We introduce a new concept for the solution-based fabrication of conductive gold nanowires using DNA templates. To this end, we employ DNA nanomolds, inside which electroless gold deposition is initiated by site-specific attached seeds. Using programmable interfaces, individual molds self-assemble into micrometer-long mold superstructures. During subsequent internal gold deposition, the mold walls constrain the metal growth, such that highly homogeneous nanowires with 20-30 nm diameters are obtained. Wire contacting using electron-beam lithography and electrical conductance characterization at temperatures between 4.2 K and room temperature demonstrate that metallic conducting wires were produced, although for part of the wires, the conductance is limited by boundaries between gold grains. Using different mold designs, our synthesis scheme will, in the future, allow the fabrication of complex metal structures with programmable shapes.

Recently introduced DNA nanomolds allow the shape-controlled growth of metallic nanoparticles. Here we demonstrate that this approach can be used to fabricate longer linear metal nanostructures of controlled lengths and patterns. To this end, we establish a set of different interfaces that enable mold interactions with high affinity and specificity. These interfaces enable and control the modular assembly of mold monomers into larger mold superstructure with programmable dimension in which each mold monomer remains uniquely addressable. Preloading the molds with nanoparticle seeds subsequently allows the growth of linear gold nanostructures whose lengths are controlled by the DNA structure. Exploiting the addressability of individual mold monomers furthermore allows achievement of site-specific metallization, that is, to create defined metal patterns. We think that the introduced approach provides a useful basis to fabricate nanomaterials with complex shapes and material composition in a fully programmable and modular fashion.

Advances in DNA nanotechnology allow the design and fabrication of highly complex DNA structures, uisng specific programmable interactions between smaller nucleic acid building blocks. To convey this concept to the fabrication of metallic nanoparticles, an assembly platform is developed based on a few basic DNA structures that can serve as molds. Programming specific interactions between these elements allows the assembly of mold superstructures with a range of different geometries. Subsequent seeded growth of gold within the mold cavities enables the synthesis of complex metal structures including tightly DNA‐caged particles, rolling‐pin‐ and dumbbell‐shaped particles, as well as T‐shaped and loop particles with high continuity. The method further supports the formation of higher‐order assemblies of the obtained metal geometries. Based on electrical and optical characterizations, it is expected that the developed platform is a valuable tool for a self‐assembly‐based fabrication of nanoelectronic and nanooptic devices.

Higher‐order superstructures of individual DNA origami building blocks are frequently used in DNA nanotechnology in order to increase the structure dimensions and complexity. Here, a purification method is presented to specifically enrich a fully assembled superstructure out of an excess of substructures. The approach is based on pull‐down reactions with magnetic beads, where superstructures are captured via an anchor strand on a specific terminus and then become separated from terminus‐free structures. By carrying out several pull‐down reactions sequentially on different termini, the full superstructures that possess all termini become finally enriched. The approach is demonstrated by purifying linear origami superstructures with up to nine monomers by two‐sided pull‐down reactions and a T‐shaped superstructure in a three‐sided pull‐down reaction. In all cases, high recovery yields and purities are obtained. A crucial prerequisite for the sequential pull‐down scheme is the establishment of highly specific, orthogonal sequence sets for capture, and anchor strands. It is expected that the introduced approach provides a useful and universal method to purify complex DNA origami superstructures with high specificity and yield and this way allows the massive parallel fabrication of nanostructures at high homogeneity.

an optimized methodology was a careful scanning of various reaction parameters to gain better control over the gold growth conditions and the associated reaction kinetics.

Recent progress in DNA nanotechnology allows the fabrication of 3D structures that can be loaded with a large variety of molecular cargos and even be responsive to external stimuli. This makes the use of DNA nanostructures a promising approach for applications in nanomedicine and drug delivery. However, their low stability in the extra-and intracellular environment as well as low cellular uptake rates and release rates from endosomes into the cytoplasm hamper the efficient and targeted use of DNA nanostructures in medical applications. Here, such major obstacles are overcome by integrating DNA origami nanostructures into superordinated layer-by-layer based microparticles made from biopolymers. The modular assembly of the polymer layer allows a high-density incorporation of the DNA structures at different depth. This enables controllable protection of the DNA nanostructures over extended durations in a broad range of extra-and intracellular conditions without compromising the cell viability. Furthermore, by producing protein-complexed DNA nanostructures it is demonstrated that molecular cargo can be conveniently integrated into the developed hybrid system. This work provides the basis for a new multistage carrier system allowing for an efficient and protected transport of active agents inside responsive DNA nanostructures.

Within the field of DNA nanotechnology, numerous methods were developed to produce complex two- and three-dimensional DNA nanostructures for many different emerging applications. These structures typically suffer from a low...

DNA origami molds allow a shape‐controlled growth of metallic nanoparticles. So far, this approach is limited to gold and silver. Here, the fabrication of linear palladium nanostructures with controlled lengths and patterns is demonstrated. To obtain nucleation centers for a seeded growth, a synthesis procedure of palladium nanoparticles (PdNPs) using Bis(p‐sulfonatophenyl)phenylphosphine (BSPP) both as reductant and stabilizer is developed to establish an efficient functionalization protocol of the particles with single‐stranded DNA. Attaching the functionalized particles to complementary DNA strands inside DNA mold cavities supports subsequently a highly specific seeded palladium deposition. This provides rod‐like PdNPs with diameters of 20–35 nm of grainy morphology. Using an annealing procedure and a post‐reduction step with hydrogen, homogeneous palladium nanostructures can be obtained. With the adaptation of the procedure to palladium the capabilities of the mold‐based tool‐box are expanded. In the future, this may allow a facile adaptation of the mold approach to less noble metals including magnetic materials such as Ni and Co.