Proc. SPIE 10712, doi: 10.1117/12.2319571

  • “Optical trapping of gold and semiconductor nanoparticles at oil-water interfaces with a focused near-infrared laser beam.”
  • Tatsuya Shoji, Shota Naka, Seiya Koyama, Tatsuya Kameyama, Tsukasa Torimoto, Yasuyuki Tsuboi

A tightly focused laser beam exerts optical force on nanoparticles dispersed in an aqueous solution, leading to an optical trapping of them at the focal point. Recently, we have developed plasmonic optical tweezers for soft nano-matters such as DNA, thermoresponsive polymer chains, and dye aggregates. We observed the interested trapping behaviors of the soft nanomaterials on such liquid-solid interfaces. Our attention is paid to such optical trapping of them on interfaces because optical force strongly depends on the dielectric constant of the surrounding medium. In the present study, we demonstrated that optical trapping of quantum dots and octahedral gold nanocrystals at water-oil interface. Dark-field microscopy was a powerful tool to observe the trapping behaviors of the gold nanoparticles, while fluorescence microscopy was used for the observations of the quantum dots.