Framework Nucleic Acid-Directed Assembly Of Nanoplasmons And Their Optical Properties

In recent years,due to the significantly enhanced electromagnetic field in the nanoparticle gap,the so-called "hot spot" effect,nanoplasmons exhibit some unique optical properties,such as the single-molecule surface-enhanced Raman scattering(SM-SERS)effect and attracted much attention.In the past few decades,the main methods for constructing nano-plasmonic materials include electron beam etching,photolithography,and colloidal assembly.However,these traditional top-down nanoscale manufacturing technologies are not only complicated but also costly.More importantly,it is still challenging to achieve the goal of accurately arranging nanoparticles or placing a single Raman active molecule in a hot spot to obtain a reliable single-molecule Raman signal.Bottom-up DNA nanotechnology,especially the emergence of DNA origami with site addressability and sequence programmability,is expected to completely solve the above problems.The inherent sequence programmability of DNA is used to precisely arrange gold nanoparticles to form high-yield metal nanostructures,and finally realize the design,synthesis and adjustment of plasmonic structures with nano-gap in a high-precision and reproducible manner to obtain high reliable and quantifiable plasmonic signal.In this paper,a series of researches have been carried out based on the assembly of DNA origami and Aunanoparticles(AuNPs).For example,the detection of single-molecule surface enhanced Raman scattering signals has been realized by constructing nano-plasmonic structures;self-assembly of the superstructure through the specific connection of modular units;preliminary explorations have also been made on the self-assembly of dynamic structure.The specific results are as follows:1.Based on DNA origami technology,the extended capture sites from the origami were designed,and then self-assembled with specifically modified AuNCs to form five kinds of nanoplasmons.Then we ultilized scanning electron microscope(SEM),dark field microscope(DFM)and Raman colocalization technology to detect the single particle surface-enhanced Raman scattering signals of five AuNC-nanostructures,and realized the detection of single-molecule SERS signals with the help of two heterogeneous polymer structures.2.Based on the research about the polymeric structures in the previous chapter,in this chapter,we controlled the formation of anisotropy and selective binding of heterogeneous DNA nanostructures and used highly adaptive interactions to effectively connect the particles in the module to form seven AuNC-high-level structures with preset shapes.This strategy overcomes the problem of origami size limitations,and at the same time opens up a new path for the super assembly of AuNPs.3.On the basis of the research about the self-assembly of DNA origami/AuNPs static system in the above two chapters,the self-assembly of dynamic structure based on DNA origami is further explored in this chapter.We firstly verified the hybrid chain reaction in one-dimensional solution and then used hybrid chain reaction to drive streptavidin to make linear motion on two-dimensional rectangular origami.Finally,three-dimensional circular DNA origami and hybrid chain reaction were combined to construct a dynamic DNA nano self-assembly system,which also preliminarily proving the possibility of relying on DNA hybridization energy to drive the movement of nano-objects.