title: Competitive adsorption of thiolated poly(ethylene glycol) and alkane-thiols on gold nanoparticles and its effect on cluster formation.
abstract: The surface concentration and conformation of thiol-terminated poly(ethylene glycol) (PEG) on gold nanoparticles are studied before and after coadsorption of alkane-thiols. Thermogravimetric analysis (TGA) indicates alkane-thiol ligands will competitively adsorb on gold surfaces of nanoparticles and that the extent of PEG-thiol replacement depends on the specific length of the alkane-thiol molecule. The conformation of the polymer is also affected by the length and packing density of the alkane-thiol. Dynamic light scattering (DLS) shows that the hydrodynamic size of coated particles has an intermediate maximum for the adsorption of octane-thiol, which also forms the most densely packed alkane-thiol monolayers. These two factors greatly impact the formation of clusters by nanoparticle surfactants. Small angle X-ray scattering (SAXS) shows that the largest clusters are formed when particles have a low PEG-thiol surface concentration and an extended PEG conformation.
authors.affiliation: Chemical Engineering Department, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Kjersta
authors.initials: K
authors.lastname: Larson-Smith
authors.forename: Danilo C
authors.initials: DC
authors.lastname: Pozzo
mesh_terms: D000327:Adsorption; D000473:Alkanes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D000473:Alkanes; D013438:Sulfhydryl Compounds; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D006046:Gold