Smiling effect is caused by difference between the heat dissipation properties of the sides of the gel closer to the spacers and the gel in the middle of the glass i.e. lanes you generally use.

To reduce this effect you can lower the voltage which will decrease current and therefore heat production, reducing smiling effect. Alternatively, you can increase the heat dissipation speed by cooling your gel.

If you have a cold room in your institution, you can run your gel in it (but do not cast the gel in there because cold affects acrylamide polymerization). If you don't have one you can always use a fridge to cool your gel in it. If you don't have an empty fridge, you can try to put your gel tank in a bucket filled with water + ice (be careful not to contact any electrical connection with the water). The latter one seems a bit dangerous but I used it with success and without problem and its very effective because ice cold water outside the tank dissipates heat better than air.

Hope these suggestions can help. Good luck!

The effect can only be nullified by reducing the voltage. Current fluctuation plays a major role so better use a stabilizer. And run the gel at 4oC.

Besides voltage, the quality of the gel is also important, since particles or bubbles present in the gel can also produce that effect.

There are some electrophoresis systems that have an aluminum plate for efficient heat distribution, which helps to avoid this effect when it is caused by nonuniform heating due to high voltage.

2 things that may help:1\ reduce the voltage; 2\ if you have empty lanes (no sample loaded), try loading those lanes with loading buffer as well.

Smiling is artefact caused by heat more particularly by its uneven distribution. You can either reduce the voltage or cool down the gel. Some aparatuses have a connection to water-cooling, so if you have problems with smiling dont hesitate and use it.

Run the gels under cold conditions if possible and at low voltage or current for a longer time. Use only the required amount of amm. persulfate and TEMED for gel preparation

Smiling effect is caused by difference between the heat dissipation properties of the sides of the gel closer to the spacers and the gel in the middle of the glass i.e. lanes you generally use.

To reduce this effect you can lower the voltage which will decrease current and therefore heat production, reducing smiling effect. Alternatively, you can increase the heat dissipation speed by cooling your gel.

If you have a cold room in your institution, you can run your gel in it (but do not cast the gel in there because cold affects acrylamide polymerization). If you don't have one you can always use a fridge to cool your gel in it. If you don't have an empty fridge, you can try to put your gel tank in a bucket filled with water + ice (be careful not to contact any electrical connection with the water). The latter one seems a bit dangerous but I used it with success and without problem and its very effective because ice cold water outside the tank dissipates heat better than air.

Hope these suggestions can help. Good luck!

Smiling effect is caused by temperature differences in gel during electrophoresis, caused by different heat dissipation in the middle and outer parts of the gel. Without thermal stabilization of the gels, the heat from the outer part of the gel is better dissipated and thus cooled, than the middle part of the gel. The result is higher temperature in the middle part. That affects the buffer viscosity in the different parts of the gel, which is strongly dependent on temperature. The higher the temperature, the lower the viscosity (viscosity sinks about 2% with temperature increases of 1 degree Centigrade.). From the physics it follows that molecules move faster in the medium of lower viscosity, meaning that molecules in the middle of gel move faster than in the outer parts of the gel (where they move slower due to lower temperature and higher buffer viscosity), resulting in the so called SMILING GEL BAND PATTERN.

The effect, and its correction is explained in 1980 paper by W. Ansorge, "Thermally Stabilized Very Thin

Gels for DNA and Protein Separation ", as well as ïn the 1981 paper by W.Ansorge and H. Garoff in Analytical Chemistry, ("Improvements in DNA Sequencing Gels Technique").

Thus the smiling effect can be corrected by proper THERMAL STABILIZATION of the gel (e.g. good cooling system over the whole gel). The use of thinner gels is of advantage. With thick gels, it is a compromise between the heat produced (the thicker the gel, the more heat produced at the same voltage applied to gel), and the quality of the gel cooling system. This means that with thicker gels, where the heat transfer to the cooling system is not efficient, often the only help for decreasing the band distortion is to lower the voltage.