{"id":8589,"date":"2023-03-28T17:58:25","date_gmt":"2023-03-28T17:58:25","guid":{"rendered":"https:\/\/www.mybiosource.com\/learn\/?page_id=8589"},"modified":"2023-03-28T18:45:12","modified_gmt":"2023-03-28T18:45:12","slug":"troubleshooting-common-problems-during-elisa-experiments","status":"publish","type":"page","link":"https:\/\/www.mybiosource.com\/learn\/troubleshooting-common-problems-during-elisa-experiments\/","title":{"rendered":"Troubleshooting common problems during ELISA Experiments"},"content":{"rendered":"

Principle of Elisa<\/strong><\/span><\/h4>\n
    \n
  • Antigen<\/span> capture ELISA uses an immobilized antibody specific to the antigen of interest to capture the antigen from a sample.<\/li>\n
  • The immobilized antibody is usually coated onto a solid surface, such as a microplate well.<\/li>\n
  • A detection antibody specific to the antigen is then added to the well.<\/li>\n
  • The detection antibody is labeled with an enzyme<\/span>, like horseradish peroxidase<\/span>, that generates a detectable signal when a substrate is added.<\/li>\n
  • After adding the substrate, the resulting signal is measured, usually by spectrophotometry<\/span>.<\/li>\n
  • Antigen capture ELISA can detect a range of biological molecules, including proteins<\/span>, peptides, and small molecules.<\/li>\n<\/ul>\n

    \"\"<\/p>\n

    ELISA Controls and Interpretation of Results<\/strong><\/span><\/h4>\n

    A sample containing the target antigen is added and bound by the capture antibody, and a second anti-target monoclonal antibody<\/span>, known as the detector, is added.<\/p>\n

    The ELISA involves adding reagents in optimized buffers to a microtiter plate coated with an anti-target capture monoclonal antibody<\/span>. After the excess antibody is washed out, a blocking buffer is added to prevent further binding to the plate.<\/p>\n

    The detector antibody may be labeled or a third anti-mouse isotype-specific monoclonal antibody<\/span> may be added, which will be labeled. If an enzyme<\/span> is used as the label, a substrate is added to the wells that produce a colorimetric change when acted upon by the enzyme<\/span>.\u00a0The optical density of the colorimetric change is proportional to the amount of captured antigen in the sample. Controls should be performed with each ELISA run to ensure proper interpretation of results. Common controls include positive and negative controls, blank wells, and quality control samples. Positive controls contain a known amount of the target antigen, while negative controls do not. Blank wells contain no samples or reagents and are used to measure background signals. Quality control samples are used to verify the accuracy and precision of the assay.<\/strong><\/p>\n

    Elisa Problems and Solutions<\/strong><\/span><\/h4>\n

    Blank (B)<\/strong><\/p>\n

    ELISA uses B control wells that are not exposed to sample or detector antibodies and are used to control for plate variation. An elevated OD in the blank well may suggest a problem with the plate washer, which requires further investigation.\u00a0The problem might be due to a clogged tube or an excess substrate, which could lead to elevated ODs.<\/p>\n

    Zero Concentration (ZC)<\/strong><\/p>\n

    The ZC control in ELISA is similar to the blank but includes all buffers and reagents used in the assay. It helps determine the background of the assay and is necessary to calculate the true limit of detection.\u00a0Consistent control values across runs are important, and signal changes require investigation. Proper care and maintenance of the plate washer can prevent many assay problems, but reagent preparation, storage, and delivery should also be checked.<\/p>\n

    Nonspecific binding (NSB)<\/strong><\/p>\n

    The NSB control is another variation of the blank and zero concentration controls in ELISA.\u00a0It involves adding blocking or wash buffer in place of the reagents at each step of the assay, except for the labeled detector antibody.\u00a0This allows assessment of the contribution of the labeled detector antibody to the overall OD signal of the assay.\u00a0Desired OD results for NSB wells are slightly higher than the B control wells, but not higher than the ZC wells.\u00a0Any differences in the signal can be attributed to the performance of the labeled detector antibody and may require investigation.<\/p>\n

    Proper reagent preparation and delivery are critical for accurate results in this control and the rest of the assay.<\/p>\n

    Maximum Binding<\/strong><\/p>\n

    Maximum binding control is used to estimate the upper limit of the signal generated by the assay. This control is necessary for calculating the % bound of the sample and can help identify issues with the sample, substrate, or detector antibody.<\/p>\n

    Challenges and Solutions in Immunoassay Systems<\/strong><\/span><\/h4>\n

    To avoid this BG noise problem, many commercial diagnostic kits employ an alternative assay system such as the monoclonal antibody<\/span>-based competitive ELISA.\u00a0The most common and critical errors in assaying antibodies by an indirect ELISA system are the employment of poor blocking buffers and failure to subtract the BG OD values in antigen-uncoated wells from the OD values in antigen-coated wells. The basic concept of non-specific reactions should be taken into consideration in any type of immunoassay system because various types of non-specific reactions are involved in any system to a certain extent.<\/p>\n

    The use of assays that measure specific antibodies in samples is important in disease and ecological immunology<\/span> research. However, researchers often face two issues: a lack of assays and reagents for non-model species and the statistical determination of the cut-off threshold used to distinguish samples with and without antibodies.<\/p>\n

    Two solutions are presented. Firstly, using two assays with different detection methods can validate the use of reagents in non-model species. Secondly, a simple way to determine whether samples are from one or two groups of individuals can be used to determine the cut-off threshold for positive and negative samples. These approaches can be useful for applying immune-based assays in ecological immunology and disease ecology research.<\/p>\n

    A new ELISA buffer, ChonBlock, prevents non-specific reactions and can be used to study antibodies against various antigens. The buffer helped identify low IgG antibody responses to potential pathogenic environmental factors<\/span> as a fundamental disorder in autoimmune<\/span> diseases.<\/p>\n

    \u00a0<\/strong>Suggestions<\/strong><\/span><\/h4>\n

    Inconsistent or inaccurate results can be due to various factors such as improper use of reagents, unequal incubation, incorrect pipetting technique, cross-contamination, and low-quality ELISA kits. To ensure consistent and accurate results,<\/p>\n

      \n
    • Reagents should be fresh, properly diluted, and mixed well before pipetting onto the plates.<\/li>\n
    • Plate sealers should be used during incubation, and the substrate should be incubated in the dark to avoid inaccurate readings.<\/li>\n
    • Plates should not be stacked in the incubator, as this can cause uneven temperature distribution and edge effects.<\/li>\n
    • During pipetting, tips should be changed when working on different samples, and cross-contamination should be avoided by not letting the pipette touch the bottom of the well.<\/li>\n
    • A high-quality ELISA kit with a low black value and good adsorption should be chosen to avoid interference with the color reaction.<\/li>\n
    • The quality of the kit should also be checked by adding human IgG<\/span> and anti-human IgG antibodies before and after washing the wells and calculating the average of all values.<\/li>\n<\/ul>\n

      Following good laboratory practices, paying attention to detail, and using proper handling and storage of reagents can help to obtain accurate and consistent results in ELISA experiments.<\/p>\n

      Reference<\/strong><\/span><\/p>\n

        \n
      1. https:\/\/www.myassays.com\/common-elisa-problems-and-solutions.html, James E. Drummond Ph.D<\/li>\n
      2. Assay of\u00a0Chlamydia pneumoniae<\/em>-Specific IgM Antibodies by ELISA Method\u2015Reduction of Non-Specific Reaction and Resetting of Serological Criteria by Measuring IgM Antibodies -Toshio Kishimoto,\u00a0Shuji Ando,\u00a0Kei Numazaki,\u00a0et.al<\/li>\n
      3. \u201cPreventing further misuse of the ELISA technique and misinterpretation of serological antibody assay data \u201c- Kuniaki Terato, Christopher Do, Jessica Chang, Takaki Waritani, Chondrex<\/li>\n
      4. \u201cInterpreting ELISA analyses from wild animal samples: Some recurrent issues and solutions\u201d, Romain Garnier,\u00a0Ra\u00fcl Ramos,\u00a0Ana Sanz-Aguilar,\u00a0Maud Poisbleau,\u00a0Henri Weimerskirch,\u00a0Sarah Burthe,\u00a0Jeremy Tornos,\u00a0Thierry Boulinier<\/li>\n
      5. \u201cPreventing intense false positive and negative reactions attributed to the principle of ELISA to re-investigate antibody studies in autoimmune diseases\u201d, Author links open overlay panelKuniaki\u00a0Terato\u00a0a<\/sup>,\u00a0Christopher T.\u00a0Do\u00a0a<\/sup> Dawn Cutler a<\/sup>,\u00a0Takaki\u00a0Waritani\u00a0a<\/sup>,\u00a0Hiroshi\u00a0Shionoya<\/li>\n
      6. Kuo HT, Yeh JZ, Wu PH, Jiang CM, Wu MC. Application of immunomagnetic particles to enzyme-linked immunosorbent assay (ELISA) for improvement of detection sensitivity of HCG.\u00a0J Immunoassay Immunochem.\u00a02012;33(4):377-87.\u00a0[PubMed]<\/li>\n
      7. Tiscione NB. The Validation of ELISA Screening According to SWGTOX Recommendations.\u00a0J Anal Toxicol.\u00a02018 Apr 01;42(3): e33-e34.\u00a0[PubMed]<\/li>\n<\/ol>\n

         <\/p>\n","protected":false},"excerpt":{"rendered":"

        Principle of Elisa Antigen capture ELISA uses an immobilized antibody specific to the antigen of interest to capture the antigen from a sample. The immobilized antibody is usually coated onto a solid surface, such as a microplate well. A detection antibody specific to the antigen is then added to the well. The detection antibody is […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"class_list":["post-8589","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/pages\/8589","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/comments?post=8589"}],"version-history":[{"count":0,"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/pages\/8589\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.mybiosource.com\/learn\/wp-json\/wp\/v2\/media?parent=8589"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}