Fabrication of High Aspect Ratio Gold Nanowires within the Microtubule Lumen.

Gold nanowires have great potential use as interconnects in electronic, photonic, and optoelectronic devices. To date, there are various fabrication strategies for gold nanowires, each one associated with particular drawbacks as they utilize high temperatures, toxic chemicals, or expensive compounds to produce nanowires of suboptimal quality. Inspired by nanowire fabrication strategies that used higher-order biopolymer structures as molds for electroless deposition of gold, we here report a strategy for the growth of gold nanowires from seed nanoparticles within the lumen of microtubules. Luminal targeting of seed particles occurs through covalently linked Fab fragments of an antibody recognizing the acetylated lysine 40 on the luminal side of α-tubulin. Gold nanowires grown by electroless deposition within the microtubule lumen exhibit a homogeneous morphology and high aspect ratios with a mean diameter of 20 nm. Our approach is fast, simple, and inexpensive and does not require toxic chemicals or other harsh conditions.

Triangulated Wireframe Structures Assembled Using Single-Stranded DNA Tiles.

The field of structural DNA nanotechnology offers a wide range of design strategies with which to build structures with a desired aspect ratio, size, and shape. Compared with traditional close-packed DNA structures, triangulated wireframe structures require less material per surface or volume unit and improve the stability in biologically relevant conditions due to the reduced electrostatic repulsion. Herein, we expand the design space of the DNA single-stranded tile method to cover a range of anisotropic, finite, triangulated wireframe structures as well as a number of one-dimensional crystalline assemblies. These structures are composed of six-arm junctions with a single double helix as connecting edges that assemble in physiologically relevant salinities. For a reliable folding of the structures, single-stranded spacers 2-4 nucleotides long have to be introduced in the junction connecting neighboring arms. Coarse-grained molecular dynamics simulations using the oxDNA model suggests that the spacers prevent the stacking of DNA helices, thereby facilitating the assembly of planar geometries.