DNA Origami-encoded Integration Of Heterostructures

The controllable integration of dissimilar structures in range of nanometer scale is a long-term goal of chemistry and material science community;it will lay the material foundation for modern electronics and optoelectronics.However,typical material integration strategies are generally limited to materials with strict structure matching and processing compatibility.As a new advance,van der Waals heterostructure integration offers bond-free integration strategies for improving yield,processability and scalability.However,this method is limited to two-dimensional materials with atomic-level uniformity.Under this context,materials design assisted by DNA nanostructures has attracted much attention due to the high programmability,mass production scalability and spatial precision of DNA nanostructures.The structural DNA nanotechnology provides a universal platform for precision assembly of heterostructures.Various homogeneous materials can be organized by DNA origami so far,including various metal particles,polymers,inorganic oxides,carbon nanotubes and so on.Among them,DNA based metal and silica homostructure fabrication are of practical interest for creating nano-electronics and optoelectronics,which provide necessary conductor,semi-conductor,and insulator substance for such devices.However,to achieve functional devices,the integration of dissimilar structuress on DNA nanostructures is a remaining challenging in the field of structural DNA nanotechnology.If one attempts to realize dissimilar structuress growth such as silica-metal heterostructures on predefined sites of an identical DNA origami template,mutual interference of redox and condensation reaction must be avoided,which is much more complicated than previously reported homostructure fabrication.To solve the above-mentioned difficulties,this study focused on heterogeneous integration of dissimilar structuress encoded by DNA nanostructures.The main research content is as follows:（1）DNA origami-encoded site-specific homogeneous reaction.We started with site-specific homogeneous reaction prior to heterogeneous integration.The DNA-metal（Au/Ag）and DNA-silica structures were first fabricated.The typical triangular DNA origami served as the model and was logically divided into three reaction areas,in which was reserved for silicification,metallization,and as blank surface.The different protruding double-stranded DNA（ds DNA）strands design on the DNA origami template leads to different binding energies between silica/metal clusters and DNA.The results showed that by adjusting the density and length of the protruding ds DNA strands,as well as the reaction conditions,the silicification process was restricted exclusively in the predesigned area without disturbing the rest part of the origami surface.Meanwhile,Au and Ag metallization reaction was restricted in the predesigned area as well.The effect of protruding DNA strands density and length in both silicification and metallization systems were exclusively verified.The results showed that the thickness of the deposited silica,Au,and Ag cluster can be tuned by the density and length design of the protruding ds DNA strands,which enables the precise regulation of the site-specific homogeneous reaction.（2）DNA origami-encoded site-specific heterogeneous reaction.Then we aim to integrate silicification and metallization process on one origami template to fabricate silica-metal（Au/Ag）heterostructure models.Rational design of the spatial arrangements of the protruding ds DNA strands enabled effective differentiation of the binding energies between silica/metal clusters and protruding ds DNA strands/DNA.The results showed that by adjusting the density and length of the protruding ds DNA strands,two types of Si O₂-Au and Si O₂-Ag heterostructures were fabricated.They were named type-I and type-II heterostructures,respectively.For type-I heterostructures,silica and metal（Au/Ag）clusters were separately deposited on distinct area of the triangular origami template to form“V-”shape Si O₂-Au and Si O₂-Ag heterostructures.For type-II heterostructures,metal（Au/Ag）clusters were first restricted in a specific area on origami templates.Silica layer then completely covered the whole DNA origami template to form Si O₂-Au and Si O₂-Ag heterostructures.Thus,we demonstrate the integration of silica-gold and silica-silver heterostructures with high site addressability.（3）Theoretical studies on dissimilar structure integration encoded by DNA origami.We finally carried out full atomic molecular dynamics（MD）simulation to further understand the early nucleation and growth mechanism of dissimilar structures on DNA origami template.The theoretical studies revealed distinctive mechanisms for the binding and aggregation of silica and metal clusters on protruding ds DNA strands that are prescribed on the DNA origami template.We found that the calculated maximum binding energy of gold clusters and protruding ds DNA strands is one magnitude higher than that of silica clusters,resulting in effective growth of silica-gold heterostructures without mutual interference.In summary,the study showed that by programming the densities and lengths of protruding ds DNA strands on DNA origami,silica and metal materials can be independently deposited at their predefined areas with a high vertical precision of 2 nm.In particular,the theoretical studies showed that the binding energy differences of silica/metal clusters and DNA molecules at different sites based on rational design of DNA templates underlies the accessibilities of dissimilar structure fabrication on DNA origami.This work expands the application boundary of structural DNA nanotechnology in the field of material chemistry and deepens our understanding of the chemical microenvironment at the surface of DNA nanostructures.