Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure

Journal Article · 03 September 2010 · Journal of Visualized Experiments

DOI: https://doi.org/10.3791/2144 · OSTI ID:1629814

Shrestha, Bindesh ^[1]; Vertes, Akos ^[2]

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1. George Washington Univ., Washington, DC (United States). Dept. of Chemistry; DOE/OSTI
2. George Washington Univ., Washington, DC (United States). Dept. of Chemistry

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell types exhibit heterogeneous biochemical makeup depending on their physiological conditions and interactions with the environment. Conventional methods of mass spectrometry (MS) used for the analysis of biomolecules in single cells rely on extensive sample preparation. Removing the cells from their natural environment and extensive sample processing could lead to changes in the cellular composition. Ambient ionization methods enable the analysis of samples in their native environment and without extensive sample preparation. The techniques based on the mid infrared (mid-IR) laser ablation of biological materials at 2.94 μm wavelength utilize the sudden excitation of water that results in phase explosion. Ambient ionization techniques based on mid-IR laser radiation, such as laser ablation electrospray ionization (LAESI) and atmospheric pressure infrared matrix-assisted laser desorption ionization (AP IR-MALDI), have successfully demonstrated the ability to directly analyze water-rich tissues and biofluids at atmospheric pressure. In LAESI the mid-IR laser ablation plume that mostly consists of neutral particulate matter from the sample coalesces with highly charged electrospray droplets to produce ions. Recently, mid-IR ablation of single cells was performed by delivering the mid-IR radiation through an etched fiber. The plume generated from this ablation was postionized by an electrospray enabling the analysis of diverse metabolites in single cells by LAESI-MS. This article describes the detailed protocol for single cell analysis using LAESI-MS. The presented video demonstrates the analysis of a single epidermal cell from the skin of an Allium cepa bulb. The schematic of the system is shown in Figure 1. A representative example of single cell ablation and a LAESI mass spectrum from the cell are provided in Figure 2.

• Research Organization: George Washington Univ., Washington, DC (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER). Earth and Environmental Systems Science Division; W. M. Keck Foundation
• Grant/Contract Number: FG02-01ER15129
• OSTI ID: 1629814
• Journal Information: Journal of Visualized Experiments, Journal Name: Journal of Visualized Experiments Journal Issue: 43; ISSN 1940-087X
• Publisher: MyJoVE Corp.Copyright Statement
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Issue 43
LAESI
cellular biology
direct analysis
laser ablation electrospray ionization
mass spectrometry
metabolomics
single cell analysis