Invited Paper BI-MoM1
Multimodal Nano-Bio Imaging of Neuronal Cells and Tissues

Monday, December 8, 2014, 8:40 am, Room Milo

Secondary ion mass spectrometry (SIMS) provides molecular specific information but for 2D imaging, SIMS needs specimens in general, to be frozen and dried for analysis in vacuum. For 3D imaging, specimens can be sputter profiled by recently developed gas cluster ions. To compensate the distortion due to cryosection and sputter profiling, we have been trying to develop a multimodal mass and non-linear optical imaging methodology of various cells and tissues for neuronal studies. In this presentation, multimodal SIMS and CARS imaging studies on neuron cells, olfactory bulb, and nematode C. elegans are reported.

For time-of-flight (TOF) secondary ion mass spectrometry (SIMS) imaging, 30 keV Bi₃⁺ ions for 2D mass imaging and 30 keV Ar₁₀₀₀ cluster ions for depth profiling were used to analyze various tissues such as C. elegans, and mouse olfactory bulb. As a complementary non-linear optical imaging, coherent Anti-Stokes Raman Scattering (CARS) were used to get 3D lipid imaging down to ~50 μm with 300 nm spatial resolution in-vitro or ex-vivo.

For C. elegans, lipid CARS imaging was obtained for live C. elegans but for SIMS imaging, C. elegans were dried with water and sputtered with 30 keV Ar₁₀₀₀ cluster ions to get sectioned 2D SIMS images. Molecular specific SIMS imaging for lipids, neurotransmitters, and pheromones with complementary CARS lipid imaging were used to investigate the difference of molecular distributions in wild-type and various mutant C. elegans.

For a cryosectioned mouse olfactory bulb, SIMS imaging showed different distributions of lipid molecules and neurotransmitters which is consistent with the olfactory bulb structure of glomerulus, mitral cell layer, and granule cell layer. SIMS imaging to study the changes of neurotransmitters in an olfactory bulb upon odorant stimulus will be reported.

In conclusions, multimodal mass and non-linear optical imaging provides a practically useful platform to investigate cells and tissues for new biomedical understanding of neuronal systems. New challenges for non-cryo tissue section, plasma/fs laser based ambient mass spectrometry for live cell membrane mass imaging, and super-resolution CARS will be discussed.