title: Protein interactions with bottle-brush polymer layers: Effect of side chain and charge density ratio probed by QCM-D and AFM.
abstract: Silica surfaces were coated with a range of cationic bottle-brush polymers with 45 units long poly(ethylene oxide) side chains, and their efficiency in reducing protein adsorption was probed by QCM-D, reflectometry and AFM. Preadsorbed layers formed by bottle-brush polymers with different side chain to charge ratio was exposed to two proteins with different net charge, lysozyme and BSA. The reduction in protein adsorption was found to depend on both the type of protein and on the nature of the polyelectrolyte layer. The most pronounced reduction in protein adsorption was achieved when the fraction of charged backbone segments was in the range 0.25-0.5 equivalent to a fraction of poly(ethylene oxide) side chains of 0.75-0.5. It was concluded that these polymers have enough electrostatic attachment points to ensure a strong binding to the surface, and at the same time a sufficient amount of poly(ethylene oxide) side chains to counteract protein adsorption. In contrast, a layer formed by a highly charged polyelectrolyte without side chains was unable to resists protein adsorption. On such a layer the adsorption of negatively charged BSA was strongly enhanced, and positively charged lysozyme adsorbed to a similar extent as to bare silica. AFM colloidal probe force measurement between silica surfaces with preadsorbed layers of bottle-brush polymers were conducted before and after exposure to BSA and lysozyme to gain insight into how proteins were incorporated in the bottle-brush polymer layers.
authors.affiliation: Department of Chemistry, Surface and Corrosion Science, Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden. jeffol@kth.se
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Olanya
authors.forename: Esben
authors.initials: E
authors.lastname: Thormann
authors.forename: Imre
authors.initials: I
authors.lastname: Varga
authors.forename: Ricardas
authors.initials: R
authors.lastname: Makuska
authors.forename: Per M
authors.initials: PM
authors.lastname: Claesson
mesh_terms: D000327:Adsorption; D000818:Animals; D018625:Microscopy, Atomic Force; D009113:Muramidase / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D012822:Silicon Dioxide; D009113:Muramidase