Affiliation: | (1) Department of Chemistry, Building 207, Technical University of Denmark, 2800 Lyngby, Denmark;(2) Institute of Micro- and Nanotechnology, Building 345 East, Technical University of Denmark, 2800 Lyngby, Denmark;(3) Department of Physics and Department of Chemical Engineering, ICAT (Interdisciplinary Research Center for Catalysis), Technical University of Denmark, Building 309-312, 2800 Lyngby, Denmark |
Abstract: | We provide a comprehensive study of single- (ss) and double-strand (ds) oligonucleotides with either 25 or 10 bases or base pairs (bp) immobilized on polycrystalline and single-crystal Au(111) surfaces. The study is based on X-ray photoelectron spectroscopy, cyclic and differential pulse voltammetry, interfacial capacitance data, and electrochemical scanning tunnelling microscopy (in situ STM). The sequences used were the 25-bp sequence from the BRCA1 gene (25-mer), while the 10-bp oligonucleotides contained solely linear adenine and thymine sequences. The oligonucleotides were modified by the dimethoxytrityl group (DMT) via a disulfide group [DMT-S-S-ss25-mer and DMT-S-S-ds(AT)10], a pure disulfide group (A10-S-S-T10), or a thiol group [HS-ss25-mer and HS-ds-(AT)10], all via a hexamethylene linker. The overall pattern suggests strategies for controlled adsorption of DNA-based molecules and recognition of complementary strands or other molecules. |