Monday, April 22, 2013

Permanently Fixing or Reversible Trap-and-Release of DNA Micropatterns on a Gold Nanostructure using Continuous-wave or Femtosecond Pulsed Near-Infrared Laser Light

Tatsuya Shoji, Junki Saitoh, Noboru Kitamura, Fumika Nagasawa, Kei Murakoshi, Hiroaki Yamauchi, Syoji Ito, Hiroshi Miyasaka, Hajime Ishihara, and Yasuyuki Tsuboi
The use of localized surface plasmons (LSPs) for highly sensitive biosensors has already been investi-gated, and they are currently being applied for the optical manipulation of small nanoparticles. The ob-jective of our work is the optical trapping of -DNA on a metallic nanostructure with femtosecond pulsed (fs) laser irradiation. Cw laser irradiation, which is generally used for plasmon excitation, not only increased the electromagnetic field intensity but also generated heat around the nanostructure, leading to the DNA becoming permanently fixed on the plasmonic substrate. Using fs laser irradiation, on the other hand, the trap-and-release of DNA was achieved by switching the fs laser irradiation on and off. This trap-and-release behavior was clearly observed using a fluorescence microscope. This technique can also be used for manipulating other biomolecules such as nucleic acids, proteins, and polysaccharides, and will prove to be a useful tool in the fabrication of biosensors.
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