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Updated: Apr 24, 2026

Synthesis and Characterization of Amphiphilic Gold Nanoparticles
Published on: July 2, 2019
Colloidal stability of zwitterionic polymer-grafted gold nanoparticles in water
Céline Durand-Gasselin1, Régis Koerin1, Jutta Rieger2
1Sciences et Ingénierie de la Matière Molle, PSL Research University, ESPCI ParisTech, Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7615, 10 rue Vauquelin, 75231 Paris Cedex 05, France.
Abstract:
We investigate the colloidal stability of gold nanoparticles (AuNPs) coated with zwitterionic sulfobetaine polymers in aqueous solution. Zwitterionic polymers with different molar masses, synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of N,N'-dimethyl(methacrylamido propyl)ammonium propanesulfonate (SPP) exhibit a well known Upper Critical Solution Temperature (UCST) in water, i.e., phase separate at low temperature. The colloidal stability of gold nanoparticles grafted with PSPP was studied as a function of the temperature. The effects of the molar mass of the grafted polymers, the salt concentration, and the presence of free polymer chains in solution were investigated. UV-vis spectroscopy and dynamic light scattering measurements show that whatever the molar mass of the grafted polymer, the nanoparticles never aggregate at low temperature in pure water. However, a reversible thermal-driven aggregation process of the gold nanoparticles is observed in presence of free polymer chains in solution and explained by a depletion process.
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