title: Charge-based characterization of nanometric cationic bifunctional maghemite/silica core/shell particles by capillary zone electrophoresis.
abstract: In view of employing functionalized nanoparticles (NPs) in the context of an immunodiagnostic, aminated maghemite/silica core/shell particles were synthesized so as to be further coated with an antibody or an antigen via the amino groups at their surface. Different functionalization rates were obtained by coating these maghemite/silica core/shell particles with 3-(aminopropyl)triethoxysilane and 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane at different molar ratios. Adequate analytical performances with CE coupled with UV-visible detection were obtained through semi-permanent capillary coating with didodecyldimethyl-ammonium bromide, thus preventing particle adsorption. First, the influence of experimental conditions such as electric field strength, injected particle amount as well as electrolyte ionic strength and pH, was evaluated. A charge-dependent electrophoretic mobility was evidenced and the separation selectivity was tuned according to electrolyte ionic strength and pH. The best resolutions were obtained at pH 8.0, high ionic strength (ca. 100 mM), and low total particle volume fraction (ca. 0.055%), thus eliminating interference effects between different particle populations in mixtures. A protocol derived from Kaiser's original description was performed for quantitation of the primary amino groups attached onto the NP surface. Thereafter a correlation between particle electrophoretic mobility and the density of amino groups at their surface was established. Eventually, CE proved to be an easy, fast, and reliable method for the determination of NP effective surface charge density.
authors: Laboratoire d'Electrochimie et Chimie Analytique, Paris, France.
authors: Fanny
authors: F
authors: d'Orlyé
authors: Anne
authors: A
authors: Varenne
authors: Thomas
authors: T
authors: Georgelin
authors: Jean-Michel
authors: JM
authors: Siaugue
authors: Bruno
authors: B
authors: Teste
authors: Stéphanie
authors: S
authors: Descroix
authors: Pierre
authors: P
authors: Gareil
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D053758:Nanoparticles / Q000737:chemistry*; D009994:Osmolar Concentration; D010316:Particle Size; D011437:Propylamines / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D014325:Tromethamine / Q000737:chemistry
chemical_list: D000596:Amino Acids; D005290:Ferric Compounds; D011437:Propylamines; D012821:Silanes; D014325:Tromethamine; C088294:3-aminopropyltrimethoxysilane; C000499:ferric oxide; C040733:tetraethoxysilane; D012822:Silicon Dioxide