Principle of Assay
Universal TNF alpha ELISA Kit (A335458) is a 3 hour indirect Enzyme-Linked Immunosorbent Assay (iELISA) designed for the in vitro quantitative determination of universal TNF alpha in serum, plasma, cell culture supernatant, cell or tissue lysate, and other biological fluids. A 96-well microtiter plate has been pre-coated with assay-specific antigen. Standards and samples are added to the wells, where TNF alpha binds to the immobilized antigen. Following incubation, unbound components are removed by washing and an enzyme-conjugated detection antibody is added to the wells. This detection antibody binds the captured TNF alpha to form an indirect immune complex. After further incubation and washing, TMB substrate solution is added to visualize the enzyme-mediated reaction. This produces a blue-coloured product that changes to yellow following addition of acidic stop solution. The intensity of the yellow colour is directly proportional to the amount of TNF alpha present in the sample. The concentration of TNF alpha is calculated by reading the absorbance at 450 nm and comparing the values with the standard curve.