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Lipidomics in Human Cancer and Malnutrition
Published in Qiu-Xing Jiang, New Techniques for Studying Biomembranes, 2020
Iqbal Mahmud, Timothy J. Garrett
MSI is an emerging tool in lipidomics research, which allows untargeted analysis and structural characterization of lipids directly from a tissue section. There are several MSI analysis approaches, but the two most common are Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI-MSI) and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI) where DESI-MSI occurs under ambient conditions and MALDI-MSI most often is accomplished under vacuum although atmospheric pressure MALDI is still performed.40–43
Particles
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
Desorption electrospray ionization-mass spectrometry (DESI-MS) was evaluated as an alternative approach to MALDI-TOF-MS, where a matrix compound was required, and succeeded in the detection of the MS2 coat protein from crude samples with minimal sample preparation (Shin et al. 2007).
Emerging Biomedical Analysis
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Many variants of ESI have been developed in recent years. Ambient ionization is a family of techniques that was derived from ESI to enable rapid MS analysis at lower cost. Ambient ionization techniques generate ions under ambient conditions for subsequent MS analysis directly on the sample with minimum sample preparation (Cooks et al. 2006, Nyadong et al. 2007). Representative ambient ionization techniques are desorption electrospray ionization (DESI) and direct analysis in real time (DART). In the DESI technique, an electrospray of charged solvent droplets hits the sample surface and extracts analyte molecules to form secondary droplets (Fig. 2). The secondary droplets undergo a similar ionization process with ESI and eventually are delivered to the inlet of a mass spectrometer (Takats et al. 2004). In the DART methodology, an electrical potential is applied to a helium gas stream to generate metastable species. These excited-state gas molecules subsequently react with the analyte surface to form ions (Cody et al. 2005). Due to the simple and cost-effective experimental setup, DESI, DART and other ambient ionization techniques, such as paper spray ionization, liquid microjunction surface sampling probe (LMJ-SSP) and rapid evaporative ionization mass spectrometry (REIMS), were used in several clinical studies (Li et al. 2017). Examples of clinical applications of ambient ionization MS will be discussed later in this chapter.
DropWise: current role and future perspectives of dried blood spots (DBS), blood microsampling, and their analysis in sports drug testing
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
M. Thevis, Katja Walpurgis, A. Thomas
Using desorption electrospray ionization (DESI) or paper spray (PS) ionization, untreated DBS samples can also be ionized in their native environment and directly analyzed by MS [42]. During DESI, an electrically charged solvent spray is directed at the sample, which results in the release of ions from its surface toward the MS system [50]. For PS ionization, a paper triangle is cut from the DBS card, or used as a pre-designed paper probe, and solvent plus direct current voltage are applied to generate the spray [51]. The target compounds are extracted from the DBS by the solvent and migrate to the tip of the triangle to form charged droplets, which undergo desolvation before entering the mass spectrometer. Meanwhile, this technique can be automated using single-use paper strips, a multi-sample plate (24 strip VeriSpray sample plate), and the respective plate loader and magazine (VeriSpray Plate Loader + Magazine), which can hold up to 10 plates and load them into the VeriSpray Ion Source (Thermo Fisher, San Jose, CA, USA) [52]. Both DESI and PS ionization techniques have been successfully applied to DBS analysis; however, they are less sensitive than other approaches, as only small blood volumes can be extracted and the omission of both sample preparation and LC separation can result in matrix effects and interferences, which will then require strategies of analytical compensation [42,52].
Insights and prospects for ion mobility-mass spectrometry in clinical chemistry
Published in Expert Review of Proteomics, 2022
David C. Koomen, Jody C. May, John A. McLean
Owing to these analytical advantages, the use of IM-MS in clinical settings is increasing rapidly. This review aims to identify current and future directions of IM-MS in clinical analyses by outlining several experimental approaches that may prove advantageous in clinical settings. First, multidimensional analysis of exogenous compounds in complex biological matrices will be described to highlight the analytical advantages of IM-MS for routine testing as well as the bioinformatics required for collision cross section (CCS) library identification. Second, mass spectrometry imaging of tissues for diagnostic purposes is becoming more prevalent in some clinical areas. The integration of IM with matrix-assisted laser desorption ionization (MALDI) or desorption electrospray ionization (DESI) imaging mass spectrometry provides additional filtering and structural information for more confident compound identification for tissue analysis. Finally, deployment of IM and MS in clinical settings is described by two example applications: intraoperative tumor margin delineation with MS and its impact on surgical environments and breath analysis of volatile organic compounds with IM for identification of biomarkers or disease state of patients. Both provide rapid analysis to acquire real-time data to improve diagnoses. Prospects and new advances in IM-MS for improved clinical analyses are also described.
Role of MALDI-MSI in combination with 3D tissue models for early stage efficacy and safety testing of drugs and toxicants
Published in Expert Review of Proteomics, 2020
Chloe E Spencer, Lucy E Flint, Catherine J Duckett, Laura M Cole, Neil Cross, David P Smith, Malcolm R Clench
Conventional methodologies to localize molecules in tissue samples or in vivo include immunofluorescence microscopy [2], positron emission tomography (PET) [3], and magnetic resonance imaging (MRI) [4]. However, these methodologies have limitations such as requirements for the addition of fluorescent labels, or magnetic or isotopic probes. However, addition of such a probe can have an effect on therapeutic pathways or can alter biological compositions, and additionally such probes have limited use with human subjects. Mass spectrometry imaging (MSI) is an established method which can simultaneously map a variety of molecules within a tissue, without the use of labels. MSI applications extend to a range of ionization techniques including, but not limited to, matrix-assisted laser desorption ionization (MALDI), desorption electrospray ionization (DESI), and liquid extraction surface analysis (LESA). MALDI-MSI is the most widely used technique with high spatial resolution and increasing speed of acquisition, which make it an appealing analytical method for high-throughput drug development studies. The multiplex nature of MALDI-MSI also enables the analysis of different tissue types and biological models for quantitative applications detecting a range of molecules including metabolites, lipids, peptides, and proteins [5–8].