Question

Describe the general principles of antibody based assays in cohesive sentences

Answer 1

Antibodies are proteinaceous molecules which are very specific in nature and bind with specific antigens when together. Since the binding between antigen and antibody is highly specific, this reaction is used to detect the presence of various antigens by conducting various assays. Generally in an assay, antigens are ligated in a substratum. Antibodies tagged with coloured molecules are applied to them and then washed. If there are antigens specific to those antibodies are present then they will bind together and form some colourations, and won't form any colouration if there is no antigen (hence no binding).

Example of such is ELISA (enzyme linked immunosorbent assay).

Here there is a layer of primary antibodies first. Then antigens bind with them, then there are secondary antibodies with tagged substrates which bind to the antigen in a sandwich method. When enzyme is added ,the linked substrate shows colouration showing the presence of antigen.

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