Enzyme-linked Immunosorbent Assays (ELISAs) is a common analytical method for detecting the presence and concentration of antibodies, antigens, proteins, and glycoproteins in a variety of sample types. ELISAs are desirable for their high specificity and sensitivity. There are many variations of ELISAs commonly used in analytical laboratories:
ELISA Methods
Direct ELISA
This method employs a fluorescent or biotin-streptavidin tagged primary antibody that will elicit a readable signal after stimulation and binding to an immobilized antigen.
Indirect ELISA
This is a modified format of the direct ELISA approach that utilizes a tagged secondary antibody that binds to the unlabeled primary antibody of the antibody-immobilized antigen complex. The tag is typically fluorescent or a biotin-streptavidin complex.
Sandwich ELISA
A spin on the indirect ELISA, this method utilizes an immobilized capture antibody to interact with a target antigen. This is followed by a step using an unlabeled primary antibody to bind to the target antigen-capture antibody complex. The final step before signal detection is to use a tagged secondary antibody that is highly specific to the unlabeled primary antibody.
Competitive ELISA
This assay is typically used to determine concentrations of a target antigen in a sample. The process is characterized by an immobilized capture antibody of a specific quantity that is designed to bind to the target antigen and a competing antigen. The tagged target antigen signal is analyzed to determine relative concentration.
Challenges in ELISA Technique and Automation Solutions
Despite the ubiquity of the ELISA technique, numerous reagent additions, washes and incubation steps make ELISAs a complex and labor-intensive procedure with potential for variability in results.
Automation of these steps relieves the labor burden with improved throughput, consistency and high efficiency enabling simultaneous analyses on a single workstation.
Our Danaher Life Sciences companies provide a wide range of solutions and fit-for-purpose technologies for partial or end-to-end ELISA workstations for method development and implementation.