Analytical techniques for single-cell metabolomics: state of the art and trends

Single-cell metabolomics is an emerging field that addresses fundamental biological questions and allows one to observe metabolic phenomena in heterogeneous populations of single cells. In this review, we assess the suitability of different detection techniques and present considerations on sample preparation for single-cell metabolomics. Although targeted analysis of single cells can readily be conducted using fluorescent probes and optical instruments (microscopes, fluorescence detectors), a comprehensive metabolomic approach requires a powerful label-free method, such as mass spectrometry (MS). Mass-spectrometric techniques applied to study small molecules in single cells include electrospray MS, matrix-assisted laser desorption/ionization MS, and secondary ion MS. Sample preparation is an important aspect to be taken into account during further development of methods for single-cell metabolomic

Negative mode nanostructure-initiator mass spectrometry for detection of phosphorylated metabolites

The chemical complexity of the metabolome requires the development of new detection methods to enlarge the range of compounds detectable in a biological sample. Recently, a novel matrix-free laser desorption/ionization method called nanostructure-initiator mass spectrometry (NIMS) [Northen et al., Nature 449(7165):1033-1036, 2007] was reported. Here we investigate NIMS in negative ion mode for the detection of endogenous metabolites, namely small phosphorylated molecules. 3-Aminopropyldimethylethoxysilane was found to be suitable as initiator for the analytes studied and a limit of detection in the tens of femtomoles was reached. The detection of different endogenous cell metabolites in a yeast cell extract is demonstrate

Interfacing Microfluidics and Laser Desorption/Ionization Mass Spectrometry by Continuous Deposition for Application in Single Cell Analysis

We present a simple method for continuous deposition of effluent originating from a microfluidic device on a flat metal surface for subsequent analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The sample is delivered using a microscale fused silica capillary and passed onto the surface of a stainless steel plate coated with a layer of a standard matrix. The key parameters optimized in order to obtain high quality and reproducible sample traces are: i) sampleflow rate, ii) speed of the XY-stage movement, and iii) distance of the capillary tip from the plate. Tapering the capillary end as well as surface functionalization to induce hydrophobicity were shown to further enhance the deposition process. The described continuous deposition method is compared with a previously published mass spectrometric method utilizing a piezoelectric microdispenser for microspotting onto the MALDI plates which enabled detection of primary metabolites at the singlecell level. Research is underway to adapt the continuous deposition as an interface for single cell metabolite detection and enhancement of quantitative abilities of the MALDI methodology. We envisage that the presented continuous deposition method may also be suitable for sensitive detection of analytes using other surface analysis tools

Analytical techniques for single-cell metabolomics: State of the art and trends

ISSN:1618-2650ISSN:1618-264

Negative mode nanostructure-initiator mass spectrometry for detection of phosphorylated metabolites

ISSN:1573-3882ISSN:1573-389

Carbon-13 labelling strategy for studying the ATP metabolism in individual yeast cells by micro-arrays for mass spectrometry

Isotopic labelling of cellular metabolites, used in conjunction with high-density micro-arrays for mass spectrometry enables observation of ATP metabolism in single yeast cells.