Thiol-mediated anchoring of ligands to self-assembled monolayers for studies of biospecific interactions.

We report a method to immobilize thiol-containing ligands onto self-assembled monolayers (SAMs) of alkanethiolates presenting chloracetylated hexa(ethylene glycol) groups. The chloroacetyl groups react with thiols under mild basic conditions, enabling the stable immobilization of biologically active ligands in a well-defined orientation. These SAMs on gold are well suited for studies of biospecific interactions of immobilized ligands with proteins and cells. As a demonstration, we functionalized these SAMs with thiol-containing derivatives of biotin and benzene sulfonamide and observed the specific binding of neutravidin and carbonic anhydrase, respectively. We also used this method to generate mixed SAMs presenting the Arg-Gly-Asp (RGD) peptide sequence and demonstrated the integrin-mediated adhesion of fibroblast cells to these SAMs. This approach would allow the immobilization of proteins and other sensitive biomolecules and ligands for a wide variety of applications in biotechnology.