(80a) Metallization of DNA Origami to Form Thin, Electrically Conductive Nanowires

Bottom-up nanotechnology, which enables construction of complex structures from molecular building blocks, is seen as a promising technology to develop future generations of electronic devices. The bottom-up approach takes advantage of molecular self-assembly to create useful architectures of nanometer dimensions. DNA, with its small size, functional groups and complementary base pairs, is a powerful template for nanodevice fabrication via bottom-up assembly. Recent advances in the field of “DNA origami” have enabled fabrication of nanostructures by folding single-stranded DNA into a variety of 2- and 3-D shapes. However, electrically conductive structures are required for electronic applications.

In this study, we report the fabrication of electrically conductive DNA origami-templated nanowires with the use of gold nanorods (Au NR’s) as a step towards DNA nanodevices.  Our process begins with the seeding step where Au NR’s electrostatically bind to the DNA origami backbone. The seeds are then connected by electroless deposition of gold to make continuous wires. The use of nanorods as seeds provides two key advantages over previous work with particulate seeds.  First, the surfactant-enabled anisotropic growth used to initially fabricate the nanorods appears to persist through the electroless plating process on the DNA template. This permits improved control of the width of the final metallized structure since growth in the axial direction is preferred. The average final width of our Au-metallized DNA wires was 11.5 nm (n=30) with a standard deviation of 2.1 nm. We were able to obtain a 60% yield of continuous ~400 nm long DNA wires. In doing so, gaps between seed particles ranging from 10.6 nm on average to as wide as 25 nm were successfully filled. The second advantage of nanorods is the reduction in the number of connection points between seed particles by a factor of three relative to that observed for 5 nm seed particles. The reduced number of connection points is expected to increase the conductivity of the wires. Electrical characterization of the DNA wires is underway and complete current/voltage measurements will be presented.

In summary, we have demonstrated a metallization process to fabricate thin, high aspect ratio, conductive wires on DNA-origami templates with the use of Au NR’s and electroless plating. Continuing efforts seek to use local functionalization to enable site-specific metallization of DNA-origami templates with Au NR’s. The thin nanowires produced in this study will be interfaced with appropriate semiconducting elements to help enable fabrication of self-assembled nanoscale electronic circuits.

References: 

1. Uprety, B.; Gates, E. P.; Geng, Y.; Woolley, A. T.; Harb, J. N. Site-Specific Metallization of Multiple Metals on a Single DNA Origami Template. Langmuir 2014, 30, 1134-1141.
2. Gates, E.P.; Jensen, J.K.; Harb, J.N.; Woolley, A.T. Optimizing Gold Nanoparticle Seeding Density on DNA Origami. RSC Advances 2015, 5, 8134-8141.