Self-assembled nanogaps via seed-mediated growth of end-to-end linked gold nanorods

TY - JOUR

T1 - Self-assembled nanogaps via seed-mediated growth of end-to-end linked gold nanorods

AU - Jain, Titoo

AU - Westerlund, Axel Rune Fredrik

AU - Johnson, Erik

AU - Moth-Poulsen, Kasper

AU - Bjørnholm, Thomas

PY - 2009

Y1 - 2009

N2 - Gold nanorods (AuNRs) are of interest for a wide range of applications, ranging from imaging to molecular electronics, and they have been studied extensively for the past decade. An important issue in AuNR applications is the ability to self-assemble the rods in predictable structures on the nanoscale. We here present a new way to end-to-end link AuNRs with a single or few linker molecules. Whereas methods reported in the literature so far rely on modification of the AuNRs after the synthesis, we here dimerize gold nanoparticle seeds with a water-soluble dithiol-functionalized polyethylene glycol linker and expose the linked seeds to growth conditions identical to the synthesis of unlinked AuNRs. Doing so, we obtain a large fraction of end-to-end linked rods, and transmission electron microscopy provides evidence of a 1-2 nm wide gap between the AuNRs. Flow linear dichroism demonstrates that a large fraction of the rods are flexible around the hinging molecule in solution, as expected for a molecularly linked nanogap. By using excess of gold nanoparticles relative to the linking dithiol molecule, this method can provide a high probability that a single molecule is connecting the two rods. In essence, our methods hence demonstrate the fabrication of a nanostructure with a molecule connected to two nanoelectrodes by bottom-up chemical assembly.

AB - Gold nanorods (AuNRs) are of interest for a wide range of applications, ranging from imaging to molecular electronics, and they have been studied extensively for the past decade. An important issue in AuNR applications is the ability to self-assemble the rods in predictable structures on the nanoscale. We here present a new way to end-to-end link AuNRs with a single or few linker molecules. Whereas methods reported in the literature so far rely on modification of the AuNRs after the synthesis, we here dimerize gold nanoparticle seeds with a water-soluble dithiol-functionalized polyethylene glycol linker and expose the linked seeds to growth conditions identical to the synthesis of unlinked AuNRs. Doing so, we obtain a large fraction of end-to-end linked rods, and transmission electron microscopy provides evidence of a 1-2 nm wide gap between the AuNRs. Flow linear dichroism demonstrates that a large fraction of the rods are flexible around the hinging molecule in solution, as expected for a molecularly linked nanogap. By using excess of gold nanoparticles relative to the linking dithiol molecule, this method can provide a high probability that a single molecule is connecting the two rods. In essence, our methods hence demonstrate the fabrication of a nanostructure with a molecule connected to two nanoelectrodes by bottom-up chemical assembly.

U2 - 10.1021/nn900066w

DO - 10.1021/nn900066w

M3 - Journal article

C2 - 19284731

SN - 1936-0851

VL - 3

SP - 828

EP - 834

JO - ACS Nano

JF - ACS Nano

IS - 4

ER -