AVS 52nd International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS+BI-TuM

Invited Paper AS+BI-TuM9
Chemical Imaging of Biological Cells and Tissues using TOF-SIMS

Tuesday, November 1, 2005, 11:00 am, Room 206

Session: Surface Characterization of Organic and Biological Systems
Presenter: P. Sjovall, SP Swedish National Testing and Research Institute, Sweden
Correspondent: Click to Email
Although time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been used for chemical imaging of cells and tissues for almost 10 years, recent advances (notably the new primary cluster ion sources) have the potential to lead to a new breakthrough in this area. To realize this, however, additional research is required, addressing issues like (i) sample integrity, (ii) lateral resolution / detection efficiency, and (iii) sample complexity. We have used TOF-SIMS to record the spatial distribution of lipids in freeze-dried mouse brain sections and in surface-adhering polymorphonuclear leukocytes (PMNLs). The mouse brain sections (14 µm thick, cryosectioned, placed on a glass or Si substrate and freeze-dried inside the TOF-SIMS instrument or in a separate vacuum chamber) were analyzed using Au@sub n@@super +@ and Bi@sub n@@super +@ primary ions. It is demonstrated that TOF-SIMS analysis can provide detailed images showing the distribution of a number of lipids on the tissue surface at lateral resolutions down to < 1 µm.@footnote 1@ It is also shown that migration of lipids may be a problem under certain sample preparation and analysis conditions. The PMNLs were analyzed using a chemical imprinting technique, in which the outermost molecular layers of the cells are transferred to a substrate surface by pressing the substrate against the cell sample. The advantage of this method is that the substrate surface can be selected and/or functionalized in a manner that optimizes the subsequent imaging TOF-SIMS analysis. For the PMNLs, chemical imprints were made on Ag substrates in order to improve the detection yield and specificity of the lipids using Ga@super +@ primary ions (taking advantage of the Ag cationization). The resulting images show a complementary localization of cholesterol (plasma membrane) and phosphocholine (nuclear membrane).@footnote 2@ @FootnoteText@ @footnote 1@ Anal. Chem. 2004, 76, 4271@footnote 2@ Anal. Chem. 2003, 75, 3429.