Establishing precise control over the shape and the interactions of the microscopic building blocks is essential for design of macroscopic soft materials with novel structural, optical and mechanical properties. Here, we demonstrate robust assembly of DNA origami filaments into cholesteric liquid crystals, one-dimensional supramolecular twisted ribbons and two-dimensional colloidal membranes. The exquisite control afforded by the DNA origami technology establishes a quantitative relationship between the microscopic filament structure and the macroscopic cholesteric pitch. Furthermore, it also enables robust assembly of one-dimensional twisted ribbons, which behave as effective supramolecular polymers whose structure and elastic properties can be precisely tuned by controlling the geometry of the elemental building blocks. Our results demonstrate the potential synergy between DNA origami technology and colloidal science, in which the former allows for rapid and robust synthesis of complex particles, and the latter can be used to assemble such particles into bulk materials.

Inclusions dissolved in an anisotropic quasi-2D membrane acquire new types of interactions that can drive assembly of complex structures and patterns. We study colloidal membranes composed of a binary mixture of long and short rods, such that the length ratio of the long to short rods is approximately two. At very low volume fractions, short rods dissolve in the membrane of long rods by strongly anchoring to the membrane polymer interface. At higher fractions, the dissolved short rods phase separate from the background membrane, creating a composite structure comprised of bilayer droplets enriched in short rods that coexist with the background monolayer membrane. These results demonstrate that colloidal membranes serve as a versatile platform for assembly of soft materials, while simultaneously providing new insight into universal membrane-mediated interactions.Introduction: Colloids, proteins and nanoparticles dissolved in bulk isotropic fluids interact by well-studied intermolecular forces that include steric exclusions, electrostatic repulsions, the hydrophobic effect, and van der Waals interactions 1 . In comparison, particles dissolved in anisotropic environments or confined on surfaces or interfaces can acquire more complex interactions and thus exhibit very different behaviors. For example, experiments have revealed exceedingly complex interactions and assembly pathways of colloids or nano-particles dissolved in anisotropic liquid crystals 2-4 or confined on oil-water interfaces 5-9 . Lipid bilayers provide an even more complex environment for self-assembly. Particles dissolved in a lipid bilayer simultaneously experience a liquid crystalline environment due to ordering of the hydrophobic lipid chains 10 , and are confined to a deformable quasi-2D plane, similar to particle-laden interfaces.Consequently, membrane-mediated interactions can drive assembly of exceedingly complex structures [11][12][13][14][15] . However, the nanometer length scale of conventional lipid bilayers makes studies of lipid bilayers challenging. Consequently, our knowledge of membrane-mediated interactions

Inspired by the ability of cell membranes to alter their shape in response to bound particles, we report an experimental study of long, slender nanorods binding to lipid bilayer vesicles and altering the membrane shape. Our work illuminates the role of particle concentration, adhesion strength, and membrane tension in determining the membrane morphology. We combined giant unilamellar vesicles with oppositely charged nanorods, carefully tuning the adhesion strength, membrane tension, and particle concentration. With increasing adhesion strength, the primary behaviors observed were membrane deformation, vesicle−vesicle adhesion, and vesicle rupture. These behaviors were observed in welldefined regions in the parameter space with sharp transitions between them. We observed the deformation of the membrane resulting in tubulation, textured surfaces, and small and large lipid−particle aggregates. These responses are robust and repeatable and provide a new physical understanding of the dependence on the shape, binding affinity, and particle concentration in membrane remodeling. The design principles derived from these experiments may lead to new bioinspired membrane-based materials.

No abstract

No abstract