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Quality Control of in Vitro Diagnostic Reagents

The raw materials of in vitro diagnostic reagents are a breakthrough point in the in vitro diagnostic industry. The quality of in vitro diagnostic products is largely determined by the raw materials of the upstream IVD reagents.


In recent years, the IVD in vitro diagnostic industry has entered the development phase from the introduction phase. With the rapid growth of market demand, companies have seized the opportunity to constantly seize market share by relying on the advantages of high cost-effective products and more tailored products to the local market, which has gradually broken the raw material market structure that was dominated by imported products. With the rapid development of the in vitro diagnostic industry, innovative, high-quality, stable, and large-volume in vitro diagnostic reagent raw materials companies have emerged, and they are increasingly valued and favored by in vitro diagnostic reagent manufacturers.


So, how to ensure the high quality of IVD raw materials is very important. The following content mainly summarizes the quality control of antigen and antibody diagnostic materials.


Ⅰ. Quality control of in vitro diagnostic reagents


1. Raw material quality control


Including the quality control of animal sources, medium quality control, biological safety testing, etc. IVD raw materials are not simply a protein preparation, but also need to consider the specificity, sensitivity, batch-to-batch difference, purity and other properties of the raw materials.


2. Quality control of cell bank


The preparation of antibody diagnostic materials is inseparable from hybridoma cells. The viability of hybridoma cells will gradually decline after several passages. If the cell line is not well preserved and is contaminated, the impact on antibody raw materials will also be severe. Therefore, the scientific preservation, recovery and passage of cell lines is very necessary.


At present, a few manufacturers of antigen-antibody diagnostic raw materials adopt in vitro recombinant expression methods to obtain IVD raw materials to ensure the purity of raw materials and batch-to-batch performance. The expression system includes prokaryotic expression and mammalian expression.


3. Production and purification


The production methods of antibody raw materials are mainly divided into in vivo culture and in vitro culture. In vivo culture is obtained by culturing mouse ascites, while in vitro culture is obtained by bioreactor. Due to animal protection issues and potential differences between individual animals, in vitro antibody production may become the main production method. The current purification methods of raw materials are mainly affinity chromatography and ion exchange chromatography. For monoclonal antibodies, protein A/G affinity chromatography is the main method; for polyclonal antibodies, high-purity antigen affinity is used. Chromatography is the main method; for antigens, affinity purification is mostly used.


Ⅱ. Factory quality inspection of in vitro diagnostic reagents


1. Appearance: Observed by naked eyes, most of the in vitro diagnostic reagent materials are clear and uniform liquids, free of foreign bodies, turbid or lingering precipitates or particles; or white powders and do not contain other impurities.


2. Purity and molecular weight: The main method is SDS-PAGE electrophoresis and staining with Coomassie brilliant blue or silver staining, and then scanning and analyzing the bands. In addition, high performance liquid chromatography can also be used for purity and molecular weight determination. As an IVD raw material for in vitro diagnostic reagents, the purity is generally greater than 90% after staining with silver staining; the purity is generally greater than 95% after staining with Coomassie brilliant blue.


3. Protein concentration: The main measurement methods are Lowry method, OD280nm light absorption method and biuret method. It should be noted that there are certain differences in the results between different methodologies, so it is recommended that the method consistent with the raw material manufacturer be used for verification.


4. Antibody titer: The titer is generally determined by the method of multiple dilution based on the guaranteed content determination result, and the titer should meet the specified requirements.


5. Functionality: including specificity, sensitivity, stability, batch-to-batch difference, precision and other functional analysis, and compare its correlation with the previous batch of raw materials.