Single Cell Lipidomics: Characterizing and Imaging Lipids on the Surface of Individual Aplysia Californica Neurons with Cluster SIMS

• Published in: Analytical chemistry (Washington) 2013-02, Vol.85 (4)
• Main Authors: Passarelli, Melissa K., Ewing, Andrew G., Winograd, Nicholas
• Format: Article
• Language: English
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac303038j

Neurons isolated from Aplysia californica , an organism with a well-defined neural network, were imaged with secondary ion mass spectrometry, C 60 -SIMS. A major lipid component of the neuronal membrane was identified as 1-hexadecyl-2-octadecenoyl- sn -glycero- 3 -phosphocholine [PC(16 : 0e/18 : 1)] using tandem MS. The assignment was made directly off the sample surface using a C 60 -QSTAR instrument; a prototype instrument that combines an ion source with a commercial ESI-MALDI mass spectrometer. Normal phase liquid chromatography mass spectrometry (NP-LC-MS) was used to confirm the assignment. Cholesterol and vitamin E were also identified with in situ tandem MS analyses and compared to reference spectra obtained from purified compounds. In order to improve sensitivity on the single cell level, the tandem MS spectrum of vitamin E reference material was used to extract and compile all the vitamin E related peaks from the cell image. The mass spectrometry images reveal heterogeneous distributions of intact lipid species, PC(16 : 0e/18 : 1), vitamin E and cholesterol on the surface of a single neuron. The ability to detect these molecules and determine their relative distribution on the single cell level, shows that the C 60 -QSTAR is a potential platform for studying important biochemical processes, such as neuron degeneration.