Most SEM preparation does not use osmium. Try it iwithout osmium tetroxide in the first instance. Osmium tetroxide gives enhanced preservation of lipids which is useful as with SEM one is ofter viewing membranes. As a heavy metal it may reduce charging to some extent.

OK. I want to make a SEM for enveloped virus. Thank you.

For your task you do not need osmium tetroxide.

Hello Edigar,

You will be workimg at quite high magnifictions with a field emission SEM. I assume that the osmium would reduce the extraction of material which otherwise can leave surface mottled with small holes visible at high magnification (my personal belief). I would still try without osmium if you cannot obtain it.