AVS 49th International Symposium
    Biomaterials Monday Sessions
       Session BI+VT-MoA

Paper BI+VT-MoA8
PEG-ylated Surfaces with Graded Protein Interactiveness : A ToF-SIMS, XPS and Optical Waveguide Sensor Study

Monday, November 4, 2002, 4:20 pm, Room C-201

Session: Protein Surface Interactions
Presenter: S. Pasche, Swiss Federal Institute of Technology
Authors: S. Pasche, Swiss Federal Institute of Technology
S.M. De Paul, Swiss Federal Institute of Technology
J. Vörös, Swiss Federal Institute of Technology
P. Hug, Swiss Federal Laboratory for Material Testing and Research
B. Keller, Swiss Federal Laboratory for Material Testing and Research
H.J. Griesser, University of South Australia
N.D. Spencer, Swiss Federal Institute of Technology
M. Textor, Swiss Federal Institute of Technology
Correspondent: Click to Email
Poly(L-lysine) grafted with poly(ethylene glycol) (PLL-g-PEG), a polycationic co-polymer positively charged at neutral pH, has been shown to spontaneously adsorb onto negatively charged surfaces, rendering them protein-resistant to a degree related to the PEG surface density. Since the PEG surface density is a function of polymer architecture (PEG molecular weight and grafting ratio expressed as number of lysine monomers per PEG side chain), it becomes feasible to control the interactiveness of a surface by varying the co-polymer architecture. Angle-dependent XPS and ToF-SIMS were used to investigate the surface-chemical properties. The adsorbed mass after serum exposure was determined by an optical sensor technique. Further colloid-modified AFM force measurements aim at studying the mechanical properties of the coated surfaces. PLL-g-PEG was adsorbed onto niobium oxide coated wafers, resulting in the formation of stable polymeric monolayers. The grafting ratio, g, of the polymer was varied systematically between 2 and 10, leading, upon surface adsorption, to highly different, but controlled PEG surface densities. PEG molecular weight was varied between 1000 and 5000. Polymer adsorbed mass was determined quantitatively by an in situ optical waveguide technique. A quantitative relationship was established between EG-monomer surface density, calculated from the known polymer architecture and the surface-adsorbed mass, ToF-SIMS intensities of PEG-, PLL- and substrate-related secondary ion peaks, and the amount of serum proteins that adsorbed onto the different polymer-coated surfaces. PLL-g-PEG surface-coating technology allows the fabrication of surfaces with tailored interactiveness and the establishment of design criteria for PEG-based, protein-resistant surfaces.