ELISA Immunoassays

Popular ELISA Assays

Assay kits can be convenient time-saving tools to help accelerate your research, but not all assays are created equal. Some that promise convenience fail to deliver biologically relevant sensitivity, or the reproducibility needed for long-term studies. This can cost you more time and money in the end. Whether you use an ELISA assay for biomarker detection, assess cellular function with fluorescent probes, or screen enzyme modulators with activity assays, every Enzo assay kit includes something a lot of other companies out there today can’t — experience.

It takes more than just an antibody pair to make an ELISA. Building an immunoassay requires screening multiple antibodies, selection of appropriate standards and conjugates, establishing proper sample prep protocols, and validation of the assay in relevant matrices. Our expertise in developing ELISAs is further backed by two decades of manufacturing excellence. Strict validation criteria and state-of-the-art manufacturing facilities deliver reproducible assays that continue to be cited in peer-reviewed publications by scientists around the world.

Reliable Manufacturing Ensures Consistent Results

Immunometric assays, also known as sandwich ELISAs (enzyme-linked immunosorbent assay), use two antibodies specific to the antigen to capture or “sandwich” an antigen in the well for detection. Immunometric assays exhibit a direct correlation between antigen concentration and substrate response, and typically employ a “capture” antibody coated on the plate to bind the antigen of interest. A second detection antibody is incubated to bind to the antigen. The detection antibody can either be bound by a tertiary antibody-enzyme conjugate, or the detection antibody itself conjugated with a reporter enzyme. When chromogenic substrate reacts with the reporter enzyme to develop color, samples with high antigen concentration generate more signal than those with low antigen concentration, producing a signal directly proportional to the amount of antigen in the sample. This correlation can then be used to extrapolate the concentration of antigen in an unknown sample from a standard curve.

In competitive enzyme immunoassays (EIA) the antigen in a sample competes for limited antibody binding sites with antigen conjugated to a reporter enzyme. This produces an inverse relationship between antigen concentration and substrate turnover. Competitive EIAs typically use a single antibody to a small molecular weight antigen, generally less than 10,000 Daltons. During incubation, samples with high antigen content result in unlabeled antigen being bound in greater amounts than conjugated antigen. When chromogenic substrate is added to the assay to develop color, samples with high antigen concentration generate a lower signal than those containing low antigen concentration, yielding the inverse correlation between antigen concentration in the sample and strength of the signal in the assay. This relationship can then be used to extrapolate antigen concentration in an unknown sample from a standard curve. This type of reaction is one of the few methods possible for small molecular weight antigens, such as steroids, drugs, lipids and peptides.

Popular ELISA Assays

Reliable detection of analytes that are present at low concentrations is a critical need for early detection of various diseases. Enzo has developed a highly sensitive ELISA Amplification System to be used with your most difficult-to-detect markers.

• Increase sensitivity up to 50-fold over traditional ELISA kits
• Minimal additional time needed to complete amplification step
• Flexible format for use with any immunometric, sandwich ELISAs where greater sensitivity is desired
• Convenient one or five 96-well plate sizes for high throughput analysis
• Easy-to-use, simple procedure with nominal ELISA protocol modification