In Situ Pressure Probe Sampling and UV-MALDI MS for Profiling Metabolites in Living Single Cells

Abstract

In this work we describe the use of a combination of a cell pressure probe and a UV-matrix-assisted laser desorption/ ionization time of ight (UV-MALDI-TOF) mass spectrometer for the in situ picoliter sampling and shotgun metabolite pro-ling of living single cells of plants. In addition to quantiiable sampling, the pressure probe has some unique features which diierentiate it from other single-cell analytical tools. Cell wall and plasma membrane properties and water relations of in situ living single cells can be analyzed before sampling the cell sap. In addition, the fully-controlled sampling of cells located at dif-ferent depths in plant tissues, measurement of the sample volume, and the addition of internal standards are facilitated by the pressure probe. Using a variety of organic compounds and nanoparticles as UV-MALDI matrices, metabolites from neutral carbohydrates to amino acids and other metabolites can be detected through UV-MALDI-TOF mass spectrometry analyses of picoliter-sized, single-cell samples.