title: Size-selective separation of polydisperse gold nanoparticles in supercritical ethane.
abstract: The aim of this study was to use supercritical ethane to selectively disperse alkanethiol-stabilized gold nanoparticles of one size from a polydisperse sample in order to recover a monodisperse fraction of the nanoparticles. A disperse sample of metal nanoparticles with diameters in the range of 1-5 nm was prepared using established techniques then further purified by Soxhlet extraction. The purified sample was subjected to supercritical ethane at a temperature of 318 K in the pressure range 50-276 bar. Particles were characterized by UV-vis absorption spectroscopy, TEM, and MALDI-TOF mass spectroscopy. The results show that with increasing pressure the dispersibility of the nanoparticles increases, this effect is most pronounced for smaller nanoparticles. At the highest pressure investigated a sample of the particles was effectively stripped of all the smaller particles leaving a monodisperse sample. The relationship between dispersibility and supercritical fluid density for two different size samples of alkanethiol-stabilized gold nanoparticles was considered using the Chrastil chemical equilibrium model.
authors.affiliation: Centre for Nanoscale Science, Department of Chemistry, The University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom.
authors.forename: Dylan P
authors.initials: DP
authors.lastname: Williams
authors.forename: John
authors.initials: J
authors.lastname: Satherley
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D004980:Ethane / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D053758:Nanoparticles; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D011312:Pressure; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013499:Surface Properties; D014466:Ultraviolet Rays
chemical_list: D001672:Biocompatible Materials; D006046:Gold; D004980:Ethane