Storage

Gels can be stored either wet or dried. To store wet gels, simply place the wet gel onto a sheet of plastic wrap and fold the wrap over the gel. This permits handling the gel without the risk of breakage. Insert the wrapped gel into a plastic bag and seal at 4 ºC up to 1 yr.

Drying gels by vacuum

For vacuum drying on a paper support, use GD 2000 Vacuum Gel Dryer System (Fig 4.4) or equivalent. Place the destained gel onto a sheet of filter paper of the same size. This is placed on a larger sheet of filter paper covering the metal screen on the dryer platen. Cover the top of the gel with plastic wrap and then lower the silicone dryer cover flap. Apply vacuum to seal the flap, then turn on the heater and timer. During vacuum drying, the gel will feel cold relative to the surrounding platen if it is not completely dry. When the temperature of the gel is the same as that of the platen, the gel is dry and the vacuum and dryer can be turned off.

Gels may crack if the vacuum is released before the gel is completely dry, if the vacuum is poor due to a leak in the system, or if the cold trap is full. Some pumps, such as the diaphragm pump, do not require a cold trap and can be attached directly to the dryer for simpler, more reliable operation. The percentage of acrylamide and gel thickness also influence gel cracking. In general, gels >= 0.75 mm thick dry without cracking regardless of the acrylamide percentage. With gels thicker than 0.75 mm,the following guidelines are recommended: Up to 12.5% acrylamide, dry the gel without any special treatments. For >12.5%, add 1–2% glycerol to the final destain or storage solution prior to drying. For thick (>1.0mm) or for high-percentage (>12.5%) gels, place gels back into destain I containing 2% glycerol for 30–60 min before drying to dehydrate and shrink the gel. This reduces cracking by minimizing the shrinkage that normally occurs as gels dry.

Air drying using Easy Breeze™

To air dry, place the gel between two sheets of porous cellophane and lock into the drying frame. Insert the frame into the air dryer and turn on fan and heater. Moisture evaporates through the cellophane, leaving a flat, easy-to-store gel with a clear background. Gels dry in less than 2 h. (Fig 4.5).

Fig 4.4. GD 2000 Vacuum Gel Dryer System.	Fig 4.5 SE 1200 Easy Breeze Air Gel Dryer.