3. Add the sugar-embedding (usually glucose) buffer into the
reservoir and fill it to the top.
4. Cut a section of carbon-coated mica sheet from Subheading
3.1.1 into a size similar or slightly smaller than the EM grid
(about 3 Â 3 mm
2 ). Float the carbon film on the surface of the
glucose solution. The floated carbon film should be flat and not
split. If the carbon film is split, change the mica and float
another piece of the carbon film.
5. Use an anti-capillary self-closing tweezer to pick up a molybdenum grid. Insert the grid deep into the sugar-embedding
buffer and then slowly pick up the floated carbon film from the
bottom of the carbon film (Fig. 6).
Fig. 6 Schematics of back-injection and carbon-sandwich method. The floated carbon film is picked up by a
molybdenum grid from the bottom. The crystal suspension is mixed with the embedding sugar on the opposite
of the grid. For back-injection method, a filter paper is used to blot away all the remaining solution. For
carbon-sandwich method, a second carbon film is introduced to apply on top of the grid. An additional filter
paper is used to blot away all the remaining solution. After the grid specimen is dried, the grid specimen can
be directly cooled down in liquid nitrogen
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