DNA Origami Welding Sticks Enable Dielectrophoretic Growth of Gold Nanowires

Electric fields can gather metal nanoparticles between electrodes, but turning them into continuous conductors at a chosen site remains difficult: at kilohertz frequencies free particles grow branched aggregates, and at the megahertz frequencies that favor straight wires, free DNA-coated particles were not collected at all under our conditions. Here, DNA origami tubes holding three 13 nm gold nanoparticles serve as carriers that deliver gold to the gap and then give it up to form wires. The tubes roll from a 72 × 89 nm sheet around particles bound by A20:T20 tethers and carry three particles, 25 nm apart. Three-dimensional field calculations show that at this spacing the peak field is only 1.14 times that of an isolated particle, so the scaffold creates no hot spots. At 1.2 MHz, hybrids form particle lines between Ti/Au tips where free particles leave no wire, and fronts grow from one or both tips to bridge 0.35–2.2 µm gaps. The products are polycrystalline gold with rounded grains up to about 60 nm; 13 of 17 structures conduct, with linear current–voltage curves and length-independent two-terminal resistances of 60–360 Ω. A circuit model accounts for this: after bridging, about 40 mA flows, and Joule heating melts any constriction that drops more than about 0.4 V, so growth should end when the wire is a few ohms and the leads dominate the measured value. DNA origami thus serves as a field-trappable carrier and consumable feedstock for bottom-up interconnects.