A Versatile AuNP Synthetic Platform for Decoupled Control of Size and Surface Composition

Abstract

While a plethora of protocols exist for the synthesis of sub-10-nm gold nanoparticles (AuNPs), independent control over the size and surface composition remains restricted. This poses a particular challenge for systematic studies of AuNP structure-function relationships and the optimization of crucial design parameters. To this end, we report on a modular two-step approach based on the synthesis of AuNPs in oleylamine (OAm) followed by subsequent functionalization with thiol ligands and mixtures thereof. The synthesis of OAm-capped AuNPs enables fine-tuning of the core size in the range of 2-7 nm by varying the reaction temperature. The subsequent thiol-for-OAm ligand exchange allows a reliable generation of thiol-capped AuNPs with target surface functionality. The compatibility of this approach with a vast library of thiol ligands provides detailed control of the mixed ligand composition and solubility in a wide range of solvents ranging from water to hexane. This decoupled control over the AuNP core and ligand shell provides a powerful toolbox for the methodical screening of optimal design parameters and facile preparation of AuNPs with target properties.

Supramolecular Control of Azobenzene Switching on Nanoparticles

“…Inorganic nanoparticles (NPs) functionalized with binary (mixed) monolayers of ligands − provide an attractive platform for inducing intermolecular interactions between the adsorbed species and hence for investigating how various functional groups affect the properties of switchable molecules. An additional advantage of the mixed-monolayer approach is that by decorating NPs with mixtures of functional and solubilizing ligands, it becomes possible, by tuning the composition of the monolayer, to effectively solubilize compounds that are otherwise insoluble in a given solvent .…”

Comparative characterisation of non-monodisperse gold nanoparticle populations by X-ray scattering and electron microscopy

“…Homo-ligand AuNPs stabilised by 11-mercapto-1-undecanesulfonate (MUS) were prepared via thiol ligand exchange from four batches of differently-sized AuNPs that were initially protected by oleylamine (OAm). 42 The core diameter of the four batches ranged from 2-7 nm and varying degrees of size dispersity (ESI, Table S1 †). Two binary mixtures were prepared by mixing MUS-NP1 and MUS-NP4 at weight ratios of 1 : 1 and 1 : 5, labelled as MUS-B1 and MUS-B2, respectively (Table S2 †).…”

“…The MUS ligand and MUS-AuNP syntheses via thiol-for-OAm ligand exchange were carried out following previously published procedures. 42,47 Four batches of MUS-AuNPs weresynthesised with varying reaction temperatures at 40, 25, 15, 10°C and labelled as MUS-NP1-NP4, respectively. We refer to the ESI † for experimental details.…”

Cryogenic electron tomography to determine thermodynamic quantities for nanoparticle dispersions

“…The ligand exchange procedure was adopted from ref. 39. All the particles synthesized and studied in this paper are described in Table 1, where their acronyms are introduced.…”