Direct tissue analysis of phospholipids in rat brain using MALDI-TOFMS and MALDI-ion mobility-TOFMS

Abstract

After water, lipids are the most common biomolecules found in the brain (12%). A brief perusal of the physiology, anatomy, and pathophysiology of the brain illustrates the importance of lipids. Recent advances in mass spectrometry have allowed the direct probing of tissues. However, most studies have focused on proteins. In the present work, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and MALDI-ion mobility (IM)-TOFMS were employed for direct analysis of phospholipids in rat brain tissue. Molecular ions (MH ϩ ) corresponding to phosphatidylcholines, phosphatidylethanolamines, and sphingomyelin, were recorded. When studying pharmacology, we learn that many therapeutic compounds are stored in the body's adipose tissue. MALDI-TOFMS and MALDI-IM-TOFMS were thus used to analyze rat brain tissue with chlorisondamine added directly onto the tissue slice. With both techniques, noncovalent complexes between the tissue phospholipids and chlorisondamine were detected. In addition, MALDI-IM-TOFMS of noncovalent complexes between phospholipids and chlorisondamine displayed a mobility between that of an isobaric lipid and peptide. (J Am Soc Mass Spectrom 2005, 16, 133-138)

Feasibility of Higher-Order Differential Ion Mobility Separations Using New Asymmetric Waveforms

“…In cylindrical and spherical FAIMS geometries, this causes focusing that keeps ions near the gap median (counteracting diffusion and Coulomb repulsion), 46,49 which greatly improves sensitivity and permits ion trapping at high pressures. 58,59 This effect would become stronger with increasing n because the dependence of E C on E D gets steeper, as follows from eqs (11), (16), (19), and (21). Therefore, HODIMS could also be performed in cylindrical geometries where ion focusing is critical, and enable the operation of atmospheric-pressure ion traps analogous to t-FAIMS.…”

“…Any of these pairs results in: (19) i.e., the separation is independent of K(0), a, and b. By comparison of eqs (11), (16), and (19), the numerical coefficient with the leading term at separation order n equals 4 1 -n : 1/4 for n = 2, 1/16 for n = 3, and 1/64 for n = 4. This trend supports the above postulate of a 1:2:2:2 ratio for waveform segment durations.…”

“…4a-l). Any of them provides separations primarily by coefficient d: (21) with the leading term coefficient equal to 1/4 of 1/64 in eq (19), following the rule postulated above. Again, these waveforms produce ion trajectories with different Δ r (C E ≅ 0.209, C E ≅ 0.282, or C E ≅ 0.320) and so would yield a different instrumental response.…”

“…[4][5][6][7][8][9][10] Recent commercial introduction of such systems [11][12][13][14] is expanding interest in ion mobility/MS, particularly for analyses of complex biological samples such as proteolytic digests and lipids, nucleotides, and metabolites. [15][16][17][18][19][20][21][22][23][24] Single-stage ion mobility spectrometry (IMS) was investigated since the 1970s, [25][26][27] with a noteworthy development of ESI/IMS in 1980s. 28 In IMS, ions drift through a non-reactive buffer gas under the influence of a modest electric field.…”

Direct MALDI-MS analysis of cardiolipin from rat organs sections

“…The detailed sectioning and sections handling methodology was done as previously reported [17]. The sections were collected onto stainless steel MALDI targets and briefly thaw-mounted before storage at Ϫ20°C.…”