AVS 52nd International Symposium
    DNA Topical Conference Tuesday Sessions
       Session DN+BI-TuM

Paper DN+BI-TuM11
In-situ Infrared Spectroscopic Study of Protonation of DNA Aggregated at Electrode Surfaces in Aqueous Solution

Tuesday, November 1, 2005, 11:40 am, Room 311

Session: DNA Surface Characterization
Presenter: K. Miyamoto, Tohoku University, Japan
Authors: K. Miyamoto, Tohoku University, Japan
K. Ishibashi, Tohoku University, Japan
R. Yamaguchi, Tohoku University, Japan
Y. Kimura, Tohoku University, Japan
H. Ishii, Tohoku University, Japan
M. Niwano, Tohoku University, Japan
Correspondent: Click to Email
Recently we have proposed a method of monitoring hybridization of nucleic acids using infrared absorption spectroscopy (IRAS) in the multiple internal reflection geometry (MIR). The advantages of our method are follows: (1) Fluorescence labeling is not necessary for detection of DNA hybridization (label-free), (2) IRAS provide us with valuable information about conformations of biomolecules, and (3) MIR-IRAS enable us to in-situ monitor biomolecules in aqueous solution. We confirmed that hybridization of DNA can be detected through infrared spectral profiles: Formation of hydrogen bonding between complementary single-stranded (ss-) DNAs induced specific spectral changes in the frequency region of 1600-1750 cm@super -1@.@footnote 1@ Additionally, we demonstrated that when a positive potential is applied to the Si MIR-prism, negatively-charged ss-DNA molecules are aggregated on the prism surface, and that those aggregated ss-DNA molecules show infrared spectral profiles that are quite different from those of isolated DNA molecules floating in the solution. In this study, we have investigated the infrared spectral changes caused by DNA aggregation at an electrode (anode) surface in aqueous solution. By comparing previous IRAS data obtained for the base protonation under acidic condition, we determine that the observe spectral changes are due to protonation of the bases of DNA in the vicinity of the anode (Si MIR-prism) surface where electrochemical reactions generate a large number of protons. Results of ab-initio calculations support our interpretation. @FootnoteText@ @footnote 1@K. Miyamoto, K. Ishibashi, K. Hiroi, Y. Kimura, H. Ishii, M. Niwano, Appl. Phys. Lett. 86, 053902 (2005).