Bio-Rad GelAir Drying System - Manual (Page 11)

3.2 Drying Other Types of Gels
Drying Gels for Autoradiography/Fluorography (one side exposed)
The following protocol describes a method of layering a sheet of plastic food wrap
between the gel and the top sheet of cellophane. This layering method allows easy separa-
tion of the cellophane sheet from the surface of the dried gel. Uncovering the surface of the
dried gel enables direct exposure of the gel to photographic or X-ray film for autoradiography
or fluorography.
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Cellophane backing
1. Prepare the gel by following the protocol described in Section 3.1, Drying Acrylamide
Gels, steps 1-4.
2. After completing step 4, add a layer of plastic food wrap on top of the gels. Cut the piece
of plastic food wrap to approximately the same dimensions as the cellophane (12.5" x 12.5").
Wet the plastic wrap in water. The wrap does not absorb water, but wetting it helps make
handling easier. Holding one end of the plastic wrap with both hands, drape the other end
across one edge of the plastic frame and lower the sheet to cover the entire frame. If air
bubbles are trapped beneath the plastic wrap, raise the sheet to expose the bubbles and then
lower it again. If this does not eliminate the bubbles, add more water beneath the sheet and
try again. It is important to remove all bubbles to avoid gel cracking.
Fig. 10. Autoradiography gel assembly.
3. Wet the second sheet of cellophane in water and lay it over the plastic wrap, ensuring all
four sides of the cellophane overhang the plastic frame. Bubbles trapped between the
plastic wrap and the top sheet of cellophane can remain. The plastic wrap may appear
wrinkled, but this is normal and should not be a concern. Continue with steps 7-9 of
Section 3.1.
4. With plastic wrap, drying occurs from the bottom, therefore drying times will increase
slightly (no more than 15 minutes).
5. After the gel is dry, carefully peel off the plastic wrap to expose the gel. With only a sin-
gle sheet of cellophane, the gel may curl up. Tape the gel to a more rigid surface to hold
it flat. The gel is now ready for autoradiography or fluorography.
Filter paper backing
Adding a sheet of filter paper to this layering process allows easier handling of thin gels
and insures less gel distortion during drying. 2 Additionally, the dried gel does not curl because
it is attached to filter paper. The following protocol describes how to incorporate filter paper
into the drying sandwich.
1. Prepare the gel by following the protocol described in Section 3.1, Drying Acrylamide
Gels, steps 1-3.
Cellophane
Cellophane
Plastic Wrap
Acrylamide Gel
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