AVS 56th International Symposium & Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP13
ToF-SIMS Study of Fibronectin Orientation on Self-Assembled Monolayers

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Session: Biomaterial Interfaces Poster Session I
Presenter: L. Árnadóttir, University of Washington
Authors: L. Árnadóttir, University of Washington
J. Brison, University of Washington
L.J. Gamble, University of Washington
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Protein adsorption and orientation plays a critical role in many biomedical applications. Fibronectin (FN) is an extra cellular matrix protein that is involved in many cell processes such as adhesion, migration and growth. The orientation and conformation of FN adsorbed onto surfaces can therefore have a critical effect on cell-surface interactions. In this study the adsorbed orientation and conformation of the 7-10 fragment of FN (FNIII7-10) was studied on four different model surfaces (self-assembled monolayers (SAM) of C11 alkanethiols on Au, -CH3, -NH2, -COOH and -OH terminated SAM). The FNIII7-10 fragment incorporates both the Arg-Gly-Asp (RGD) FN receptor binding motif and the PHSRN synergy site which participate in the RGD binding. The effect of different surface chemistries on binding and adsorption configuration was investigated using X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). XPS showed significantly higher protein coverage on the hydrophobic -CH3 terminated surface than the hydrophilic and negatively charged –COOH terminated surface. Both XPS data and SIMS peak intensities for certain amino acid were used to verify the adsorption process and monolayer coverage. Full coverage was determined by a plateau in SIMS peak intensities with increasing protein exposure. A principal component analysis (PCA) of the ToF-SIMS data on surfaces with similar sub-monolayer protein coverage was then used to determine changes in the spectra that differed when the fragment was adsorbed on various surfaces. These results are related to different orientation or conformations of the fragment on the different surfaces.