Facile Synthesis of Multi‐Branched Gold Nanostructures through a TBAB‐Assisted Route in Aqueous Solution and Their SERS Property

Abstract

Facile synthesis of multi-branched gold nanostructures by using the tetrabutyl ammonium bromide (TBAB) as a capping agent is described. The reaction is carried out in a one-step process at mild temperature. Gold nanostructures with more than six sharp branches ranging from 70 to 130 nm in length are synthesized in high yield. It is proposed that the relative weak adsorption capacity of TBAB leads to the incompletely covered gold surface and the growth of nanoparticles occurs on the uncovered gold surface, and therefore short branches appear consequently. Then positively charged TBAB layers on the gold surfaces prevent the branches from aggregating with each other which stimulates the branch growth. The prepared branched gold nanoparticles show efficient surface-enhanced Raman scattering (SERS) properties. Low temperature (4 ℃) is unfavorable to the formation of multi-branched gold nanostructures, and only thin small irregular plate-like nanoparticles are produced. The addition of SDS in TBAB aqueous solution results in forming SDS micelles at much lower concentration of SDS (0.4 mmol/L) as compared to that in pure water, and short branched gold nanoparticles are obtained in the SDS-TBAB system.

Silver Nanourchins in Plasmonics: Theoretical Investigation on the Optical Properties of the Branches

“…Among these new-generation plasmonic objects, particular attention is reserved for nanoparticles which have the unique surface geometry consisting of numerous bumps and thorns protruding from a central spherical core. To date, several methods for the synthesis − and spectroscopic characterization − of Au urchins-like nanoparticles or nanourchins (NUs) have been developed and reported in the literature. Because of their highly tunable surface plasmon resonance (SPR) and excellent surface-enhanced Raman scattering activity, these nanoparticles are promising in optical imaging-based disease diagnostics and therapy .…”