I am working with macro-molecules composed of phospholipids in the 1 to 5 micron range and am having difficulty finding a microscopy tool to examine them under. I know cryo-sem would work, but the local universities near me do not have that capability, would cryo-tem work? Or would the beam not pass through these particles (they are spherical I believe).
Large liposomes (several micron in size) will definitely flatten on the EM grid. You would likely be able to see through them since they will not be spherical anymore. You will definitely see the "edge" of the liposomes.
With the typical voltage of a TEM microscope (300 kV) you can see through approximately 500 nm thick samples. Also depending on the buffer composition inside the liposomes the contrast can be worse, in case there are sugars or glycerol in there.
Cryo-TEM would work well on the smaller sizes. Depending on the kV of the TEM, the particles are getting too large to image them as complete spheres within ice. The larger particles might flatten in ice that is thinner than the original diameter of the spherical particles. It shouldn't matter if this happens as you just want to visualise the composition of the particles; I assume.
Yes, the beam will pass through the particles. That is the magic part of cryo-TEM; you get phase contrast images of your material where the TEM defocus resolves your features of interest.
Cryo-TEM is a great method for liposomes and avoids the damage that other techniques (e.g. freeze-fracture) can cause. There's actually an ASTM work item in this area close to completion so a standard will be with us shortly. See:
https://www.astm.org/DATABASE.CART/WORKITEMS/WK54615.htm
Large liposomes (several micron in size) will definitely flatten on the EM grid. You would likely be able to see through them since they will not be spherical anymore. You will definitely see the "edge" of the liposomes.
With the typical voltage of a TEM microscope (300 kV) you can see through approximately 500 nm thick samples. Also depending on the buffer composition inside the liposomes the contrast can be worse, in case there are sugars or glycerol in there.
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