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Application of MALDI-MSI in Lipids
Date: 100-12-27
Supervisor: Prof. Hui-Fen Wu
Student: Hani Nasser AbdelhamidM.Sc student at NSYSU, Taiwan (ROC)
Tutor at Assuit university, Egypt.
Outline
Introduction
-MALDI-TOF.
-Lipids.Application I.Application II.Summary.Discussion and Questions.
IntroductionMass spectrometry components
•Douglas A. Skoog, F James Holler, Stanley R. Crouch, Principles of Instrumental Analysis, six edition ,Thomson Higher Education 10 Davis Drivt' Belmont,p564.
Mass analyzer
• Quadrupole analyzer.
• Ion trap (IT) instruments,
• time-of-flight (TOF),
• Orbitrap .
• Ion cyclotron resonance (ICR) mass analyzers.
• ESI triple quadrupole (ESI-QQQ).
• QTOF.
Matrix Assisted Laser Desorption Ionization MALDI
Beate Fuchs et.al. Progress in Lipid Research 2010.49 ,450–475
Alexandra P. Kafkaa et.al. International Journal of Pharmaceutics 2011,417 70– 82
Matrix
The matrix
MALDI TOF matrices should be:
1. embed and isolate analytes (e.g., by co-crystallization).
2. be soluble in analyte-compatible solvents.
3. vacuum-stable.
4. absorb the laser wavelength.
5. initiate co-desorption of analyte upon laser irradiation
6. promote analyte ionization .
Matrix Example
Both choice of matrix and sample preparation have been shown to influence the nature of molecules that can be detected using MALDI TOF and the quality of the resulting data
Lipids
• 50–60% of the constituents of cell membranes.
• 20–25% of the Brain dry weight .
Importance
• provide energy for the body( lysosomes ).
• Disorder of lipid distribution cause a lot of disease.
http://www.nationwidechildrens.org/gaucher-disease
http://www.childclinic.net/metabolic/Fabry_disease.html
http://www.sehha.com/diseases/neuro/Alzheimer.htm
Wolman Disease, and Lysosomal acid lipase LAL deficiency .Cell death
Application I
The workflow scheme
CH3
OH
OH
O
OH
OH
OH
O
Cryostat (Leica)
CH3
OH
OH
O
OH
OH
OH
O
2,5 DHAP problem
• Vaccum unstable.• heterogeneous
crystallization.
(a) 2,5-DHB deposition (c) 2,5-DHB/3-AP deposition(b) 2,6-DHAP deposition
250 µm 250 µm 250 µm
2,5 DHB problem
• Vaccum stable.• heterogeneous
crystallization.
(a) 2,5-DHB/ANI (b) 2,5-DHB/DANI
(c) 2,5-DHB/DEANI (d) 2,5-DHB/Pyr
(e) 2,5-DHB/3-AP
automatic microspotter
2,5-DHB/ANI (2,5-DHB/aniline), 2,5-DHB/DANI (2,5-DHB/N,N-dimethylaniline), 2,5-DHB/DEANI (2,5-DHB/N,N-diethylaniline),
2,5-DHB/Pyr (2,5-DHB/pyridine), 2,5-DHB/3-AP (2,5-DHB/3-acetylpyridine).
(a) 2,5-DHB/ANI (b) 2,5-DHB/DANI
(c) 2,5-DHB/DEANI (d) 2,5-DHB/Pyr
(e) 2,5-DHB/3-AP
MALDI(-) .All LIM are same
MALDI(+)
Lipid Search (http://www.lipidmaps.org/)] to determine the compositions of the fatty acid.
Conclusion
LIMs is stable under vaccum.Give high resolution.Economically , cheap.
Application II
Challenge• Presence of adduct ions [M+Na]+, [M+K]+ from solvent.• Contamination from solvent. • Lateral diffusion(analyte delocalization) due to solvent.
Two solvent free techniques, dry-coating and sublimation
The dry-coating techniquedeposits finely ground matrix onto tissue slices by the direct filtering of solid matrix particles through a 20 μm stainless steel sieve.
The workflow scheme
Human Ratina
Salamander
Brain
Kidney
Human Ocular Tissue” Ratina”
Salamander Ratina
Saturated and monounsaturated fatty acids
polyunsaturated fatty acids
Conclusion
• Sublimation is easy technique.
• Reduce contamination from the solvent.
• Generates a very even and uniformly thin layer.
• Reduction in laser spot-to-spot
Summary
Both Techniques” Liquid ionic and sublimation are:
Easy.Available.Enhance MALDI-MSI resolution.Economically, cheap.
Prospective view
• Combination between Liquid Ionic Matrix with Sublimation technique may be will enhance the MALDI-MSI spectra.
Acknowledge
• Assuit university, Egypt
• National sun yat sen university, ROC.
• Prof. Hui-Fen Wu.
• Prof. jiang.
• Prof. Tseng.