Polydisperse Composition of Mixed Monolayer-Protected, Spin-Labeled Au Nanoparticles

• Published in: Analytical chemistry (Washington) Vol. 76; no. 7; pp. 2010 - 2016
• Main Authors: Wellsted, Helen, Sitsen, Esther, Caragheorgheopol, Agneta, Chechik, Victor
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-04-2004
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Gas chromatographic methods; Gold; Nanoparticles; Spectrometric and optical methods; Spectrum analysis; Spin labelling; Gas chromatography; Monolayer; Gold; Fractionation; Transmission electron microscopy; Ligand; Nanoparticle; EPR spectrometry; Polydispersed particle; Exchange reaction
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac035465x

Using EPR spectroscopy and spin-labeled ligands, we have studied product distribution in the ligand exchange reactions of Au nanoparticles. When the incoming ligand was used in excess, the exchanged nanoparticles had uniform composition of the organic shell. Preparative GPC was employed to fractionate these materials according to the diameter of the Au core, as confirmed by TEM, UV, and EPR measurements. When the exchange reaction was carried out with less than a stoichiometric amount of the incoming ligand, nanoparticles with polydisperse composition of the organic shell were formed. This was established by the EPR analysis of the exchange reaction mixtures following their GPC fractionation. The GPC separation of these mixtures is controlled by both Au core size and shell composition.