Influence of the thiol position on the attachment and subsequent hybridization of thiolated DNA on gold surfaces

The capability of five different thiol configurations in single-stranded DNA to undergo a chemical bond with a gold surface and then to hybridize with a complementary strand, was investigated. The binding and hybridization were assessed using a colorimetric detection based on an immunological response to a biotin label, an antibody amplified surface plasmon resonance technique, and electrochemical desorption spectroscopy. Successful binding was found for oligonucleotides that were modified with a thiol attached via a carbon chain to the 3′ end. Results show that a better electronic coupling between a metal surface and DNA can be achieved by binding the DNA directly to the metal surface without an insulator linker molecule.