Jiangsu Key Laboratory of Thin Films, School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006, China.
CAS Key Laboratory of Nano-Bio Interface, Suzhou Key Laboratory of Functional Molecular Imaging Technology, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
Nano Lett. 2023 Jun 14;23(11):5180-5186. doi: 10.1021/acs.nanolett.3c01159. Epub 2023 May 24.
Active plasmonic metamolecules under microscopic observation are promising for optical reporters in single molecule sensing applications. While self-assembled reconfigurable chiral plasmonic metamolecules can be conveniently engineered with sensing functionalities, their observation is usually based on ensemble measurements, where the chiroptical response of enantiomers tend to cancel each other in ensemble circular dichroism. Herein, we demonstrate microscopic observation of enantiomeric switching of individual active DNA origami-assembled plasmonic metamolecules. The metamolecules are immobilized on a glass substrate in a microfluidic chamber, in which the plasmonic metamolecule can maintain their activities upon certain local stimuli as in solution. In circular differential scattering, two enantiomeric states controlled by the strand-displacement reaction display opposite spectral signals to each other, representing successful enantiomeric switching of the chirality. Moreover, in a close-to-racemic mixture of chiral metamolecules controlled by pH-sensitive strands, the coexistence of enantiomeric individuals, which is concealed in ensemble measurements, is clearly identified.
在微观观察下，活性等离子体超分子结构在单分子传感应用中的光学报告器中具有广阔的应用前景。虽然自组装的可重构手性等离子体超分子结构可以方便地设计出具有传感功能的结构，但它们的观察通常基于集体测量，其中对映体的圆二色性响应在集体圆二色性中往往相互抵消。在这里，我们展示了对单个活性 DNA 折纸组装的等离子体超分子结构的对映体转换的微观观察。超分子结构被固定在微流控室的玻璃基底上，其中在溶液中存在的某些局部刺激下，等离子体超分子结构可以保持其活性。在圆差分散射中，由链置换反应控制的两种对映体状态相互呈现相反的光谱信号，代表了手性的成功对映体转换。此外，在由 pH 敏感链控制的接近外消旋的手性超分子混合物中，在集体测量中被掩盖的对映体个体的共存被清晰地识别出来。
