title: Time dependence of lysozyme adsorption on end-grafted polymer layers of variable grafting density and length.
abstract: A combined experimental and theoretical approach establishes the long-lived nature of protein adsorption on surfaces coated with chemically grafted macromolecules. Specifically, we monitor the time dependence of adsorption of lysozyme on surfaces comprising polymer assemblies made of poly(2-hydroxyethyl methacrylate) brushes grafted onto flat silica surfaces such that they produce patterns featuring orthogonal and gradual variation of the chain length (N) and grafting density (σ). We show that in the kinetically controlled regime, the amount of adsorbed protein scales universally with the product σN, while at equilibrium the amount of adsorbed protein is governed solely by σ. Surprisingly, for moderate concentrations of protein in solution, adsorption takes more than 72 h to reach an equilibrium, or steady state. Our experimental findings are corroborated with predictions using molecular theory that provides further insight into the protein adsorption phenomenon. The theory predicts that the universal behavior observed experimentally should be applicable to polymers in poor and theta solvents and to a limited extent also to good solvent conditions. Our combined experimental and theoretical findings reveal that protein adsorption is a long-lived phenomenon, much longer than generally assumed. Our studies confirm the previously predicted important differences in behavior for the kinetic versus thermodynamic control of protein adsorption.
authors.affiliation: Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27607, USA. Jan_Genzer@ncsu.edu
authors.forename: Jan
authors.initials: J
authors.lastname: Genzer
authors.forename: Shafi
authors.initials: S
authors.lastname: Arifuzzaman
authors.forename: Rajendra R
authors.initials: RR
authors.lastname: Bhat
authors.forename: Kirill
authors.initials: K
authors.lastname: Efimenko
authors.forename: Chun-lai
authors.initials: CL
authors.lastname: Ren
authors.forename: Igal
authors.initials: I
authors.lastname: Szleifer
mesh_terms: D000327:Adsorption; D057219:Biofouling; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry*; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D011102:Polyhydroxyethyl Methacrylate; D012822:Silicon Dioxide; D009113:Muramidase