May Someone please explain the mechanism of negtive staining of protein-samples by uranyl acetate (For TEM).

Thanks,
Manu Lopus

Please see: http://www.ru.ac.za/administrative/emu/micr30105.htm

"A drop of the solution containing the biological sample (e.g., Viruses) is deposited on to the grid and after the excess has been taken off, a drop of the "negative staining" solution is then deposited on to the grid.

After a few seconds the excess is drained off and the grid allowed to dry before observation in the TEM The "negative staining" solution, being a heavy metal salt (e.g. phosphotungstic acid, uranyl acetate), and thus electron opaque, deposits around the relatively electron transparent virus particles (see also diagram below). This causes the virus particles to appear light against a dark background on the TEM screen, hence the term "negative staining"."

I hope this helps. The figure on the webpage is also very helpful.