AVS 51st International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI+AS+SE-ThM

Paper BI+AS+SE-ThM9
PCA of TOF-SIMS Spectra from p(AAm-co-EG/AAc) IPNS on Quartz

Thursday, November 18, 2004, 11:00 am, Room 210D

Session: Surface Modification of Biomaterials
Presenter: D.J. Graham, University of Washington
Authors: D.J. Graham, University of Washington
G.M. Harbers, University of California, Berkeley
K.E. Healy, University of California, Berkeley
D.G. Castner, University of Washington
Correspondent: Click to Email
PCA of TOF-SIMS has been carried out on many well defined model surfaces in structured experiments. These studies have shown the utility of PCA in extracting information from TOF-SIMS experiments from a wide variety of substrate surfaces. This work reports on the application of PCA to a more complex interpenetrating polymer network system. The goal of this project was to verify each step in the IPN synthesis procedure on a quartz substrate. This system presents a challenge to PCA due to the similarity of the polymers used in the IPN and the addition of a peptide chain. PCA of the entire data set (including all synthesis steps for the IPN) showed that PC1 was able to separate most samples. The PC1 loadings were dominated by the overall differences between the hydrocarbons on the bare quartz and the PEG related peak fragments after the addition of the IPN onto the quartz surface. This is likely due to the high PEG content of the IPN polymers. PCA comparing each successive synthesis step gave further insight into the success of the IPN chemistry. PCA was able to distinguish each surface modification up until the addition of the peptide precursor and peptide. The presence of the peptide was verified in subsequent experiments where it was shown that RGD-peptide modified p(AAm-co-EG/AAc) surfaces supported rat calvarial osteoblast adhesion, proliferation, and matrix mineralization. Consequently,surfaces without the RGD peptide or with a control RGE peptide did not support cell attachment. PCA also gave insight into the uniformity of the surface modifications by way of the scores plots. Increasing scatter was seen in the last few synthesis steps suggesting that a less uniform surface chemistry was achieved. The trends seen in the PCA of the TOF-SIMS data were consistent with those seen by XPS.