Enzyme-Linked Immunosorbent Assay (ELISA)
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Enzyme-Linked Immunosorbent Assay (ELISA)


Enzyme-linked immunosorbent assay (ELISA) is a labeled immunoassay that is considered the gold standard of immunoassays. This immunological test is very sensitive and is used to detect and quantify substances, including antibodies, antigens, proteins, glycoproteins, and hormones.

The enzyme-linked immunosorbent assay (ELISA) is an immunological assay commonly used to measure antibodies, antigens, proteins and glycoproteins in biological samples. Some examples include: diagnosis of HIV infection, pregnancy tests, and measurement of cytokines or soluble receptors in cell supernatant or serum.

Here at Seattle Genova, we formulate technical service routes according to customer needs (qualitative and quantitative). The entire experimental process will include strict quality control and can help customers with data analysis.


ELISA services provided by Seattle Genova:

1. Direct ELISA

In a direct ELISA, antigens are immobilized directly onto the plate's surface via passive adsorption and detected using HRP-labeled primary antibodies. A coloreless substrate is introduced to the sample, which reacts with the enzyme conjugate, and produces a measurable byproduct. Depending on the choice of substrate, this byproduct can be either colorimetric, chemiluminescent or fluorescent. The magnitude of signal production is proportional to the amount of antigen in the sample. Of all the ELISA formats, direct ELISA assays are the simplest and quickest to perform, however, they are the least sensitive.

2. Sandwich ELISA

Sandwich ELISA assays are the most commonly used ELISA format. It requires the use of matched antibody pairs whereby each antibody is specific for different non-overlapping epitopes on the antigen. One of the antibodies, known as the capture antibody, is first coated onto the surface of a multi-well microtiter plate to facilitate the immobilization of the target antigen. Then the second antibody, known as the detection antibody, binds to the capture antibody-antigen complex (hence the term ‘sandwich’ as the antigen is bound between the matched antibody pairs). Finally, an enzyme-labeled secondary antibody conjugate specific for the detection antibody (and not the capture antibody) is added. Once the secondary binds to the detection antibody, the enzyme-labeled secondary antibody catalyzes a reaction with its respective substrate to produce a measurable signal.

3. Competitive ELISA

Competitive ELISA is a strategy that is commonly used when the antigen is small and has only one epitope or antibody binding site. One variation of this method consists of labeling purified antigen instead of the antibody. Unlabeled antigen from samples and the labeled antigen competes for binding to the capture antibody. A decrease in signal from the purified antigen indicates the presence of the antigen in samples when compared to assay wells with labeled antigen alone.

4. Reverse ELISA

The reverse ELISA test leaves the antigens suspended in the test fluid. It allows multiple antigens to be tagged and counted at the same time.  Specific strains of bacteria can be identified by two (or more) different color tags.  If both tags are present on a cell, then the cell is that specific strain.  If only one is present, it is not.


Workflow of Our Service

Accept orders and samples

Develop suitable ELISA protocols

Carry out experiments and get results

Deliver the results to the customer


Sample Requirements

Samples (culture supernatant, serum, plasma, etc.) should be stored at -20°C to avoid repeated freezing and thawing. All samples should be shipped with dry ice.


Deliverables

Test report.

Enzyme-Linked Immunosorbent Assay (ELISA)


Enzyme-linked immunosorbent assay (ELISA) is a labeled immunoassay that is considered the gold standard of immunoassays. This immunological test is very sensitive and is used to detect and quantify substances, including antibodies, antigens, proteins, glycoproteins, and hormones.

The enzyme-linked immunosorbent assay (ELISA) is an immunological assay commonly used to measure antibodies, antigens, proteins and glycoproteins in biological samples. Some examples include: diagnosis of HIV infection, pregnancy tests, and measurement of cytokines or soluble receptors in cell supernatant or serum.

Here at Seattle Genova, we formulate technical service routes according to customer needs (qualitative and quantitative). The entire experimental process will include strict quality control and can help customers with data analysis.


ELISA services provided by Seattle Genova:

1. Direct ELISA

In a direct ELISA, antigens are immobilized directly onto the plate's surface via passive adsorption and detected using HRP-labeled primary antibodies. A coloreless substrate is introduced to the sample, which reacts with the enzyme conjugate, and produces a measurable byproduct. Depending on the choice of substrate, this byproduct can be either colorimetric, chemiluminescent or fluorescent. The magnitude of signal production is proportional to the amount of antigen in the sample. Of all the ELISA formats, direct ELISA assays are the simplest and quickest to perform, however, they are the least sensitive.

2. Sandwich ELISA

Sandwich ELISA assays are the most commonly used ELISA format. It requires the use of matched antibody pairs whereby each antibody is specific for different non-overlapping epitopes on the antigen. One of the antibodies, known as the capture antibody, is first coated onto the surface of a multi-well microtiter plate to facilitate the immobilization of the target antigen. Then the second antibody, known as the detection antibody, binds to the capture antibody-antigen complex (hence the term ‘sandwich’ as the antigen is bound between the matched antibody pairs). Finally, an enzyme-labeled secondary antibody conjugate specific for the detection antibody (and not the capture antibody) is added. Once the secondary binds to the detection antibody, the enzyme-labeled secondary antibody catalyzes a reaction with its respective substrate to produce a measurable signal.

3. Competitive ELISA

Competitive ELISA is a strategy that is commonly used when the antigen is small and has only one epitope or antibody binding site. One variation of this method consists of labeling purified antigen instead of the antibody. Unlabeled antigen from samples and the labeled antigen competes for binding to the capture antibody. A decrease in signal from the purified antigen indicates the presence of the antigen in samples when compared to assay wells with labeled antigen alone.

4. Reverse ELISA

The reverse ELISA test leaves the antigens suspended in the test fluid. It allows multiple antigens to be tagged and counted at the same time.  Specific strains of bacteria can be identified by two (or more) different color tags.  If both tags are present on a cell, then the cell is that specific strain.  If only one is present, it is not.


Workflow of Our Service

Accept orders and samples

Develop suitable ELISA protocols

Carry out experiments and get results

Deliver the results to the customer


Sample Requirements

Samples (culture supernatant, serum, plasma, etc.) should be stored at -20°C to avoid repeated freezing and thawing. All samples should be shipped with dry ice.


Deliverables

Test report.

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