Usually to visualise proteins or biological polymers in Transmission Electron Microscopy, negative staining with uranyl acetate or phosphotungstic acid is performed but i simply drop casted my protein-polymer (alginate) complex on TEM grid and my proteins are seen as dark dots even without negative staining, the buffers used were simple sodium acetate and sodium phosphate.
Yes, if you put something on a TEM grid, you will also see something in the TEM. The darkness of the image will correspond to the thickness and density of that something. However, if you want usable, let's call it nice, images of a protein, you will need to put more effort into it.
However, it can be good to also take a look at your sample without negative stain, since then you will be able to detect impurities in your sample solution, impurities in the formvar/carbon films, or detect the formation of crystals that stem from the salts in the suspension buffer. I believe that might explain some of the images you provided.
@martin schauflinger thank you so much for your answer, i will look into it
hello,
Your dark dots in image1 may be your sample but visible without staining because it is very thick so stopping electrons.
Image3 looks like a part of a tree structure for me, corresponding to your dry/precipitated/crystallized buffer.
In image1, between the dark dots, objects seen may be also salt crystals.
Maybe dilute more your sample and vortex it to break big aggregates.
When your sample is attached on the film, wash it with water (Mq, distillate) to remove salts.
Your buffer is not simply sodium acetate and sodium phosphate, it is lot of salts.
Nicolas Barois thank you so much for your answer, in image 3, actually the elongated tree like structure is nothing but the polymer alginate, at neutral pH it exists in extended form while at low pH which in this case pH 3, it shrinks due to deprotonation of its carboxyl groups. image 1 is of pH 3 and rest 2 images are of pH 7. The image 2 is one protein and in image 3 is another protein both of them belong to lysozyme family.
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