Electroelution is one of the numerous methods available for DNA extraction from agarose gel. Here, I have described some of the specialized electroelution apparatus. These can easily be used to isolate DNA from the agarose gel. Though these apparatuses may be expensive to buy they offer an easy and convenient way of DNA extraction from agarose gel.
These instruments have been designed in such a way that takes less time to consume and easy to handle than any other traditional methods. Among many such types of apparatuses; V-chamber, G-CAPSULETM, and some electrophoretic apparatuses with built-in transilluminator are of great importance.
1. DNA electroelution using V-chamber
DNA extraction from agarose gel using the V chamber is an electrophoresis-based method in which DNA fragments are resolved in an agarose gel. After that excise the desired DNA band from the agarose gel using a sterile surgical blade. Fill up the electrophoresis tank with the same buffer in such a way that the buffer is equally distributed on each side of the mid-plateau but not into the mid-plateau.
Place the excised band into the sample chamber as close as possible to the V channel. place only one gel slice per well and load enough buffer to cover the gel slice. Flush the V chamber with a pasture pipette to make sure that there is no air bubble trapped with gel slice. After that gently add 100 µl of 10 M ammonium acetate inside the V chamber. The salt cushion; 10 M ammonium acetate buffer contains bromophenol blue to help visualization. After that, gently close the lid in order to prevent the resuspension of the high salt cushion.
After the electrophoresis completes, collect 400 µl of eluted DNA from the V chamber and place it into a 1.5 µl of Eppendorf tube for the ethanol precipitation. The recovery rate is 75 %, however, the process is time-consuming. This is because it involves the ethanol precipitation and resuspension into elution buffer for ready-to-use downstream applications.
2. DNA electroelution using G-CAPSULETM
The extraction of DNA from agarose gel using G-CAPSULETM is a much more convenient way that consumes less time. This is one of the advanced techniques developed to purify desired DNA fragments from the agarose gel in a simple way. It requires less effort and gives a high recovery rate (up to 90 %) in an elution volume of 25-50 µl.
G-CAPSULETM has two parts; the G-PickTM G-TrapTM. G-PickTM is used to pick up the DNA band from the agarose gel. G-PickTM with the piece of the gel is assembled with the G-TrapTM (it traps the migrating DNA) as shown in the picture.
The assembled G-CAPSULETM is then attached to an accessory product G-CAPSULETM weight. After that, submerge the set up in the buffer on a horizontal electrophoresis system. G-CAPSULETM weight prevents the G-CAPSULETM from floating during electrophoresis. During the run, DNA migrates towards the positive terminal and is captured by the G-TrapTM. G-PickTM contains a membrane that traps the DNA.
Use of the G-CAPSULETM removes many additional steps including purification steps unlike the commercially available kits and other traditional methods. In addition to that, it also maximizes the DNA recovery rate without affecting the DNA quality. To buy the G-CAPSULETM, visit the GBIOSCIENCE website.
3. DNA electroelution using electrophoresis with built-in illuminator
Recently, there are some electrophoresis setups have been devised for the electroelution based DNA extraction from agarose gel. These are integrated with the built-in illuminator. The development of these instruments has led us to utilize illuminator while performing the electrophoresis. This helps to view the DNA migration in real-time. These setups are portable, handy, and require lesser reagents as compared to the traditional ones.
These setups are portable, handy, and require lesser reagents as compared to the traditional ones. MupidTM-One LED Illuminator, BlueGelTM Electrophoresis System, and E-Gel® Safe ImagerTM Real-time Transilluminator are some of the most popular setups.
Though they are the expensive ones they provide a convenient way of extracting DNA fragments from the agarose gel. These instruments remove the necessity of further purification. I have grouped this procedure under the in-gel isolation of DNA fragments because it removes the two steps; gel excision and purification. Among these three apparatuses, E-Gel® Safe ImagerTM Real-time Transilluminator is my choice. It is handy, portable, and easy to perform. However, it comes with its own gel; E-Gel® CloneWellTM gel.
The E-gel has been designed in such a way that it contains sample wells as well as collection wells. You just need to load the DNA sample into the sample wells and put the TE buffer in the corresponding collection wells. Put distilled water in the rest of the blank wells and run the electrophoresis. Turn on the LED light and monitor the DNA migration. Once the DNA of interest reaches the collection well, you can collect the DNA sample directly from the collection well which is ready-to-use.