| AVS 54th International Symposium | |
| Biomaterial Interfaces | Thursday Sessions |
| Session BI-ThP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | S. Muramoto, University of Washington |
| Authors: | S. Muramoto, University of Washington D.J. Graham, Asemblon, Inc. R. Michel, University of Washington M.S. Wagner, Proctor & Gamble Co. T.G. Lee, Korea Research Institute of Standards and Science D.W. Moon, Korea Research Institute of Standards and Science L.J. Gamble, University of Washington D.G. Castner, University of Washington |
| Correspondent: | Click to Email |
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a powerful surface analysis technique for the characterization of organic surfaces due to its high surface sensitivity, molecular specificity, and high mass resolution. However, the fragmentation patterns of positive secondary ions from adsorbed proteins, produced by primary ion bombardment, are complex due to multiple fragments originating from each of the 20 amino acids present in proteins. Therefore, the multivariate analysis technique principal component analysis (PCA) was used to identify fragment peaks that vary significantly between spectra. This study utilized Cs+, Au+, Au3+, Bi+, Bi3+, Bi3++, C60+, and C60++ ion sources to generate mass spectra for five single-component proteins (albumin, fibrinogen, lysozyme, collagen and immunoglobulin G) adsorbed onto mica. With the use of PCA, we observed differences in fragmentation patterns among the ion sources for all proteins. However, the differences between ion sources for a given protein were smaller than the differences between different proteins. This allows the type of protein to be identified regardless of the ion source used. For each of the five proteins, the fragmentation patterns generated from Cs+, Au+ and Au3+ ions were differentiated at the 95% confidence level. For the Bi ion sources, the fragmentation patterns from the Bi+ ions were differentiated from the fragmentation patterns from the Bi3+ and Bi3++ ions at the 95% confidence level, but the fragmentation patterns from the Bi3+ and Bi3++ ion sources could not be differentiated. From the PCA loadings it appears that there may be a dependency between the mass of the ion source and the number of carbon atoms in the emitted secondary ions (i.e., the Au ions may produce more smaller fragments than the Cs ions). Also, sampling depth may play a role in the observed differences between monoatomic and the cluster ion beams. The results from this study show how the combination of TOF-SIMS with PCA can be used to identify the influence of primary ion type on secondary ion fragmentation patterns.