DNA Brush-Directed Vertical Alignment of Extensive Gold Nanorod Arrays with Controlled Density

Abstract

Control over the orientation of metal nanorods is important for both fundamental and applied research. We show that gold nanorods (GNRs) can be aligned in a single direction by adsorbing positively charged GNRs onto a double-strand DNA-grafted substrate through electrostatic interaction. The ordered structure can be optimized by controlling the density of the positive charges on the surface of the GNRs. We found, in agreement with the results of theoretical simulation, that the resultant structure exhibits plasmonic properties that are dependent on the GNR orientation relative to the direction of an oscillating electric field. Our approach provides new insights into the polymer-assisted self-assembly of rod-shaped nanoparticles utilizing electrostatic interactions.

Reversible changes in the orientation of gold nanorod arrays on polymer brushes

“…In our previous study, we developed a preparation method for vertically aligned GNR arrays using polymer brushes as a template. 41,42 As the polymer brushes are so matrices, it is expected that the GNR orientation can be actively tuned through some kind of stimulation. In those reports, we found that GNRs formed vertically aligned arrays when mildly cationized GNRs, which were modied with 20% cationic and 80% nonionic ligands, were attached on negatively charged polymer (DNA) brushes via moderate electrostatic interactions.…”

“…1b). 41 A p-polarized light-specic L-LSPR peak can be observed around 640 nm (highlighted in yellow). This blue-shi Scheme 1 Preparation of vertical gold nanorod arrays and their pHresponsive changes in orientation.…”

Micro-liquid enclosure array and its semi-automated assembling system for x-ray free-electron laser diffractive imaging of samples in solution

“…Measured dried STEM images, however, contained some self-assemblies with a certain degree of deformation. More generally, self-assemblies in solutions are fragile and undergo large structural changes through the drying process or the interaction with the substrate, 41,42 which may cause the loss of their functions. Imaging of intact structures and dynamics in solution is thus important.…”

Strategy for Finely Aligned Gold Nanorod Arrays Using Polymer Brushes as a Template

“…We recently reported that positively charged gold nanorods (GNRs) could be immobilized onto double-stranded (ds) DNA brushes perpendicular to the substrate via weak electrostatic interactions when the cationic charge density is low. 41 On the other hand, when highly charged GNRs were used, the GNRs showed different surface plasmon spectra, indicating that the GNRs did not align vertically. Importantly, this system enables us to prepare vertically aligned gold nanorod arrays with a controlled density via a simple bottomup process.…”