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ELISA (Enzyme-Linked Immunosorbent Assay)

ELISA (Enzyme-Linked Immunosorbent Assay) is a laboratory technique used to detect and measure proteins, antibodies, antigens, and hormones in biological samples.

  • Principle: An antigen or antibody is immobilized on a plate → the target binds specifically → an enzyme-linked detection system generates a measurable signal (colorimetric, fluorescent, or luminescent).

  • Main Types:

    • Direct ELISA – antigen is detected by a labeled antibody.

    • Indirect ELISA – detection uses a primary antibody and a labeled secondary antibody.

    • Sandwich ELISA – captures the analyte between two antibodies for high specificity.

    • Competitive ELISA – signal decreases as analyte concentration increases.

  • Applications:

    • Medical diagnostics (HIV, COVID-19, hormone levels, allergies).

    • Pharmaceutical and biotech quality control (e.g., host cell protein detection).

    • Research in immunology, oncology, microbiology, and molecular biology.