AVS 52nd International Symposium
    DNA Topical Conference Monday Sessions
       Session DN+BI-MoA

Paper DN+BI-MoA7
Detection of DNA Hybridization on Porous Silicon Surface by Infrared Microspectroscopy

Monday, October 31, 2005, 4:00 pm, Room 311

Session: DNA Detection and Sensing
Presenter: R. Yamaguchi, Tohoku University, Japan
Authors: R. Yamaguchi, Tohoku University, Japan
K. Ishibashi, Tohoku University, Japan
K. Miyamoto, Tohoku University, Japan
Y. Kimura, Tohoku University, Japan
M. Niwano, Tohoku University, Japan
Correspondent: Click to Email
We propose a label-free method of detecting DNA hybridization by using porous silicon (por-Si) in conjugation with infrared (IR) microspectroscopy. In our method, DNA hybridization is detected through an analysis of infrared spectral profiles, and therefore fluorescence tags are not necessary for the hybridization detection. By using a por-Si film as the chip substrate, we can immobilize a great number of DNA molecules in a small surface area on the chip surface, since por-Si has a quite large effective surface area as compared to a flat Si surface. This may facilitate a high-sensitive detection of DNA hybridization on a small spot. In this study, we have investigated the feasibility of our method by measuring infrared absorption spectra of DNA molecules on por-Si film surfaces. We prepared a por-Si film with straight pores by anodizing a heavy-doped n-type silicon (100) wafer in a mixture of dilute hydrofluoric acid and ethanol. The diameter of straight pores was approximately 25 nm. Single-stranded DNA (target DNA) with 20 bases was immobilized on the por-Si film surface, and then the film surface was exposed to two kinds of probe DNA; one is complementary to the target DNA, and the other is not complementary to the target DNA. We utilized an IR microspectrometer to measure IR absorption spectra of the film before and after exposure to probe DNAs. The working area of the microspectrometer was set at 50Ã-50 µm2. For complementary DNA, we observed absorption peaks due to the probe DNA even after the film surface was rinsed with sodium chloride solution. For non-complementary case, on the other hand, no spectral changes were observed. These observations imply that DNA hybridization can be detected using IR microspectroscopy in conjugation with a por-Si based chip.