PHYC500/2007F:Interactions

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Living cells in an electron microscope?

Electron microscopy requires that cells be "fixed" (chemically cross-linked). Why? Why can't we look at living cells in an electron microscope? - JLT

• I think the reason why we can't look at living things is the fact that we have to put the samples in a vacuum. The EM uses an electron beam to illuminate and create an image of a cell. Hence, molecules in air would scatter the electrons :( -KS user page

• Great answer, Kathrin! This reminded me of a talk I saw a few years ago (I think a scientist from IBM) where they developed a very thin sample chamber that allowed them to do transmission electron microscopy (TEM) on a sample in solution (I think this was a gold nanowire growing). So, the majority of the TEM was in vacuum, except for a thin slice of liquid-phase sample (vacuum tight). So, I think in situ TEM has been demonstrated in proof of principle. I would guess it's pretty difficult to think of doing something similar w/ living cells, but maybe not impossible? (I suppose also the cells would die quickly while being zapped with electrons.)--Steven J. Koch 00:04, 29 August 2007 (EDT)

Controls for cross-linking experiments?

If you use a chemical that can cross-link biological components together (when prepping samples for electron microscopy), what controls could you do to see whether that cross-linking changes the spatial distribution of the components? - JLT

First, I would tag the biological component of interest with a gold particle. Then I would take an image of the sample with no cross-linker. I would then compare an identically prepared sample with cross-linker added. If there exists regions where the gold particles are in higher concentration, as compared to the sample with no cross-linker, I would say that the cross-linker worked.