Center for Functional Nanomaterials Seminar

One of the main goals of nanotechnology is developing methods for creation of designed nano-scaled systems with ability to control their structures, transformations and dynamic processes. Such full control over the material design will permit achieving the desired functional properties. Approaches based on DNA-driven assembly of nanosystems were recently demonstrated as a powerful route for regulated self-assembly at nanoscale. Metal nanoparticles or quantum dots, functionalized with oligonucleotides are envisioned in this approach to be precisely directed in targeted structures, in bulk, at surfaces or within a cluster. The Watson-Crick recognition between DNA grafted on particle surface allows for programming interparticle interactions with extreme richness and thermodynamical tunability. We extended DNA-assembly methodology for fabrication of dynamically responsive nanoclusters and nanocrystals using a linking particles 'i-motif', a DNA sequence that responds to pH stimulation. DNA double strands were also applied as an interparticle distance controller to self-assemble a series of clusters with core-shell architecture. The core, gold nanoparticle (AuNP) was surrounded by the shell of DNA-attached colloidal quantum dots (QD), forming AuNP-DNA-QD clusters with tunable optical (photoluminescence) responses, which mimics the architecture of light harvesting complex. A novel strategy for assembling 3D nanoparticle clusters was demonstrated: designing a molecular frame with encoded vertices for particles placement. Using a DNA origami octahedron as such frame, we positioned specific particles types at the octahedron vertices, which permitted a fabrication of clusters with different symmetries and particles composition. We applied the combination of cryo-EM technique and single particle method to uncover the structure of the DNA frame and to reveal that nanoparticles are spatially coordinated in the prescribed manner. We also proposed a ne