The Invitrogen E-gel Agarose Electophoresis System makes traditional agarose gels almost a thing of the past by using pre-cast gels. No more preparation of buffer, weighing out and melting agarose, dealing with toxic ethidium bromide, pouring the gel and waiting for it to set, etc. Although a variety of E-Gels are available, this review refers only to the 12-well single comb and 18-well double comb formats, as we have no experience with the robotics compatible 96- or 48-well gels.
The E-Gel starter pack includes the E-Gel powerbase and 6 gels, which interestingly, costs less than buying the power base alone! The gel is sealed in a pouch and is easily placed into the powerbase following removal from the pouch. The right hand side is placed into the powerbase first and pushed down to ensure good contact with the electrodes. A 2 min pre-run of the gel is performed after which point the comb can be removed and samples loaded. The wells of each gel can hold up to 20ul (water should be added to any unused wells) and the spacing of the double comb gel allows the use of a multi-channel pipettor for quicker loading. Once the samples are loaded, the single comb gel is run for 30 min (20-25 min for DNA sizes less than 1kb) and the double comb gel is run for 15 min. Ethidium bromide is contained within the sealed agarose gel, thus, visualization may be performed uisng any UV transilluminator and imaging system.
This system from Invitrogen is a real time saver and removes the monotonous task of preparing agarose gels. Although the gels are relatively expensive, the apparatus is economically priced compared to most gel powerpacks. The drawback here is that the powerbase is dedicated and cannot be used to run other equipment. However, the powerbase has a small footprint, which means you can run the gel on your own bench rather than a dedicated spot in the lab. In addition, following use the powerbase can be put in a place that is out of the way.
Although there are many advantages of using the E-Gel systems, the system is relatively expensive compared to the low cost of making agarose gels. In addition, the available E-Gel formats are not exhaustive and the 12- or 18-well gels may be limiting for some applications. Excising bands from the pre-cast gels is not as simple as standard agarose gels due to the sealed unit. Invitrogen does sell an E-gel opener, but we have found it preferable to run these types of gels in the traditional way.
Boyd Scott
Senior Research Scientist
Discovery Biology
Vitae Pharmaceuticals