Principle of Assay
Human Surfactant Protein A/PSAP ELISA Kit (A78820) is a 4 hour sandwich Enzyme-Linked Immunosorbent Assay (sELISA) designed for the in vitro quantitative determination of human Surfactant Protein A/PSAP in serum, plasma, tissue homogenates, and other biological fluids. A 96-well microtiter plate has been pre-coated with an antibody specific for Surfactant Protein A/PSAP. Standards and samples are added to the wells, where Surfactant Protein A/PSAP binds to the immobilized capture antibody. Following incubation, unbound components are removed by washing and a biotinylated detection antibody specific for Surfactant Protein A/PSAP is added to the wells. The detection antibody binds the captured Surfactant Protein A/PSAP to form an antibody-antigen-antibody sandwich complex. After further incubation and washing, HRP-Streptavidin conjugate is added to the wells. TMB substrate solution is then added to visualize the HRP enzymatic 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 Surfactant Protein A/PSAP captured in each well. The concentration of Surfactant Protein A/PSAP is calculated by reading the absorbance at 450 nm and comparing the values with the standard curve.