Chemically homogeneous, silylated surface for effective DNA binding and hybridization

We report on a method for covalent immobilization of 5 ´-thiol-modified single strand DNA probes, onto oxygen exposing surfaces by exploiting surface derivatization by 3-mercaptopropyltrimethoxysilane and subsequent intermolecular disulfide bond formation. The various steps in the formation of the molecular edifices have been characterized by X-ray photoelectron spectroscopy, quartz crystal microbalance and atomic force microscopy under liquid. Surface reaction kinetics of thiol-modified DNA probes with thiol-bearing silanes turned out to be a second-order one, possibly due to the presence of both free thiol and S-S dimers in solution. The ability of immobilized single strand DNA to bind the complementary strand has been tested and confirmed by quartz crystal microbalance measurements. The presented DNA immobilization method appears to be applicable to any surface bearing exposed hydroxyl moieties.