Capillary Electrophoresis with Electrospray Ionization Mass Spectrometric Detection for Single-Cell Metabolomics

Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA.
Analytical Chemistry (Impact Factor: 5.64). 06/2009; 81(14):5858-64. DOI: 10.1021/ac900936g
Source: PubMed


A method that enables metabolomic profiling of single cells and subcellular structures is described using capillary electrophoresis coupled to electrospray ionization time-of-flight mass spectrometry. A nebulizer-free coaxial sheath-flow interface completes the circuit and provides a stable electrospray, yielding a signal with a relative standard deviation of under 5% for the total ion electropherogram. Detection limits are in the low nanomolar range (i.e., <50 nM (<300 amol)) for a number of cell-to-cell signaling molecules, including acetylcholine (ACh), histamine, dopamine, and serotonin. The instrument also yields high-efficiency separations, e.g., approximately 600,000 for eluting ACh bands. The utility of this setup for single-cell metabolomic profiling is demonstrated with identified neurons from Aplysia californica--the R2 neuron and metacerebral cell (MCC). Single-cell electropherograms are reproducible, with a large number of metabolites detected; more than 100 compounds yield signals of over 10(4) counts from the injection of only 0.1% of the total content from a single MCC. Expected neurotransmitters are detected within the cells (ACh in R2 and serotonin in MCC), as are compounds that have molecular masses consistent with all of the naturally occurring amino acids (except cysteine). Tandem MS using a quadrupole time-of-flight tandem mass spectrometer distinguishes ACh from isobaric compounds in the R2 neuron and demonstrates the ability of this method to characterize and identify metabolites present within single cells.

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    • "Electrospray ionization (ESI) is a convenient detection method for CE separations because charged molecules eluting from the CE capillary can be ionized and introduced into the mass analyzer via ESI conditions. CE-MS (see Fig. 3A) is widely used to measure and identify bioactive peptides (Ye et al., 2011), metabolites (Nemes et al., 2011; Nautiyal et al., 2012; Nemes et al., 2012; Gholipour et al., 2013), classical neurotransmitters (Lapainis et al., 2009), and amino acids (Moini, 2013). Alternatively, microdialysis sampling can be directly coupled to ESI MS via nanodroplet segmented flow for in vivo chemical monitoring of neurotransmittes, metabolites, and drugs in the live brain (Song et al., 2012). "
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    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 06/2013; 39(1). DOI:10.1038/npp.2013.145 · 7.05 Impact Factor
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    • "Capillary electrophoresis time-of-flight mass spectrometry (CE- TOFMS) Metabolic changes in response to thalidomide were examined during the neural differentiation of hNPCs using a CE-TOFMSbased metabolomics technique. This approach has been described as a sensitive, selective and rapid analytical method for anionic species, suitable for single-cell metabolomics (Lapainis et al., 2009; Ohashi et al., 2008; Soga et al., 2002 "
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    • "(Reprinted from Oikawa et al., 2011, copyright American Society of Plant Biologists.) LIF, CE can also be combined with MS for the metabolomic profiling of single cells (Lapainis et al., 2009). Detection limits are in the low nanomolar range [i.e. "
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