Light-induced in situ active tuning of the LSPR of gold nanorods over 90 nm.

We demonstrate an easy and controllable method for light-induced active tuning of the longitudinal surface plasmon resonance (LSPR) of gold nanorods (AuNRs) over ∼94. The red-shift of the LSPR can be controlled by varying the time of exposure to a 532 nm laser. The tuning is achieved by photo-induced dissolution of individual AuNRs by sodium dodecyl sulfate (SDS) under continuous illumination.

Core-shell Au@AuAg nano-peanuts for the catalytic reduction of 4-nitrophenol: critical role of hollow interior and broken shell structure.

Bimetallic hollow core-shell nanoparticles have gained immense attention, especially as a high-performance catalyst due to their large surface area and increased number of uncoordinated atoms. However, the synthesis of an anisotropic hollow structure with large number of uncoordinated atoms and tailored hole size remains elusive. Herein, we report the synthesis of peanut-like core-shell nanostructures consisting of Au nanorods as the core covered by the AuAg alloy shell.

Synthesis of Solution-Stable End-to-End Linked Gold Nanorod Dimers via pH-Dependent Surface Reconfiguration.

End-to-end dimers of gold nanorods are predicted to be excellent substrates for surface-enhanced spectroscopy. However, the synthesis of solution-stable end-to-end dimers remains challenging. We exploit the pH-dependent configurational change of polyelectrolytes to initiate and terminate the gold nanorod assembly formation to produce end-to-end linked dimers in high yield.

modulation of gold nanorod's surface charge drives the growth of end-to-end assemblies from dimers to large networks that enhance single-molecule fluorescence by 10 000-fold.

End-to-end assemblies of anisotropic plasmonic nanostructures with small nanogaps are of great interest as they create strong hot spots for enhancing weak fluorescence and/or scattering of molecules. Here we report the growth of dithiol-linked end-to-end assemblies of gold nanorods from dimers to large networks containing thousands of individual nanorods, directed by tuning of nanorod's surface charge. Surface charge was lowered to initiate the aggregation process but was subsequently increased to achieve slow tip-specific growth over seven days to form end-to-end networks of nanorods, which were stable in solution for over one month.

Synthesis of Complex Nanoparticle Geometries via pH-Controlled Overgrowth of Gold Nanorods.

We show that many complex gold nanostructures such as the water chestnut, dog bone, nanobar, and octahedron, which are not easily accessible via a direct seed-growth synthesis approach, can be prepared via overgrowth of the same gold nanorods by varying pH and Ag concentrations in the growth solution. Overgrown nanostructures' shapes were determined by the rate of gold atom deposition, which is faster at higher pH. In the presence of AgNO, codeposition of gold and silver atoms affects the shapes of overgrown nanostructures, particularly at high pH.