| AVS 58th Annual International Symposium and Exhibition | |
| Applied Surface Science Division | Tuesday Sessions |
| Session AS-TuM |
| Session: | Imaging and 3D Chemical Analysis |
| Presenter: | Daniel Graham, University of Washington |
| Authors: | D.J. Graham, University of Washington M. Robinson, University of Washington D.G. Castner, University of Washington |
| Correspondent: | Click to Email |
ToF-SIMS imaging is a powerful technique for obtaining chemically specific maps of the surface of a wide range of samples including polymers, metals, tissues, and cells. When combined with the sputtering capabilities of modern ToF-SIMS instruments, one can obtain chemically and biologically specific 3D depth profiles, as well as track chemical signatures throughout a sample volume. This is done with a dual beam approach by taking an image of the surface, sputtering away a given amount of the material and then taking a new image of the freshly exposed area. This process is repeated until the object of interest is gone or the desired depth is reached.
When working with surfaces with significant topography such as the surface of a cell, the z axis of the resulting data cube is not correct. This is due to the fact that each image slice of the surface is displayed as a 2-D image taken from a 3-D surface. This results in a type of inverted topography of the 3D structure within the ToF-SIMS image volume. To correct for this, the National ESCA and Surface Analysis Center for Biomedical Problems NESAC/BIO (Seattle, WA) has developed a Matlab (Mathworks, Natick MA) toolbox to correct the z-axis of cell depth profiles and display the data properly.
Since the shape and topography of a cell can be complex, we have created a set of features of known chemistry and controlled geometry in order to test and validate that the zcorrectorgui is accurately correcting the z-axis. For this, microsphere templating was combined with capillary force lithography to create features of known size and shape. The features sizes were chosen to correspond with the sizes of typical eukaryotic cells. Topographical images of these features were obtained by AFM. After AFM analysis the features were depth profiled by ToF-SIMS. The resulting depth profile data was then imported into the zcorrectorgui and processed. In this presentation we will highlight the results from this study and show example data obtained from a real cell depth profile processed with the zcorrectorgui.