Chapter 6 - Probe electrospray ionization/mass spectrometry and its applications to the life sciences

Abstract

In this chapter, the principle of probe electrospray ionization (PESI) and its applications in the life sciences are introduced. In the first section, the unique nature of PESI and the development of commercially available instruments supplied by Shimadzu Corporation are briefly explained. PESI was developed by Hiraoka et al. in 2007, where an ultrathin needle probe (the tip diameter is ordinarily under 1μm) was used as a sampling and ionization unit. Owing to such a thin needle probe, PESI achieves low-invasive sampling from a microscopic area, which, in fact, leads to various applications of PESI. In the second section, applications that use PESI, especially the combinational use of PESI with highly selective mass spectrometers such as tandem mass spectrometry or high-resolution mass spectrometry are introduced. In particular, previously reported studies on single-cell analysis, real-time monitoring of a living mouse, imaging mass spectrometry, and forensic applications are reviewed. Following the above contents, other ambient ionization techniques similar to PESI, such as wooden-tip ESI and robotic surface analysis mass spectrometry (RoSA-MS), are introduced, and future perspectives of PESI are discussed.