AVS 52nd International Symposium
    DNA Topical Conference Monday Sessions
       Session DN-MoP

Paper DN-MoP4
In-situ Observation of DNA Immobilization and Hybridization on Si by Surface Infrared Spectroscopy

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: DNA Poster Session
Presenter: K. Ishibashi, Tohoku University, Japan
Authors: K. Ishibashi, Tohoku University, Japan
R. Yamaguchi, Tohoku University, Japan
K. Miyamoto, Tohoku University, Japan
Y. Kimura, Tohoku University, Japan
M. Niwano, Tohoku University, Japan
Correspondent: Click to Email
We have previously proposed a label-free DNA sensing method by the use of infrared absorption spectroscopy (IRAS) in the multiple internal reflection (MIR) geometry, and demonstrated that hybridization of DNA oligomers dissolved in a buffer solution exhibits specific infrared spectral changes.@footnote 1@ In order to apply our method to DNA chips, we need to immobilize single-stranded DNA (ssDNA) oligomers, which are called "probe DNA", on a Si substrate surface. Furthermore, we need to control on the molecular scale the DNA immobilization process on Si to accomplish a precise analysis of DNA on a chip surface. In this study, we have used MIR-IRAS to in-situ investigate the chemical state of a Si substrate surface at each stage of DNA immobilization process, and to in-situ detect hybridization of immobilized DNA oligomers. MIR-IRAS has quite high surface-sensitivity because of the large number of internal reflections, and enables us to in situ monitor the chemical state of a Si surface in aqueous solution. Thiol-modified, 20-based ssDNA oligomers were immobilized on a Si surface that was modified with 3-aminopropyltrimethoxysilane (APTMS) andã??sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SSMCC). On the basis of IRAS data, we confirmed that ssDNA oligomers were immobilized on a Si surface through covalent bonds. The immobilized ssDNA oligomers were subsequently hybridized with complementary ssDNA oligomers in a sodium chloride solution. We observed specific IR spectral structures at the region of 1600 to 1750 cm-1 that are due to DNA hybridization. The present results indicate that MIR-IRAS is a promising technique used for a label-free DNA sensing device. @FootnoteText@ @footnote 1@ Miyamoto K, Ishibashi K, Hiroi K, Kimura Y, Ishii H, Niwano M, Appli Phys. Lett. 86 (2005) 053902-1.