Staining methods uranyl acetate method

Specimens for electron microscopy were prepared as thin cross-sections and stained with uranyl acetate and lead citrate. A JEOL lOOB electron microscope was used to obtain the electron micrographs. Reconstruction of sections of these micrographs by Fourier filtration methods was done in collaboration with Dr. J. Frank of New York State Department of Health, Albany, N.Y. 

The staining technique for TEM uses a material that absorbs electrons and preferentially attaches itself to or reacts with certain regions of the polymer rather than other regions. Materials frequently used are uranyl acetate and osmium tetroxide. For polyethylene the technique of chloro-sulphonation can be used. In this method, which involves immersing the sample in chlorosulphonic acid, the electron-absorbing material becomes attached to lamellar surfaces, so that lamellae (see section 3.4.2) with their planes parallel to the direction of the electron beam become outlined in black in the micrographs. 

TEM or SEM examination of inclusion compound...The blue stained (alginate-iodine compound) film sample and the red stained(alginate-Food color Red No.105 compound) bead sample were stained negatively with 57o uranyl acetate, made by the usual method and observed by 200kV TEM (Hitachi H-800). The shrunk and hard bead separated from acetic acid (alginate-cholesterol adduct) sample was prepared in the same manner described above(for SEM sample) and observed by SEM(Hitachi S-430). 

The lamellar structure is best studied using TEM. Let us take polyethylene. Two methods of preparation are commonly used staining with chlorosulphonic acid/uranyl acetate and etching with permanganic acid. 

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