title: Effectiveness of charged noncovalent polymer coatings against protein adsorption to silica surfaces studied by evanescent-wave cavity ring-down spectroscopy and capillary electrophoresis.
abstract: Protein adsorption to silica surfaces is a notorious problem in analytical separations. Evanescent-wave cavity ring-down spectroscopy (EW-CRDS) and capillary electrophoresis (CE) were employed to investigate the capability of positively charged polymer coatings to minimize the adsorption of basic proteins. Adsorption of cytochrome c (cyt c) to silica coated with a single layer of polybrene (PB), or a triple layer of PB, dextran sulfate (DS), and PB, was studied and compared to bare silica. Direct analysis of silica surfaces by EW-CRDS revealed that both coatings effectively reduce irreversible protein adsorption. Significant adsorption was observed only for protein concentrations above 400 microM, whereas the PB-DS-PB coating was shown to be most effective and stable. CE analyses of cyt c were performed with and without the respective coatings applied to the fused-silica capillary wall. Monitoring of the electroosmotic flow and protein peak areas indicated a strong reduction of irreversible protein adsorption by the positively charged coatings. Determination of the electrophoretic mobility and peak width of cyt c revealed reversible protein adsorption to the PB coating. It is concluded that the combination of results from EW-CRDS and CE provides highly useful information on the adsorptive characteristics of bare and coated silica surfaces toward basic proteins.
authors.affiliation: Department of Biomedical Analysis, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands. r.haselberg@uu.nl
authors.forename: Rob
authors.initials: R
authors.lastname: Haselberg
authors.forename: Lineke
authors.initials: L
authors.lastname: van der Sneppen
authors.forename: Freek
authors.initials: F
authors.lastname: Ariese
authors.forename: Wim
authors.initials: W
authors.lastname: Ubachs
authors.forename: Cees
authors.initials: C
authors.lastname: Gooijer
authors.forename: Gerhardus J
authors.initials: GJ
authors.lastname: de Jong
authors.forename: Govert W
authors.initials: GW
authors.lastname: Somsen
mesh_terms: D000327:Adsorption; D045304:Cytochromes c / Q000737:chemistry*; D016264:Dextran Sulfate / Q000737:chemistry*; D019075:Electrophoresis, Capillary; D006583:Hexadimethrine Bromide / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013053:Spectrophotometry; D013499:Surface Properties
chemical_list: D006583:Hexadimethrine Bromide; D012822:Silicon Dioxide; D045304:Cytochromes c; D016264:Dextran Sulfate