Paper AS-WeM11
Ambient Mass Spectrometry Imaging of Live Cells and Tissues

Wednesday, October 21, 2015, 11:20 am, Room 212D

Currently, mass spectrometry imaging is based on Secondary Ion Mass Spectrometry (SIMS) and Matrix-Assisted Laser Desorption and Ionization (MALDI). Generally specimens for SIMS and MALDI are prepared by cryo-section and drying, which modifies the intrinsic biology due to sample preparations and subsequently does not allow dynamic response studies of biosystems to various chemical and physical stimuli. Most of recently developed ambient mass spectrometry have the spatial resolution in the range of ~50 μm, lacking in celluar and subcellular imaging of cells and tissues.

To investigate the intrinsic biology and dynamic responses of live cells and tissues in the cellular level, we developed an ambient imaging mass spectrometry system with ~5 μm spatial resolution. The ambient imaging mass spectrometry is based on low temperature plasma-surface reaction and desorption and ionization of surface products using near IR (808 nm) laser. Mass imaging is based on the movement of the sample stage. To enhance the laser desorption and ionization, Au nanorods of 10 nm diameter and 40 nm length were used. To further enhancement of sensitivy and possibly membrane specificity, liposome conjugated Au nanorods were used. An orbitrap mass spectrometer with a differential pumping and a pumping load adjustment is used as a mass analyzer.

Colonies of HCT-8 cells and hypothalamus tissues were mass imaged. Hypothalamus tissues were prepared with vibrotome, which allow sectioning of a hypothalamus tissue without freezing. Approximately 40 mass peaks from ~80 amu upto ~ 350 amu were observed with mass imaging. Single cells were observed clearly form a colony of HCT-8 cells and a hypothalamus tissue. Indentification of imaged mass peaks are in progress with mass reference data and mass-mass analysis.