Authors: T. Saito, S. Takahashi, T. Obara, N. Itabashi, K. Imai
Affilation: Hitachi High-Technologies Corporation, Japan
Pages: 117 - 120
Keywords: plasmon, single molecule, fluorescence enhancement, nanostructure
To enable not only long sequence read but also high throughput in a DNA sequencer, the single molecule sequencing method based on direct observation of processive DNA polymerization is very promising. In this method, only incorporated nucleotides labeled with fluorescent dye should be detected under high concentration of unreacted nucleotides. Enhanced local field produced by plasmonic nanostructure is very suitable for such application because of its small size of a few ten nanometers. We have fabricated platinum bowtie nanostructure arrays producing fluorescence enhancement and have evaluated the performance using two-photon photoluminescence and single molecule fluorescence measurements. To enable use of multicolor dye labeling, visible light excitation around 500 nm is preferable, so that gold well known as a plasmonic material cannot be used. We explored suitable materials comprehensively by electromagnetic simulation and consequently chose platinum. Observation of bright photoluminescence from Pt nanostructure indicates clearly that a strong local electric field is created near the nanostructure. We tried to attach single dye molecule into the gap area between Pt triangles by using selective immobilization chemistry. About 20% of the nanostructure showed larger enhancement factor than 10, and a highly enhanced fluorescence up to a factor of 30 was observed.