Toward Smaller Aqueous-Phase Plasmonic Gold Nanoparticles: High-Stability Thiolate-Protected ~ 4.5 Nm Cores

M. Mozammel Hoque The University of Texas at San Antonio


Most applications of aqueous plasmonic gold nanoparticles benefit from control of the core size and shape, control of the nature of the ligand shell, and a simple and widely applicable preparation method. Surface functionalization of such nanoparticles is readily achievable but is restricted to water-soluble ligands. Here we have obtained highly monodisperse and stable smaller aqueous gold nanoparticles (core diameter ~ 4.5-nm), prepared from citrate-tannate precursors via ligand exchange with each of three distinct thiolates: 11-mercaptoundecanoic acid, a-R-lipoic acid, and para-mercaptobenzoic acid. These are characterized by UV-Vis spectroscopy for plasmonic properties; FTIR spectroscopy for ligand exchange confirmation; X-ray diffractometry for structural analysis; and high-resolution transmission electron microscopy for structure and size determination. Chemical reduction induces a blueshift, maximally +0.02-eV, in the localized surface-plasmon resonances band; this is interpreted as an electronic (-) charging of the MPC gold core, corresponding to a -0.5-V change in electrochemical potential.


Thumbnail image of Aqueous 4.5 nm gold R1-20190619.pdf
download asset Aqueous 4.5 nm gold R1-20190619.pdf 4 MB [opens in a new tab]

Supplementary material

Thumbnail image of SI-Section of ~ 4.5 nm Au NPs.pdf
download asset SI-Section of ~ 4.5 nm Au NPs.pdf 2 MB [opens in a new tab]
SI-Section of ~ 4.5 nm Au NPs