Versatile Route toward Hydrophobically Polymer-Grafted Gold Nanoparticles from Aqueous Dispersions

Abstract

Stabilization of gold nanoparticles in organic solvents is a key challenge in making them available for a wider range of material applications. Polymers are often used as stabilizing ligands because they also allow for the introduction of new properties and functionalities. Many of the established synthesis protocols for gold nanoparticles are water-based. However, the insolubility of many synthetic polymers in water renders the direct functionalization of aqueous particle dispersions with these ligands difficult. Here, we report on an approach for the functionalization of gold nanoparticles, which were prepared by aqueous synthesis, with hydrophobic polymer ligands and their characterization in nonpolar, organic dispersions. Our method employs an auxiliary ligand to first transfer gold nanoparticles from an aqueous to an organic medium. In the organic phase, the auxiliary ligand is then displaced by thiolated polystyrene ligands to form a dense polymer brush on the particle surface. We characterize the structure of the ligand shell using electron microscopy, scattering techniques, and ultracentrifugation and analyze the influence of the molecular weight of the polystyrene ligands on the structure of the polymer brush. We further investigate the colloidal stability of polystyrene-functionalized gold nanoparticles in various organic solvents. Finally, we extend the use of our protocol from small, spherical gold nanoparticles to larger gold nanorods and nanocubes.

Surface polarization, field homogeneity, and dielectric breakdown in ordered and disordered nanodielectrics based on gold–polystyrene superlattices

“…change, and X-ray scattering intensity at low q-values increased. The increase was too low to be explained by agglomeration 33 , and dynamic light scattering did not indicate an increased agglomerate content (see Supplementary Information). Electron microscopy indicated a broadened core diameter distribution of 2.9 nm cores for Au 2.9 nm 9 vol% @PS 11000 (with a width of at least 13 %) and the formation of a fraction of larger particles with diameters up to 8 nm during ligand exchange (Figure S5 in the Supplementary Information).…”

In Situ Formation of Au-Glycopolymer Nanoparticles for Surface-Enhanced Raman Scattering-Based Biosensing and Single-Cell Immunity

“…The hydrodynamic diameter is 33.4 ± 8.0 nm with a polydispersity index (PDI) of 0.057, showing high dispersity of colloids in water (Figure S2). The larger particle diameter by dynamic light scattering (DLS) , compared with TEM size analysis was expected due to the increase in the additional thickness of the water-swellable organic capping layer ,, around the surface of a solid Au nanoparticle (∼18.1 nm) in water. The coating of glycan-based macromolecule was validated by element- and structure-analysis instruments as described below.…”

Advances in design of polymer brush functionalized inorganic nanomaterials and their applications in biomedical arena

“…Stabilizing gold nanoparticles in solvents is key challenge in their further applications in biomedical arena. Sindram et al (2021) developed a novel approach of functionalizing gold nanoparticles with hydrophobic polymeric brushes. They used an auxiliary ligand to transfer gold nanoparticles to organic solvent from aqueous solution and then displaced the ligand with thiolated polystyrene which yielded a dense polymeric brush on the surface of nanoparticles (Figure 13).…”