DNA Mold‐Based Fabrication of Palladium Nanostructures

Abstract

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.

Heavy Metal Stabilization of DNA Origami Nanostructures

“…At 90 °C the reaction was completed within 30 s. At this temperature, in addition to the rod-like Pd structures that grew inside the nanotube channels, some metal grains started to grow through the nanotube walls (Figure S47) in contrast to the lower temperatures. This is in agreement with our previous findings on the growth of Au and Pd, which suggested that the soft DNA walls best guide the growth of metal nanostructures at reduced reaction rates.…”

“…4−6 A major advantage of this technique is the high assembly yield and the easy functionalization of the DNA structures with chemical groups, 7,8 biomolecules, 9−13 and inorganic nanoparticles. 14−16 In particular, such functionalized DNA origami nanostructures were used to build nanoelectronic components of noble metals like gold, 17−19 silver, 20,21 and palladium, 22,23 less noble metals like copper, 20,24,25 or semiconducting materials. 26−29 Furthermore, the DNA origami technique was used to build nanoscale lithography masks to improve the spatial resolution in the fabrication of nanoelectronic and nanophotonic devices.…”

“…To demonstrate the benefit of our Pd stabilization protocol for DNA origami nanostructure applications, we tested whether we can make use of the heat stability of the modified DNA nanotubes. To these end, we employed our stabilized tube trimer structures in a DNA mold-based palladium nanoparticle (PdNP) growth procedure that we established previously . Single PdNP seeds were attached in the centers of the trimer structures, which were subsequently stabilized with [PdCl 4 ] 2– .…”

“…We are confident that the heavy-metal-based stabilization of DNA origami structures has great potential in the DNA origami-based bottom-up fabrication of electric circuits. So far, only noble metals like gold, − silver, , palladium, , and the semi-noble-metal copper , have been grown on DNA origami templates. However, to recreate all aspects of electric circuits, the deposition of less noble materials, e.g., nickel, would be required.…”

DNA Origami-Based Letterpress Printing of Gold Nanostructures with Predesigned Morphologies

“…Then, these PdNPs were grown by the chemical reduction method to synthesize rodlike palladium structures with a diameter of 20–35 nm. Finally, linear palladium nanostructures with a controllable length and a controllable pattern were fabricated by connecting DNA origami nanotubes by thermal annealing . Although this method overcomes environmental, distance, and stability issues, it proved challenging to control multiple reaction parameters, and this method cannot be used to synthesize diverse metallic nanostructures.…”