title: Control of protein adsorption: molecular level structural and spatial variables.
abstract: The adsorption of fibrinogen (Fb) and bovine serum albumin onto polycrystalline Au coated with HS(CH2)3O(CH2CH2O)5CH3 was determined by surface plasmon resonance from bare Au (0% coverage) to the complete ( approximately 100% coverage) self-assembled monolayer (SAM). Both proteins exhibit similar adsorption curves with common onset ( approximately 60% coverage) and range ( approximately 60% to 80% coverage) of minimal protein adsorption. Reflection-absorption infrared spectroscopic data show that widespread order is not present in the films over this range of coverage, indicating loosely packed, bound oligomers that are uniformly distributed and fully screen the underlying substrate. On the basis of our data, we propose a mechanism of protein rejection by oligo(ethylene oxide) (OEO)-modified surfaces in terms of changes in free energy (DeltaGsystem; system = protein + surface) due to oligomer conformational constriction over an area greater than the contact area. Minimal protein adsorption corresponds to the maximum DeltaGsystem for a given compression. This controlled study of protein adsorption provides insights into the molecular level understanding of protein adsorption unavailable from previous polymer and comparative SAM studies.
authors.affiliation: Biotechnology Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8313, USA. david.vanderah@nist.gov
authors.forename: David J
authors.initials: DJ
authors.lastname: Vanderah
authors.forename: Hongly
authors.initials: H
authors.lastname: La
authors.forename: Jessica
authors.initials: J
authors.lastname: Naff
authors.forename: Vitalii
authors.initials: V
authors.lastname: Silin
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Rubinson
mesh_terms: D000327:Adsorption; D005340:Fibrinogen / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D007700:Kinetics; D011092:Polyethylene Glycols / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D020349:Surface Plasmon Resonance; D013816:Thermodynamics
chemical_list: D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D006046:Gold; D005340:Fibrinogen