title: Surface Functionalization of Nanoparticles with Polyethylene Glycol: Effects on Protein Adsorption and Cellular Uptake.
abstract: Here we have investigated the effect of enshrouding polymer-coated nanoparticles (NPs) with polyethylene glycol (PEG) on the adsorption of proteins and uptake by cultured cells. PEG was covalently linked to the polymer surface to the maximal grafting density achievable under our experimental conditions. Changes in the effective hydrodynamic radius of the NPs upon adsorption of human serum albumin (HSA) and fibrinogen (FIB) were measured in situ using fluorescence correlation spectroscopy. For NPs without a PEG shell, a thickness increase of around 3 nm, corresponding to HSA monolayer adsorption, was measured at high HSA concentration. Only 50% of this value was found for NPs with PEGylated surfaces. While the size increase clearly reveals formation of a protein corona also for PEGylated NPs, fluorescence lifetime measurements and quenching experiments suggest that the adsorbed HSA molecules are buried within the PEG shell. For FIB adsorption onto PEGylated NPs, even less change in NP diameter was observed. In vitro uptake of the NPs by 3T3 fibroblasts was reduced to around 10% upon PEGylation with PEG chains of 10 kDa. Thus, even though the PEG coatings did not completely prevent protein adsorption, the PEGylated NPs still displayed a pronounced reduction of cellular uptake with respect to bare NPs, which is to be expected if the adsorbed proteins are not exposed on the NP surface.
authors.affiliation: †Fachbereich Physik, Philipps Universität Marburg, 35037 Marburg, Germany.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Pelaz
authors.affiliation: ‡CIC biomaGUNE, 20009 San Sebastian, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: del Pino
authors.affiliation: §Institute of Applied Physics and Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Pauline
authors.initials: P
authors.lastname: Maffre
authors.affiliation: †Fachbereich Physik, Philipps Universität Marburg, 35037 Marburg, Germany.
authors.forename: Raimo
authors.initials: R
authors.lastname: Hartmann
authors.affiliation: ‡CIC biomaGUNE, 20009 San Sebastian, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Gallego
authors.affiliation: ∥Instituto de Nanociencia de Aragon, University of Zaragoza, 50018 Zaragoza, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Rivera-Fernández
authors.affiliation: ⊥Instituto de Ciencia de Materiales de Aragon, CSIC/University of Zaragoza, 50018 Zaragoza, Spain.
authors.forename: Jesus M
authors.initials: JM
authors.lastname: de la Fuente
authors.affiliation: §Institute of Applied Physics and Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.|#Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: G Ulrich
authors.initials: GU
authors.lastname: Nienhaus
authors.affiliation: †Fachbereich Physik, Philipps Universität Marburg, 35037 Marburg, Germany.|‡CIC biomaGUNE, 20009 San Sebastian, Spain.
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
mesh_terms: D016475:3T3 Cells; D000327:Adsorption; D000418:Albumins / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D005340:Fibrinogen / Q000737:chemistry* / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D053758:Nanoparticles / Q000737:chemistry* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry*
chemical_list: D000418:Albumins; D011092:Polyethylene Glycols; D005340:Fibrinogen
keywords: fibrinogen; fluorescence correlation spectroscopy; human serum albumin; nanoparticle; polyethylene glycol; polymer coating; protein corona