AVS 47th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeP

Paper BI-WeP13
Characterization of Multi-Component Adsorbed Protein Films by ToF-SIMS

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: M.S. Wagner, University of Washington
Authors: M.S. Wagner, University of Washington
D.G. Castner, University of Washington
Correspondent: Click to Email
Characterization of the adsorbed protein films on biomaterial surfaces is needed for the rational design of biomaterial surfaces. Many surface analysis techniques, however, do not provide efficient means for analysis of these surfaces. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is an excellent technique for the analysis of complex protein films due to its chemical specificity and surface sensitivity. The ToF-SIMS fragmentation pattern is highly complex due to the heterogeneity of the protein composition and the absence of unique, identifying peaks from protein to protein. Analysis of such complex spectra requires the use of multivariate analysis methods to effectively use the ToF-SIMS data. Therefore, we have utilized ToF-SIMS in conjunction with Partial Least Squares (PLS) regression to estimate the surface compositions of binary and ternary adsorbed protein films. Using only the pure component ToF-SIMS spectra, PLS was able to estimate the relative concentrations of the proteins on the surface. Furthermore, using a set of standard protein spectra, Principal Components Analysis (PCA) was able to provide insight into how the composition of a protein film adsorbed from 1% bovine plasma varied with adsorption time. PCA of the ToF-SIMS spectra revealed a shift from mostly fibrinogen to mostly immunoglobulins over the course of two hours. ToF-SIMS/PCA has the tremendous advantage that several proteins can be analyzed in a single experiment, given the appropriate standard spectra. The combination of multivariate analysis methods and ToF-SIMS greatly simplifies the analysis of adsorbed protein films.