| AVS 63rd International Symposium & Exhibition | |
| Applied Surface Science | Monday Sessions |
| Session AS+BI-MoA |
| Session: | Practical Surface Analysis I: Advancing Biological Surface Analysis/Imaging Beyond ‘Show and Tell’ |
| Presenter: | Gregory Fisher, Physical Electronics |
| Authors: | G.L. Fisher, Physical Electronics N. Ogrinc Potocnik, Maastricht University, The Netherlands A.L. Bruinen, Maastricht University, The Netherlands J.S. Hammond, Physical Electronics S.R. Bryan, Physical Electronics R.M.A. Heeren, Maastricht University S. Iida, ULVAC-PHI T. Miyayama, ULVAC-PHI |
| Correspondent: | Click to Email |
A recently introduced TOF-TOF imaging mass spectrometer allows conventional TOF-SIMS (MS1) analysis and product ion (MS2) analysis to be achieved simultaneously and in parallel. Secondary ions for MS1 and MS2 analysis are produced from the same area of the surface by a pulsed and digitally raster-scanned primary ion nanoprobe. The sensitivity of the parallel imaging MS/MS spectrometer is high so that the analytical ion dose may be minimized; therefore, precious and one-of-a-kind samples may be probed without significant damage or degradation. Fragmentation of the molecular precursor ions, defined by a 1 Da precursor selection window, is accomplished by collision-induced dissociation (CID) at 1.5 keV in an activation cell of Ar gas at high pressure. Lateral resolutions produced in both MS1 and MS2 images are demonstrated to be in the range of 100 nm < Δl80/20 < 1 μm. This tandem MS imaging capability has been brought to bear for straightforward identification as well as multifaceted studies involving biological, material, and polymer specimens. We will summarize here some of our ongoing biological research, revealing molecular identification at sub-micron practical lateral resolution.
One study concerns song bird ontogeny in male zebra finch (T. guttata). Several sulfatides, phospholipids, sterols and fatty acids have been identified as playing a role in song learning. We have employed parallel imaging MS/MS to unravel the roles of specific molecules because the shortcomings of TOF-SIMS imaging alone does not permit conclusive molecular identification and imaging. We have evidence suggesting that distinct sulfatides are active primarily within the song nuclei while cholesterol and specific fatty acids are active in signaling between the song nuclei.
In other work, we have probed the role of lipids and metabolites in disease states of zebrafish (D. rerio) that have been infected with M. marinum, a form of tuberculosis. The bacteria initiate a granulomatous inflammation, and first signs of the disease are observed in the spleen. We have observed so far that α-tocopherol is elevated in infected tissue as well as in the granuloma, but is not present in the necrotic cells. Cholesterol is elevated primarily in the granuloma. The role of phospholipids appears to differ, specific molecules being either elevated or depressed in the infected tissue. We have preliminary evidence of a metabolic source for bacterial growth. For example, we observe a phosphocholine, PC(16:0/16:0), to be elevated in the granuloma. However, in the necrotic cells surrounding the granuloma we observe elevated signals of a fatty acid, FA(16:0).