Precise Assembly And Optical Properties Of Chiral Gold Nanorod Superstructures Based On DNA Self-assembly

In recent years,plasmonic metal nanostructures with chiral optical response characteristics in the visible light band have attracted more and more attention.The rapid development of DNA nanotechnology has brought many plenty of tools to nanophotonics.DNA nanotechnology,especially DNA origami nanotechnology,has been applied to guide the precise arrangement of plasmonic nanoparticles in space.A series of plasmonic nanostructures with chiral optical properties have been successfully constructed through a bottom-up method.However,the precise dynamic control of these chiral plasmonic structures is still quite challenging.Based on a large number of previous studies,this research utilizes DNA origami to organize anisotropic gold nanoparticles with chiral plasmonic signal.This research mainly includes three relevant parts as follows:First of all,a series of gold nanoparticles of different sizes were synthesized,with uniform particle size and good dispersion,the LSPR of them: 650nm-920 nm.The rapid DNA modification and purification method was tried to complete the DNA functionalization.This method is faster and has better stability compared to traditional methods.A flat triangular DNA origami is designed for easily assembly.Using the principle of base pairing,it can be paired in a variety of ways.According to Characterization experiments,we can ensure that triangular DNA origamis are prepared successfully with high yield and good distribution.Second,although through top-down electron beam lithography,chiral superstructures can be manufactured.However,due to its limitations,it will be challenging to manufacture more precise structures using traditional top-down methods.We use the DNA origami template,through the ingenious design of the upper and lower layers of DNA origami,using different sizes of gold nanorods as the building blocks,modifying gold nanorods with different DNA sequences,and rapidly assembling the chiral dimer structure,the upper and lower layers of gold rods are at a certain angle,60°.On this basis,the structure of the binary star 12 mers is constructed,and the12 mers of different sizes allow to achieve adjustable wavelength ranges.And the core-shell structures of gold nanorods 12 mers are prepared by trying different experimental conditions as an extension.Finally,the 12 mers further amplifies the CD signal,calculating larger optical asymmetries due to the overlaid coupling mode.The g factor of chiral superstructures is up to 0.06.Insightful understanding of size-dependent optical signatures and precise regulation is critical for developing applications of LSPR.We study the scattering spectra by using dark-field microscopy.Moreover,we study the Circularly Polarized Luminescence（CPL）of the assemblies.The results are conformed to general rules and exhibit strong emission intensity.