Metallic-Nanostructure-Enhanced Optical Trapping of Flexible Polymer Chains in Aqueous Solution As Revealed by Confocal Fluorescence Microspectroscopy

• DOI: 10.1021/jp305247a
• Publication Date: 2012-06-19T22:51:42Z
• Authors: Mariko Toshimitsu; Yuriko Matsumura; Tatsuya Shoji; Noboru Kitamura; Mai Takase; Kei Murakoshi; Hiroaki Yamauchi; Syoji Ito; Hiroshi Miyasaka; Atsushi Nobuhiro; Yoshihiko Mizumoto; Hajime Ishihara; Yasuyuki Tsuboi
• Keywords: 02 engineering and technology; 540; 0210 nano-technology; 543

Optical trapping of flexible polymer chains to a metallic nanostructured surface was explored by microscopic imaging and confocal fluorescence spectroscopy. A fluorescence-labeled poly(N-isopropylacrylamide) targeted, being representative thermo-responsive polymer. Upon resonant plasmonic excitation, it clearly observed that polymers were assembled into the excitation area form molecular assemblies. Simultaneously, from obviously intensified, indicating an increase in number at area. The threshold light intensity required for obvious 1 kW/cm2, which much lower factor 104 than conventional using focused laser beam. morphology assemblies sensitive intensity. We precisely evaluated temperature rise (ΔT) around nanostructure upon excitation: ΔT ≈ 10 K kW/cm2 excitation. This origin repulsive force blocked stable trapping. On basis experimental observations theoretical calculations, we quantitatively plasmon-enhanced thermal (Soret effect). overall mechanisms involved such optical are discussed detail. smooth catch-and-release (manipulation) successfully demonstrated.