Department of Energy Engineering(Battery Science and Technology)The enzyme-linked Immunosorbent assay (ELISA) has been developed as a format of a diagnostic tool in medicine recently to detect the presence of an antigen in a liquid sample or wet sample. Especially, sandwich type ELISA has been commonly commercialized and preferred because of high specificity and sensitivity among the systems by using two antibodies to capture and detect its antigens. In addition, immobilization of antibodies is a key process to improve specificity and sensitivity in ELISA. Here we report a novel method to immobilization antibodies on the surface of the solid support with a recombinant antibody binding domain (ABD) fused with mono-streptavidin (mSA). The Z domain derived from protein A which has high binding affinity to the Fc region of various antibodies such as rabbit, rat and mouse. mSA is monomeric form of streptavidin which consists of tetramer and has very high affinity with bioitin (vitamin H). We have genetically inserted ABD with mSA (mSA-ABD) to obtain dual functions separately. mSA-ABD fusion protein is overexpressed in E.coli system and successfully purified by affinity chromatography. The binding affinity of ABD of mSA-ABD is verified with quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) analysis. The other binding affinity of mSA with biotin was confirmed with binding activity test using biotin coated plates. Finally, we treat mSA-ABD as an anchoring adapter molecule in sandwich type of ELISA taking advantage of dual binding affinity and we can obtain the typical ELISA result from the series of experiments.ope