analysis is referred to as cell omics because it covers a wide range of topics including genomics (DNA), transcriptomics (coding and non-coding RNA), proteomics (protein), and metabolomics (the complete set of small-molecule chemicals found within a biological sample). This is a lot of information to gather from such a small, but powerful structure, and it can become very valuable when studying diseases such as cancer, which generally arises from a mutation within a single cell.
Circulating Tumor Cells (CTCs) are cancerous cells that dissociate from a tumor and circulate throughout the bloodstream. Therefore, the detection of CTCs in the bloodstream is an indicator of cancer progression and an early sign of metastasis. CTCs are not hematopoetic in origin, and they do not express the cell surface marker CD45. However, they do express the surface antigen EpCAM, which is commonly expressed on epithelial cells. Immunomagnetic separation methods take advantage of these surface markers to isolate CTCs from centrifuged blood samples.
Regulation of the pharmaceutical development process is important to ensure that drug products are consistently safe and effective. There are written guidelines for pharmaceutical validation, which ensure that drug compounds are handled and tested properly. There are also separate guidelines for the bioanalytical methods used in the development and testing of new drug compounds. The goal is to standardize and improve the consistency of pharmaceutical studies and that data that are used for drug approval. Examples of analytical methods include ligand binding assays and chromatographic methods (liquid chromatography, gas chromatography, and mass spectrometry). Both the FDA (U.S. Food and Drug Administration) and EMA (European Medicines Agency) regularly update their bioanalytical method validation guidelines, but their focuses are slightly different. The FDA outlines reporting guidelines in more detail, while the EMA focuses more closely on the conduction of experiments. The validation guidelines are unified under ICH (International Council for Harmonisation of Technical requirements for pharmaceuticals for human use).
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, the consistency, quality and functionality of the lot 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.
Antibodies are naturally produced by the adaptive immune system in response to invading pathogens. The antibodies are made by immune cells to specifically recognize protein markers called antigens located on the outer wall or membrane of the pathogenic organism. It is this exquisite antigenic specificity that makes the adaptive immune system so remarkable in its ability to fight off a wide variety of diseases. It is also this specificity that makes the antibody-antigen interaction an attractive tool for the development of biological assays for the detection of active infection and disease.
The objective of magnetic activated cell isolation or macs cell sorting is to enrich a specific cell type from a mixed population. The versatility and specificity of magnetic bead cell isolation is made possible by functionalized bead surfaces that specifically recognize a molecule or antigen(link) on the surface of a target cell. Magnetic beads are composed of a ferrous iron-oxide core surrounded by a polymer shell, or a magnetic ‘pigment’ embedded in a polymer matrix.
The BCA protein assay is used to quantify total protein in a biological sample. BCA stands for Bicinchoninic acid, which is the key reagent used to produce a colored product. The purple colored product is analyzed in reference to a standard curve in order to quantify protein concentration. It is important to measure protein concentration after performing a protein extraction or purification, and prior to any type of labeling procedure. The protein concentration after extraction or purification may provide information about a biochemical pathway or a disease state. All commercially available proteins are accompanied by a product information sheet that has the results of a protein quantification method. This is particular important in antibody validation. It is important to know the protein concentration prior to any labeling step so you can ensure that the stoichiometric ratio between label and protein is optimal for clean and efficient labeling. It is equally important to know how much protein you are working with when designing biosensors so that you can define limits of detection and instrument sensitivity.
What is process validation and why do we do process validation?
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.
Process validation in the pharmaceutical industry takes the same form as process validation in all other industries, but the stakes are higher because the product is made for human consumption. Moreover, pharmaceuticals are made to alter the natural biochemical pathways in the human body, so these chemicals must be formulated correctly and consistently every time. Additionally, the products must be stored properly and shipped under climate-controlled conditions in order to ensure efficacy once reaching the consumer.
The ELISA (Enzyme Linked ImmunoSorbent Assay) is the gold star immunoassay, which means that it is the standard procedure that all new assay technology is compared to during research and development. The ELISA is also fundamental to most clinical tests for diagnosis of disease because it is currently the most characterized and standardized method. The ELISA is an immunoassay, the principle of which relies on the specific recognition between an antibody and antigen. This specificity comes from the unique three dimensional structure of the antibody paratope and the antigen epitope. These two regions fit like a lock and key via non-covalent, charge-based, and/or hydrophobic interactions. The clinical purpose of the ELISA is to detect either antibody or antigen from a biological fluid such as blood (serum), urine, or saliva. When the ELISA is used to antibody, the assay is being used to assess whether or not the patient has been exposed to a certain antigen at some point. It is difficult to assess current infection with this method because the body retains antibodies forever after the first introduction. However, elevated amounts of antibody can be indicative of active immune response to the pathogen. One major benefit of the ELISA is that it is quantitative, meaning that an actually number of protein can be evaluated. When the ELISA is used to detect antigen it provides a better understanding of current infection since the antigen would be cleared if it was no longer active in the body.
Biotinylation kit means attaching a biotin tag to a molecule. Biotin is a natural molecule that is also known as vitamin B7. It is an important component in a healthy diet, but it is also very useful in the laboratory as a method for protein conjugation. In the laboratory, he purpose of biotinylation is to create a controlled site for biotin-streptavidin affinity binding.
What is biotin labeling and how does streptavidin bind biotin?
The biotin fits exquisitely into a biotin-binding pocket in each of the four binding sites per streptavidin molecule, and it is held in place with hydrogen bonds. Additionally, once the biotin is bound, a conformational change in the streptavidin allows a small “cap” to close over the biotin in the binding pocket. As a result, biotin and streptavidin have an extraordinary affinity for each other (Kd=10^-15). With such a low dissociation constant, once the biotin and streptavidin are bound it is unlikely that they will dissociate. This affinity is resistant to changes in temperature, pH, and salt concentration and is extremely specific. It is often thought of as a nearly covalent bond. These properties make biotinylation a useful tool for engineers who are developing new purification and detection methods. A commercially available biotinylation kit makes the process even easier.