AVS 50th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI+SS-WeA

Invited Paper BI+SS-WeA1
Soft X-ray SpectroMicroscopy of Bio-interfaces

Wednesday, November 5, 2003, 2:00 pm, Room 307

Session: Biomolecular Surface Science and Microfluidics
Presenter: A.P. Hitchcock, McMaster University, Canada
Authors: A.P. Hitchcock, McMaster University, Canada
C. Morin, McMaster University, Canada
T. Araki, McMaster University, Canada
J.L. Brash, McMaster University, Canada
R. Cornelius, McMaster University, Canada
S.G. Urquhart, University of Saskatchewan, Canada
U.D. Lanke, University of Saskatchewan, Canada
N. Samuel, University of Washington
D.G. Castner, University of Washington
Correspondent: Click to Email
We are using scanning transmission x-ray microscopy (STXM) and X-ray photoemission electron microscopy (X-PEEM) to study the adsorption of biological and bio-active species on naturally and artificially patterned polymer and molecular substrates. In one area, the thrust is to investigate fundamental issues of protein - polymer interactions relevant to blood compatibility. In a second area, we are providing feedback for the development of patterned bio-active surfaces. Both synchrotron-based microscopies provide chemical speciation by near edge X-ray absorption spectroscopy (NEXAFS). STXM provides quantitative chemical mapping at a spatial resolution of 50 nm, with the possibility of detecting proteins on polymer thin films with monolayer sensitivity in the presence of an aqueous overlayer of the protein solution.@footnote 1@ X-PEEM has greater surface sensitivity than STXM but requires placing the sample in vacuum. Our X-PEEM studies of fibrinogen adsorption on a model polymer substrate, phase segregated polystyrene-poly(methylmethacrlyate) (PS/PMMA),@footnote 2@ indicate clear preference for adsorption on the PS domains when adsorption is performed from a phosphate buffer solution, but preference for adsorption at the PS-PMMA interface when using non-buffered solutions. The strengths, limitations, and future potential of soft X-ray microscopy for studies of bio-interfaces will be discussed.@footnote 3@ @FootnoteText@ @footnote 1@ A.P. Hitchcock et al., J. Biomaterials Science, Polymer Ed. 13 (2002) 919.@footnote 2@ C. Morin et al, J. Electron Spectroscopy 121 (2001) 203.@footnote 3@ X-ray microscopy carried out at the Advanced Light Source (supported by DoE under contract DE-AC03-76SF00098) and the Synchrotron Radiation Centre (supported by NSF under award DMR-0084402). Research supported financially by NSERC (Canada) and the Canada Research Chair Program. We thank the PEEM-2 staff (A. Scholl, A. Doran) for assistance in these studies.