title: Control of the PEO chain conformation on nanoparticles by adsorption of PEO-block-poly(L-lysine) copolymers and its significance on colloidal stability and protein repellency.
abstract: The physical adsorption of PEO(n)-b-PLL(m) copolymers onto silica nanoparticles and the related properties of poly(ethylene oxide) (PEO)-coated particles were studied as a function of the block copolymer composition. Copolymers adopt an anchor-buoy conformation at the particle surface owing to a preferential affinity of poly(L-lysine) (PLL) blocks with the silica surface over PEO blocks when a large excess of copolymer is used. The interdistance between PEO chains at particle surface is highly dependent on the size of PLL segments; a dense brush of PEO is obtained for short PLL blocks (DP = 10), whereas PEO chains adopt a so-called interacting "mushroom" conformation for large PLL blocks (DP = 270). The size of the PEO blocks does not really influence the copolymer surface density, but it has a strong effect on the PEO layer thickness as expected. Salt and protein stability studies led to similar conclusions about the effectiveness of a PEO layer with a dense brush conformation to prevent colloidal aggregation and protein adsorption. Besides, a minimal PEO length is required to get full stabilization properties; as a matter of fact, both PEO(45)-b-PLL(10) and PEO(113)-b-PLL(10) give rise to a PEO brush conformation but only the latter copolymer efficiently stabilizes the particles in the presence of salt or proteins.
authors.affiliation: Univ. Bordeaux/IPB, ENSCBP, 16 avenue Pey Berland, 33607 Pessac, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Louguet
authors.forename: Anitha C
authors.initials: AC
authors.lastname: Kumar
authors.forename: Nicolas
authors.initials: N
authors.lastname: Guidolin
authors.forename: Gilles
authors.initials: G
authors.lastname: Sigaud
authors.forename: Etienne
authors.initials: E
authors.lastname: Duguet
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lecommandoux
authors.forename: Christophe
authors.initials: C
authors.lastname: Schatz
mesh_terms: D000327:Adsorption; D000818:Animals; D002417:Cattle; D003102:Colloids; D006863:Hydrogen-Ion Concentration; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry*; D009994:Osmolar Concentration; D011092:Polyethylene Glycols / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties
chemical_list: D003102:Colloids; D012492:Salts; D011107:Polylysine; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D012822:Silicon Dioxide