Gold Nanowire Fabrication with Surface-Attached Lipid Nanotube Templates

Abstract

The fabrication of conductive nanostructures is the key technology in semiconductor industry and has gained importance in biology for applications such as biosensors and drug delivery. There is a growing interest in the use of lipid nanotubes (LNTs) as templates in the fabrication of one-dimensional nanostructures such as gold nanowires. The lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) is known to self-assemble into single-wall synthetic LNTs on polyelectrolyte-functionalized surfaces. DOPE is the main component of bacterial cell membranes and its self-assembly into tubes is similar to the tube formation in bacteria. LNT structures have been shown to have biological applications such as in the transport of intercellular organelles and in transmitting electrical signals between cells. We have demonstrated a high-throughput approach to fabricate gold nanowires on surfaces with a LNT template. First, biotin-tagged DOPE LNTs are formed from lipid blocks in inverted hexagonal phase adsorbed on polymer-coated surfaces upon application of shear force. Streptavidin-coated gold nanoparticles were then attached to the biotin-tagged LNTs and gold nanoparticle-encapsulated LNTs were cross-linked by chemical fixation. Samples were dried and treated with oxygen plasma to remove the organic template and connect the particles. The created nanowires were characterized by cryo-transmission electron microscopy, atomic force microscopy and electrical measurements. The method is advantageous because the small size of LNTs enables the fabrication of solid nanostructures with a higher throughput without using expensive electron beam lithography. The approach can further be combined with single LNT patterning with a micromanipulator to create distinct patterns instead of random networks.