Exploring Single-probe Single-Cell Mass Spectrometry: Current Trends and Future Directions

The Single-probe is a multifunctional device that can be coupled to mass spectrometry (MS) for molecular analysis of microscale samples, such as single cells, tissue slices, and multicellular spheroids, under ambient conditions. In Single-probe single cell MS (SCMS) studies, this technique leverages direct sampling and nanoelectrospray ionization (nanoESI), enabling the analysis of cells in their native environments without the need for extensive sample preparation. The Single-probe SCMS techniques have been used for a variety of different studies at the single-cell level, including semiquantitative profiling of metabolites, quantification of target molecules, cell-cell interactions, and incorporated chemical reactions for extended molecular analysis. Due to its miniaturized design and versatility, the Single-probe has been utilized for MS imaging (MSI) of tissue sections and investigation of extracellular molecules in live single spheroids. This review summarizes recent advancements in Single-probe-based techniques and their applications, with a focus on SCMS studies, emphasizing their potential utility in advancing MS methodologies in microscale bioanalysis.