Oriented immobilization of antibodies by a self-assembled monolayer of 2-(biotinamido)ethanethiol for immunoarray preparation

Orientation of antibodies is very important in the preparation of immunoarrays to keep the activity of antibodies on solid surfaces. Thus, we synthesized a new bifunctional compound, 2-(biotinamido)ethanethiol, and investigated whether the thiol compound is useful to analyze antibody–antigen interactions on immunoarrays with a spectral SPR biosensor. The synthesized organic thiol was characterized by nuclear magnetic resonance spectroscopy and mass spectrometry. 2-(Biotinamido)ethanethiol formed a monolayer on a gold surface and properly immobilized antibodies via streptavidin and biotinylated protein G. Optimal molar ratio of 2-(biotinamido)ethanethiol and mercaptohexanol for antigen–antibody interactions was 1:2. Thus, 2-(biotinamido)ethanethiol is an useful bifunctional linker in the preparation of immunoarrays on gold surfaces.