SAMs terminated with a nitrilotriacetic acid (NTA-SAM) chelating agent bind Ni(II) and the His-Tag motif selectively and tightly. Consequently, they are ideal constructs for selective immobilization of His-tagged proteins (human TATA box binding protein, transcriptional activator Gal 4, two components of the yeast RNA polymerase II holoenzyme, and a single chain T-cell receptor construct) through complexation of the Ni(II) atom by two histidines. See: Sigal, G.B.; Bamdad, C.; Barberis, A.; Strominger, J.; Whitesides, G.M. Anal. Chem., 1996, 68, 490.