Sampling and ionization of analyte under ambient conditions are critical for modern mass spectrometry (MS) studies. The sampling size and ionization approach largely determine to which extent a specific MS method can be applied. Recent developments in bioanalytical MS areas, including single cell analysis, MS imaging (MSI) of biological tissues, and protein post-translational modifications (PTMs), greatly depend on the advancements in sampling and ionization methods. We are developing a multifunction device, the Single-probe, for multiple research aims.To fabricate a Single-probe, a dual-bore quartz tube is pulled to a sharp needle (tip <10 �m), and one fused silica capillary (providing sampling solvent) and one nan-ESI emitter are glued into both bores of quartz needle. A small liquid junction (<10 �m) is formed between 2 bores at the Single-probe tip for sampling small targets, and the sampled species is immediately ionized by nan-ESI emitter for MS analysis. The Single-probe has been coupled with a Thermo LTQ Orbitrap XL Mass Spectrometer for studies in 3 different areas. (1) MS of living single cells.  The tip of the Single-probe is small enough to be inserted into living individual cells to analyze species of interest in real-time. A variety of cancer cell lines and anti-cancer drugs have been involved in studies. (2) MSI studies: This set-up can be used to sample compounds on surfaces; scan was performed by moving tissue position placed on a X,Y,Z stage system. We have reconstructed the spatial distributions of lipids and anti-cancer drugs on sample slices of mice organs and tumors.  (3) Ionization of sulfated proteins: The nano-ESI emitter is replaced by a fused silica capillary. Two capillaries were infused with protein solution and acidic solvent, respectively; analytes are ionized at the Single-probe tip. We have generated abundant cations of proteins with PTMs (e.g., phosphorylation and sulfation).

Single-probe: A novel multifunctional device for mass spectrometry studies of single cells, biological tissues, and proteins with PTMs

248th National Meeting (2014)

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