The reactive NHS head-group allows covalent coupling of a variety of molecules onto the monolayer. NHS-activated carboxy-terminated thiols were used, for example, to immobilize B-galactosidase (Ball, J.C. et al. Anal. Chem., 2003, 75, 6932), collagen V and horseradish peroxidase (Zaugg, F.G. et al. J. Mat. Sci Mat. Med., 1999, 10, 255). Biebuyck and coworkers (J. Am. Chem. Soc., 1998, 120, 500) have used thiols terminated with active NHS esters for covalent attachment of antibodies to SAMs for the development of immunosensors. At the same time, owing to the (ethylene glycol) linker, this thiol forms SAMs resistant to nonspecific adsorption. A truly versatile compound!
Note: Since this thiol hydrolizes readily, it should be stored in pure state, at low temperature and under inert-gas atmosphere.