Progress in controlled assembly of chiral plasmonic nanostructures at Suzhou Nanoscience Institute
Chiral plasma nanostructures have optical activity in the visible light region, and have great potential for application in negative refractive index materials, subwavelength imaging, optical polarization, and high sensitivity molecular characterization and detection, and are currently rapidly developed internationally. Hot spot.
At present, the "bottom-up" self-assembly method has been widely used to construct chiral plasma nanostructures, and the assembly of superstructures mainly uses spherical metal nanomaterials as the building blocks, because spherical metal nanomaterials have no spatial orientation difficulties. It is more convenient to control the spatial configuration of its chiral superstructure. However, the spherical metal nanoparticle chiral superstructure reported today has the characteristics of small particle size and weak near-field coupling of internal plasma, and usually has weaker optical activity.
In the three-dimensional space, non-spherical metal nanomaterials are spatially located, separated, and rotated at the nanoscale resolution, thereby precisely controlling the spatial parameters such as particle spacing, inter-particle angles, and the like in the chiral superstructure, and manufacturing excellent plasma optics. Activity is a great challenge.
Recently, the research team of the Institute of Nanotechnology and Nanobionics of the Chinese Academy of Sciences, Wang Qianbin, successfully used the double-sided DNA origami as a molecular template to successfully assemble the three-dimensional plasma chiral superstructure of gold nanorods. They arranged the same sequence of single-stranded DNA as capture strands on both sides of origami and formed an “X†shape pattern. Two gold nanorods modified with complementary DNA were positioned on both sides of origami and rotated in the direction of the origami plane. The "X" shaped space structure is stacked in the direction of the origami plane in the other direction, and finally assembled into a gold nanorod spiral superstructure.
By designing the angles of the "X"-shaped pattern of the capture chain such as 45° and negative 45°, they constructed the right and left hand gold nanorod spiral superstructures, respectively. Circular dichroism spectroscopy shows that the gold nanorod spiral superstructure exhibits excellent chiral optical properties in the visible light band. The above results were published in the "American Chemical Society" (Xiang Lan, Xuxing Lu, Chenqi Shen, Yonggang Ke, Weihai Ni and Qiangbin Wang*. Journal of the American Chemical Society, 2015, 137, 457-462.).
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