Two-Step Functionalization of Neutral and Positively Charged Thiols onto Citrate-Stabilized Au Nanoparticles
Citations Over TimeTop 10% of 2004 papers
Abstract
We propose a two-step approach to functionalize gold nanoparticles prepared by reducing tetrachloroauric acid by trisodium citrate in water. The chloride and citrate physisorbed on the gold nanoparticles are first displaced by thioctic acid (TA), which is then exchanged by thiols containing the desired functionality during the second step. TA bears a carboxylate group and disulfide; at high pH, the negative charge of the former stabilizes gold nanoparticles and the disulfide develops two S−Au bonds, retarding the desorption kinetics upon further functionalization. The slow kinetics of TA desorption is crucial to establishing sufficient steric stabilization for the gold core while losing electrostatic stabilization. Successful attachment of carboxylate, crown ether, cyclodextrin, pyridine, and amino functionalities is verified by surface sensitive techniques. In most cases, ca. 80% of the TA molecules are displaced. The nanoparticles are stable under solution pH where the surface group is ionized. Although at certain solution acidities, the gold sols have difficulty carrying charges and appear flocculated, the nanoparticles become dispersive after being centrifuged and redissolved in suitable buffer solutions, which indicates the successful protection of the gold cores by steric stabilization.
Related Papers
- → Quantification of the Steric Properties of 1,8-Naphthyridine-Based Ligands in Dinuclear Complexes(2022)13 cited
- → An estimate of the steric bulk of the trimethyltin group.(1972)17 cited
- → Primary steric effects in five-membered heterocyclic systems(1971)10 cited
- → Steric Effects. II. General Equations. Application to Cis- and Trans−2-Butene(1948)18 cited
- → Quantification of the Steric Properties of 1,8-Naphthyridine Based Ligands in Dinuclear Complexes(2022)