In the present paper, we showed the advantages of trapped ion mobility spectrometry coupled too mass spectrometry (TIMS-MS) combined with theoretical calculations for fast identification (millisecond timescale) of polycyclic aromatic hydrocarbons (PAH) compounds from complex mixtures. Accurate PAH collision cross sections (CCS, in nitrogen as a bath gas) are reported for the most commonly encountered PAH compounds and the ability to separate PAH geometric isomers is shown for three isobaric pairs with mobility resolution exceeding 150 (3–5 times higher than conventional IMS devices). Theoretical candidate structures (optimized at the DFT/B3LYP level) are proposed for the most commonly encountered PAH compounds showing good agreement with the experimental CCS values (<5%). The potential of TIMS-MS for the separation and identification of PAH compounds from complex mixtures without the need of lengthy pre-separation steps is illustrated for the case of a complex soil mixture.
The mobilization of nutrient reserves into the ovaries of Aedes aegypti mosquitoes after sugar-feeding plays a vital role in the female's reproductive maturation.
In the present work, we show the advantages of label-free, tridimensional mass spectrometry imaging using dual beam analysis (25 keV Bi3+) and depth profiling (20 keV with a distribution centered at Ar1500+) coupled to time of flight secondary ion mass spectrometry (3D-MSI-TOF-SIMS) for the study of A-172 human glioblastoma cell line treated with B-cell lymphoma 2 (Bcl-2) inhibitor ABT-737. The high spatial (~250 nm) and high mass resolution (m/Δm ~ 10,000) of TOF-SIMS permitted the localization and identification of the intact, unlabeled drug molecular ion (m/z 811.26 C42H44ClN6O5S2−[M-H]−) as well as characteristic fragment ions. We propose a novel approach based on the inspection of the drug secondary ion yield which showed a good correlation with the drug concentration during cell treatment at therapeutic dosages (0 – 200 μM with 4 h incubation). Chemical maps using endogenous molecular markers showed that the ABT-737 is mainly localized in subsurface regions and absent in the nucleus. A semi-quantitative workflow is proposed to account for the biological cell diversity based on the spatial distribution of endogenous molecular markers (e.g., nuclei and cytoplasm) and secondary ion confirmation based on the ratio of drug-specific fragments to molecular ion as a function of the therapeutic dosage.
Skin repair is a significant aspect of human health.
While the
makeup of healthy stratum corneum and epidermis is generally understood,
the mobilization of molecular components during skin repair remains
largely unknown. In the present work, we utilize multimodal, in situ,
mass spectrometry, and immunofluorescence imaging for the characterization
of newly formed epidermis, following an initial acute wound for the
first 96 h of epithelization. In particular, TOF-SIMS and confirmatory
MALDI FT-ICR MS (/MS) analysis permitted the mapping of several lipid
classes, including phospholipids, neutral lipids, cholesterol, ceramides,
and free fatty acids. Endogenous lipid species were localized in discrete
epidermal skin layers, including the stratum corneum (SC), stratum
granulosum (SG), stratum basale (SB), and dermis. Experiments revealed
that healthy re-epithelializing skin is characterized by diminished
cholesterol sulfate signal along the stratum corneum toward the migrating
epithelial tongue. The spatial distribution and relative abundances
of cholesterol sulfate are reported and correlated with the healing
time. The multimodal imaging approach enabled in situ high-confidence
chemical mapping based on accurate mass and fragmentation pattern
of molecular components. The use of postanalysis immunofluorescence
imaging from the same tissue confirmed the localization of endogenous
lipid species and Filaggrin and Cav-1 proteins at high spatial resolution
(approximately a few microns).
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