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.