Study On Induced Chirality And Structural Chirality Of Surface Plasmon Based On DNA Self-assembly

DNA molecule,a kind of biological macromolecule,encodes or stores the main genetic information of organisms by two reverse complementary deoxynucleotide chains according to the strict complementary nature of the base pairs.At the same time,because of its sequence programmability and inherent chiral characterization,it has always been one of the common materials in the field of chiral self-assembly.The construction of micro chiral systems mediated by DNA molecules has broad application prospects in advanced fields,such as asymmetric catalysis,chiral sensors with detection limit at the single molecule level,plasma optoelectronic devices,etc.In addition,the basic research on the optical properties and mechanisms of the micro chiral system will also help us to deeply understand the interaction between light and matter at the nano-scale.In this paper,several self-assembled hybrid systems based on DNA materials were constructed,and the expression of chirality at the micro-scale was discussed from the two perspectives of induced chirality and structural chirality,so as to deepen our understanding of the basic property of chirality and lay a foundation for future practical applications.The main work of this paper is described as follows:(1)Several colloidal gold particles were synthesized in high yield,and DNA with specific sequences was modified on their surfaces,then purified and recovered by agarose gel electrophoresis.Subsequently,K21 dye was added to these colloidal gold particles solutions to construct several different organic-inorganic hybrid systems,and CD measurement was measured by Circular Dichroic spectrometer.Due to the close coupling between the surface plasmon of colloidal gold particles and the exciton of K21 dye molecule,this new hybrid system will produce a new induced CD signal at the resonant wavelength of colloidal gold particles plasmon.Through comparison,we found that the size and shape of colloidal gold particles and the concentration of K21 dye are two important factors affecting the induced chirality in the organic-inorganic hybrid system.(2)Based on DNA self-assembly technology,DNA rod-origami and DNA cavity-origami with different geometric shapes are designed and assembled.Through the layered assembly strategy,two kinds of DNA origami are regarded as assembly units to further construct three kinds of DNA origami secondary structures by connecting their sticky ends,whose size are both more than 100 nm.Once again,two kinds of DNA origami secondary structures are regarded as assembly units.By adding a group of connecting DNA strands with specific sequences,the same DNA origami secondary structures are connected with each other and extend in one-dimensional direction.Finally,two kinds of DNA origami tertiary structure platforms with hundreds of nanometers are successfully assembled.In addition,colloidal gold particles are successfully assembled and arranged at the specific position of DNA origami to construct a helical superstructure with obvious structural chirality.