Sample drying

[Nathan Jones]

I have been attempting to image insect brain sections and have had trouble preventing surface tension during the drying process from destroying a significant % of the ultrastructure of my samples. I have considered using critical point drying but i am concerned about the application of solvent to sample. I am planning to placing my samples on the MALDI plate in a vacuum chamber directly on top of a block of dry ice. I am hoping this will prevent some of my problems. Any thoughts/suggestions are greatly appreciated.

[Markus Stoeckli]

We are typically not too concerned about the damage to the microstructure during the drying process since we image with a maximal resolution of 100 micron. Freeze-drying is commonly used in histology to preserve the tissue structure, but also here we observe some tissue shrinkage.

markus

[Nathan Jones]

I would like to try to get resolution into the 20-40 um range. The raster on the 4700 goes down to 10um i believe. Do you typicaly fix standard “spots” of whatever analyte you are looking for? Recently I started adding spots next to the sections with a std prep of the neuropeptide of interest.

[Markus Stoeckli]

The accuracy of the sample stage is just one thing to consider, but equally important are laser spot diameter and crystal size (see below). Also, smearing of analytes during wet matrix deposition will decrease spatial resolution. We use standards on the same plate to control the reproducibility of the matrix coating and for calibration.

markus

[img]http://www.maldi-msi.org/images/forum/DHB.jpg[/img]
Spray of DB in 70:30 methanol/water

[img]http://www.maldi-msi.org/images/forum/SA.jpg[/img]
Spray of SA in 50:50 ACN/water

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