Influence of molecular environment on the analysis of phospholipids by time-of-flight secondary ion mass spectrometry.
Understanding the influence of molecular environment on phospholipids is important in time-of-flight secondary ion mass spectrometry (TOF-SIMS) studies of complex systems such as cellular membranes. Varying the molecular environment of model membrane Langmuir-Blodgett (LB) films is shown to affect the TOF-SIMS signal of the phospholipids in the films. The molecular environment of a LB film of dipalmitoylphosphatidylcholine (DPPC) is changed by varying the film density, varying the sample substrate, and the addition of cholesterol. An increase in film density results in a decrease in the headgroup fragment ion signal at a mass-to-charge ratio of 184 (phosphocholine). Varying the sample substrate increases the secondary ion yield of phosphocholine as does the addition of proton-donating molecules such as cholesterol to the DPPC LB film. Switching from a model system of DPPC and cholesterol to one of dipalmitoylphosphatidylethanolamine (DPPE) and cholesterol demonstrates the ability of cholesterol to also mask the phospholipid headgroup ion signal. TOF-SIMS studies of simplistic phospholipid LB model membrane systems demonstrate the potential use of these systems in TOF-SIMS analysis of cells.
Department of Chemistry, Pennsylvania State University, 152 Davey Lab, University Park, Pennsylvania 16802, USA.
Audra G
AG
Sostarecz
Donald M
DM
Cannon
Carolyn M
CM
McQuaw
Shixin
S
Sun
Andrew G
AG
Ewing
Nicholas
N
Winograd
D002784:Cholesterol / Q000737:chemistry; D008567:Membranes, Artificial; D008954:Models, Biological; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010767:Phosphorylcholine / Q000032:analysis* / Q000737:chemistry*; D018629:Spectrometry, Mass, Secondary Ion
D008567:Membranes, Artificial; D010714:Phosphatidylethanolamines; D010767:Phosphorylcholine; C007510:1,2-dipalmitoyl-3-phosphatidylethanolamine; D002784:Cholesterol