Directed Assembly of Gold Nanorods by Terminal‐Base Pairing of Surface‐Grafted DNA

Abstract

Directed assemblies of anisotropic metal nanoparticles exhibit attractive physical and chemical properties. However, an effective methodology to prepare differently directed assemblies from the same anisotropic nanoparticles is not yet available. Gold nanorods (AuNRs) region-selectively modified with different DNA strands can form side-by-side (SBS) and end-to-end (ETE) assemblies in a non-crosslinking manner. When the complementary DNA is hybridized to the surface-bound DNA, stacking interaction between the blunt ends takes place in the designated regions. Such AuNRs assemble into highly ordered structures, assisted by capillary forces emerging on the substrate surface. Moreover, insertion of a mercury(II)-mediated thymine-thymine base pair into the periphery of the DNA layer allows selective formation of the SBS or ETE assemblies from the strictly identical AuNRs with or without mercury(II).

Reversible Shrinkage of DNA‐Functionalized Gold Nanoparticle Assemblies Revealed by Surface Plasmon Resonance

“…Instead of controlling the salt concentration, temperature served as the variable to transform the dimer structure. In a recent work, we succeeded in controlling the size of non‐crosslinked assembly of DNA‐functionalized gold nanorods by altering the temperature . Figure D shows the SPR peak position of the dimer at 36 °C and 39 °C.…”

“…In a recent work, we succeeded in controlling the size of non-crosslinked assembly of DNA-functionalized gold nanorods by altering the temperature. [15] Figure 2D shows the SPR peak position of the dimer at 36 C and 39 C. This temperature range was carefully selected because no difference in the SPR band was observed at the temperature higher than 39 C and because aggregation of the dimers inevitably occurred at the temperature lower than 36 C. It should be noted that the melting temperature values of the duplex between the cover DNA and the complementary DNA and the duplex between the anchor DNA and the binding site of the template DNA were calculated using the HyTher program [16] to be 57.9 C and 52.7 C, respectively, both of which were sufficiently higher than 39 C. Initially, an aqueous dispersion of the 15 nm-AuNP dimers was prepared at 39 C in the presence of 0.35 M NaCl. The SPR band appeared at 524.5 nm.…”

Two‐Step Assembly of Thermoresponsive Gold Nanorods Coated with a Single Kind of Ligand

“…From 25 to 30 °C, the L‐LSPR was shifted to a shorter wavelength and merged with the T‐LSPR. It has been reported that the blue shift in the L‐LSPR and the concurrent red shift in T‐LSPR occur on the formation of side‐by‐side assemblies . Therefore, the observed spectrum at 30 °C indicates the formation of a side‐by‐side assembly.…”

“…It has been reported that the blue shift in the L-LSPR and the concurrent red shift in T-LSPR occur on the formation of side-by-side assemblies. [57][58][59][60][61][62] Therefore, the observed spectrum at 30 °C indicates the formation of a side-by-side assembly. The extinction peaks plotted against temperature upon heating also clearly show that side-by-side assembly occurred between 25 and 30 °C (Figure 2c).…”

Regioselective DNA Modification and Directed Self-Assembly of Triangular Gold Nanoplates

“…In addition to applications in sensors and gene diagnostics [16,17], non-crosslinking aggregation showed its potential for the ordered assembly of gold nanorods (AuNRs) by controlling surface modification with DNA [18]. We demonstrated that the AuNRs, regioselectively modified with dsDNA, formed orientation-controlled assemblies in a non-crosslinking fashion.…”