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#competitive ELISA

3 public questions tagged with this topic.

Flow cytometry, FACS, ELISA

Which is detected in competitive ELISA?

Competitive ELISA is advantageous for small molecules, haptens and subtle structural differences that cannot accommodate two antibodies simultaneously in sandwich format. One antigenic site allows competition between labeled reference and sample antigen for limited antibody. Minor variations in epitope structure alter competitive displacement curves, enabling discrimination of analogs, drug metabolites, hormone isoforms and pesticide residues. Antibody subclass identification needs isotype specific secondaries, protein folding requires biophysical methods, cell counting needs cytometry. Sensit

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Flow cytometry, FACS, ELISA

In competitive ELISA, color presence indicates?

Competitive ELISA measures small antigens where two antibodies cannot bind simultaneously. Wells are coated with reference antigen, sample antigen competes with labeled antigen for limited antibody binding sites. If sample contains abundant target, it occupies antibodies and prevents binding to plate antigen, so labeled complex is washed away and little color develops after substrate addition. Thus strong color indicates antibodies bound plate antigen because no competitor was present, meaning sample was negative for target analyte. Signal is inversely proportional to antigen concentration.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Microscopy

In a competitive ELISA, a positive test result is indicated by:

Competitive ELISA follows an inverse signal principle where sample antigen competes with enzyme-labeled antigen for limited antibody binding sites. When target analyte concentration is high in specimen, it outcompetes labeled competitor, reducing enzyme retained after washing. Consequently substrate conversion declines and absorbance remains low. A strong color would mean labeled antigen successfully bound, indicating little or no competing analyte. Therefore disappearance or marked reduction of color signals positivity, allowing quantification of small molecules like hormones and drugs that c

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

View Details