Metallic-Nanostructure-Enhanced Optical Trapping of Flexible Polymer Chains in Aqueous Solution As Revealed by Confocal Fluorescence Microspectroscopy
Metallic-Nanostructure-Enhanced Optical Trapping of Flexible Polymer Chains in Aqueous Solution As Revealed by Confocal Fluorescence Microspectroscopy
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DOI：
10.1021/jp305247a
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发表时间：
2012-06
影响因子：
3.7
通讯作者：
Mariko Toshimitsu;Yuriko Matsumura;T. Shoji;N. Kitamura;Mai Takase;K. Murakoshi;H. Yamauchi;S. Ito;H. Miyasaka;A. Nobuhiro;Y. Mizumoto;H. Ishihara;Yasuyuki Tsuboi
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文献类型：
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作者：
Mariko Toshimitsu;Yuriko Matsumura;T. Shoji;N. Kitamura;Mai Takase;K. Murakoshi;H. Yamauchi;S. Ito;H. Miyasaka;A. Nobuhiro;Y. Mizumoto;H. Ishihara;Yasuyuki Tsuboi
利用显微成像和共聚焦荧光光谱技术研究了柔性聚合物链在金属纳米结构表面的光捕获。一个荧光标记的聚（N-异丙基丙烯酰胺）的目标，是一个代表性的热响应聚合物。在共振等离子体激发时，清楚地观察到聚合物被组装到激发区域中以形成分子组装体。同时，该区域的荧光明显增强，表明该区域的聚合物链数量增加。明显捕获所需的光强度的激发阈值为1 kW/cm 2，这比使用聚焦激光束的常规捕获低104倍。组装体的形貌对激发强度敏感。我们精确地评估了等离子体激发时金属纳米结构周围的温升（ΔT）：ΔT在1 kW/cm 2激发时为10 K。这种温度上升是一个排斥性的雾的起源。
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) was targeted, being a representative thermo-responsive polymer. Upon resonant plasmonic excitation, it was clearly observed that polymers were assembled into the excitation area to form molecular assemblies. Simultaneously, fluorescence from the area was obviously intensified, indicating an increase in the number of polymer chains at the area. The excitation threshold of light intensity that was required for obvious trapping was 1 kW/cm2, which was much lower by a factor of 104 than that for conventional trapping using a focused laser beam. The morphology of the assemblies was sensitive to excitation intensity. We precisely evaluated temperature rise (ΔT) around the metallic nanostructure upon plasmonic excitation: ΔT ≈ 10 K at 1 kW/cm2 excitation. This temperature rise was an origin of a repulsive fo...