6 Pointers On Selecting Your Next ELISA Kits

ELISA or EIA is a measurement technique for analytes like antigen, glycoproteins, and antibodies. This method studies various biochemical pathways, disease diagnosis, insulin signaling pathways, and oxidative stress. Elisa can determine antibody concentration against the antigen and help detect infectious diseases. It can help diagnose HIV, Lyme disease, Hepatitis B, Syphilis, Zika virus, and other health problems caused by viruses, bacterias, and other pathogens. Recently, researches have indicated that ELISA can provide a crucial supplementary diagnosis of SARS CoV-2. 

Enzyme-linked immunoassay is a useful diagnostic tool for infections in humans, animals, and plant pathology and is helpful in biochemistry, biotechnology, and medicine. ELISA works bilaterally by identifying analytes that are recognized by each other, such as immunoglobulin and antigen. 

The process of ELISA testing is simple. It starts with sample collection and adds it to the Petri-dish that contains high-affinity analytes (antibodies or antigens), depending on the sample. The test will recognize the specific analyte by binding it to the target sample. Further, the precise measurement of analytes is done to determine its amount is present in the specimen. 

Several EIA kits are obtainable in the market with applications ranging from detecting food allergen, pregnancy, and a drug in the body. The most available ELISAs are Direct EIA, Indirect EIA, Sandwich EIA, and Inhibition/Competitive EIA. But with so many options in the market, how would you decide which kit can serve you best? Here are six vital points to remember when you select your next ELISA kit.  

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1. The Study Of Species 

Finding an accurate kit for a classical model like humans and rats are quite common. But for non-classical models like dogs and monkeys, the number of kits reduces considerably. In this case, select target-specific kits that are homologous with the specimen collected from particular species. 

2. Use Of Specialized Kits

Dedicated research domains have specialized kits. Many companies provide assay tools, and others supply laboratory kits. These equipment identify specific proteins, cell proliferation, and protein quantitation. Many molecular biology kits for DNA/RNA purification, amplification, and mutagenesis are also available. Moreover, there are particular EIA kits for non-invasive samples, lipids, and for using an antibody array. A few manufacturers also provide ELISA test kits that consolidate several specialized actions but within a budget.

3. The Sample Used

A wide variety of samples are tested in ELISA that include blood plasma, saliva, and urine. While selecting ELISA, you should ensure that the kit is consistent with your sample. For Instance, complex specimens, like cytokines that require both sensitive and specific results, are determined by the Sandwich kit. Competitive ELISA is used to quantitate small molecules like hapten. 

Other criteria, like plasma collection through heparin or ethylenediaminetetraacetic acid (EDTA) method, also affect the kit choices you make. In a few cases, some conditions, including lipids in the sample, hemolysis, and bovine serum in cell culture, interfere with the diagnosis. Therefore, always learn about the kit in detail before collecting the sample and testing it. 

5. The Data Interpretation

Data Interpretation of ELISA kits falls under different formats. You can use a quantitative method where data interpretation takes place in comparison to a standard curve. You can create this curve by plotting absorbance value against protein concentration. This method calculates the concentrations of antigen or target protein in the sample accurately. 

A qualitative format provides a positive and negative reply, indicating whether the target protein is present or not in a given specimen. Semi-quantitative kits compare the relative levels of target protein in samples as the sample’s absorption varies proportionately with the antigen’s concentration. 

5. The Selection Of Antibodies 

Different types of ELISAs use different antibodies. A direct ELISA kit uses a primary, whereas Indirect ELISA uses both primary and secondary antibodies. A Competition ELISA uses monoclonal antibodies due to their ability to attach to an antigen’s single antigenic determinant. In some cases, polyclonal is used as secondary antibodies with the affinity for various epitopes found in a single antigen. Therefore, always consult the suppliers to know what kind of antibody your kit is using for the test.

6. The Concentration Of Biochemical Marker

If you do not know about the concentration of biochemical markers, select a kit with a comprehensive and dynamic detection range. Here, EIA can perform several dilutions during the validation stage. For samples containing a low level of the target protein, opt for a highly sensitive detection kit. 

The Bottom Line

While purchasing an ELISA kit, the most important is the time investment. Check the detailed description of the EIA to see if it fulfills your requirements. Also, see how many tests you can perform with the kit and the amount of sample it uses for the assay. It might help you calculate the cost-effectiveness of your EIA. Besides, with the 96-well format, the strips are removable, and plates are reusable that enhance the kit’s profitability. The short experiment time, convenient functioning, and easy protocols make ELISA the most reliable and efficient test kit for many acute diseases. 

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