The self-assembly of nanoscale elements into three-dimensional structures with precise shapes and sizes is important in fields such as nanophotonics, metamaterials and biotechnology. Short molecular linkers have previously been used to create assemblies of nanoparticles, but the approach is limited to small interparticle distances, typically less than 10 nm. Alternatively, DNA origami can precisely organize nanoscale objects over much larger length scales. Here we show that rigid DNA origami scaffolds can be used to assemble metal nanoparticles, quantum dots and organic dyes into hierarchical nanoclusters that have a planet-satellite-type structure. The nanoclusters have a tunable stoichiometry, defined distances of 5-200 nm between components, and controllable overall sizes of up to 500 nm. We also show that the nanoscale components can be positioned along the radial DNA spacers of the nanostructures, which allows short- and long-range interactions between nanoparticles and dyes to be studied in solution. The approach could, in the future, be used to construct efficient energy funnels, complex plasmonic architectures, and porous, nanoengineered scaffolds for catalysis.

We report on the deposition of individual gold nanorods from an optical trap using two different laser wavelengths. Laser light, not being resonant to the plasmon resonances of the nanorods, is used for stable trapping and in situ alignment of individual nanorods. Laser light, being resonant to the transversal mode of the nanorods, is used for depositing nanorods at desired locations. The power and polarization dependence of the process is investigated and discussed in terms of force balances between gradient and scattering forces, plasmonic heating, and rotational diffusion of the nanorods. This two-color approach enables faster printing than its one-color equivalent and provides control over the angular orientation (±16°) and location of the deposited nanorods at the single-nanorod level.

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Designing nanoscale objects with the potential to perform externally-controlled motion in biological environments is one of the most sought-after objectives in nanotechnology. Different types of chemically and physically-powered motors have been prepared at the macro-and microscale. However, the preparation of nanoscale objects with a complex morphology, and the potential for light-driven motion has remained elusive to date. Here, we go a step forward by designing a nanoscale hybrid with a propeller-resembling shape, which can be controlled by focused light under biological conditions. Our hybrid, hereafter 'Au@DNA-origami', consists of a spherical gold nanoparticle with self-assembled, biocompatible, two-dimensional (2D) DNA sheets on its surface. As a first step towards the potential utilization of these nanoscale objects as light-driven assemblies in biological environments, we show that they can be optically trapped, and hence translated and deposited on-demand, and that under realistic trapping conditions the thermally-induced dehybridization of the DNA sheets can be avoided. KeywordsGold nanoparticles; DNA origami; nanoscale hybrids; self-assembly; optical tweezers; optical manipulation; optical heating Externally-powered nanomotors able to perform controlled motion in biological media through the application of an external chemical 1 or physical input (e.g. a magnetic field, 2 light, 3 or ultrasounds 4 ) are envisaged as promising powerful nanomachines. 5,6 Physical triggers are advantageous over chemical ones: (i) the applied input can be turned on and off on-demand, and hence, a higher control over object motion can be achieved; 7 and (ii) they overcome the utilization of toxic chemical fuels, [8][9][10] allowing for the realization of controlled motion in a wider range of environments. 11 Light is one of the most powerful and versatile physical triggers, and of special interest in the context of bio-related applications, since it can be tuned to operate in the NIR (the so-called biological window). To induce light-controlled rotation of a given object some degree of three-dimensional control is required. The focused light of laser tweezers can provide the trapping force needed to hold * Corresponding Authorjesica.rodriguez@physik.uni-muenchen.de (J.R.F.); feldmann@lmu.de (J.F.).Supporting Information. Experimental part; 2D DNA sheet design (DNA origami); gel electrophoresis purification of the 2D DNA sheets; calculated temperature at the surface of a spherical 60 nm Au nanoparticle. This material is available free of charge via the Internet at http://pubs.acs.org. NotesThe authors declare no competing financial interest. 19 to name a few. More complex structures, with a propeller-like shape, and the potential for light-driven rotation to the best of our knowledge have only been reported at the microscale, and prepared in a 'one-by-one' basis via two-photon polymerization strategies with a spatial resolution in the order of several hundred nanometers. 15,20,21 In an effort to fill this gap, her...