Development of Non-proximate Probe Electrospray Ionization for Real-Time Analysis of Living Animal

Abstract

Ambient ionization mass spectrometry is one of the most challenging analytical tools in the eld of biomedical research. We previously demonstrated that probe electrospray ionization mass spectrometry (PESI-MS) could potentially be used in the rapid diagnosis of cancer. Although this technique does not require a tedious sample pretreatment process, it was not possible for our previously reported setup to be applied to cases involving the direct sampling of tissues from living animal and large animal subjects, because there would not be enough room to accommodate the larger bodies juxtaposed to the ion inlet. To make PESI-MS more applicable for the real-time analysis of living animals, a long auxiliary ion sampling tube has been connected to the ion inlet of the mass spectrometer to allow for the collection of ions and charged droplets from the PESI source (herea er, referred to as non-proximate PESI). Furthermore, an additional ion sampling tube was connected to a small diaphragm pump to increase the uptake rate of air carrying the ions and charged droplets to the ion inlet. is modi cation allows for the extended ion sampling ori ce to be positioned closer to the specimens, even when they are too large to be placed inside the ionization chamber. In this study, we have demonstrated the use of non-proximate PESI-MS for the real-time analysis for biological molecules and pharmacokinetic parameters from living animals.

New strategy for evaluating pancreatic tissue specimens from endoscopic ultrasound‐guided fine needle aspiration and surgery

“…The PESI‐MS analysis was performed using a triple quadrupole mass spectrometer (DPiMS‐8060; Shimadzu Corp.), which has a PESI ion source that replaces the ESI module of the original LCMS‐8060 spectrometer. The mass spectra were acquired for nonneoplastic and PDAC specimens in the positive ion mode, and all subsequent analyses were performed as previously described previously 5–9 …”

Lipidome-based rapid diagnosis with machine learning for detection of TGF-β signalling activated area in head and neck cancer

“…Especially PESI-MS enables acquisition of mass spectra showing profiles of lipid metabolites from a small amount of biological sample (10 mg) with minimal invasiveness and pre-treatment. 16 , 17 The lipidome is informative in the acquisition of malignant phenotypes of tumour cells. 18 Importantly, we explored the intraoperative diagnosis system using PESI-MS combined with machine learning to discriminate cancerous regions from non-cancerous regions in HNSCC.…”

Towards Practical Endoscopic Mass Spectrometry

“…To handle a large size sample such as living animals, the ionization has to be performed, say, at more than 1 m away from the MS instrument, and the remotely generated ions have to be transported back to the ion inlet using extended ion transported tube. 16,17) Instead of sampling the ion, it is also possible to sample the neutral remotely, and transport the sample to an ion source in an online fashion. For sampling analytes from the extracellular uid, microdialysis probe can be coupled to the mass spectrometer for online analysis.…”