The ELISA method is a benchmark for quantitation of pathological antigens and there are indeed many variations to this method. ELISAs are adaptable to high-throughput screening because results are rapid, consistent and relatively easy to analyze. The best results have been obtained with the sandwich format, utilizing highly purified, prematched capture and detector antibodies. The resulting signal provides data which is very sensitive and highly specific.
The principle of Sino Biological Inc. ELISA kit is based on the solid phase sandwich enzyme immunoassay technique. The capture antibody is pre-coated onto well plate strips. Standards and samples are added to the wells and target protein present in the sample is bound by the immobilized antibody. After incubation the wells are washed and a horseradish peroxidase conjugated anti-target protein antibody is added, producing an antibody-antigen-antibody "sandwich complex". Following a wash to remove any unbound antibody a TMB substrate solution is loaded and color develops in proportion to the amount of target protein bound. The reaction is stopped by the addition of a stop solution and the intensity of the color can be measured at 450 nm (See schematics below).