This project originated from an attempt to build a gel electrophoresis chamber for our lab due to financial constraints of our project. Multiple instructions exist for the build-up of an electrophoresis chamber but were not satisfactory for different reasons. First of all, we wanted to reduce costs and the manual and technical effort to a minimum. Our plan was to avoid the usually performed assembly of acrylic glass (Plexiglas, PMMA) parts to avoid the need for a laser-cutter or huge manual efforts. Instead, we tried to use a 3D-printer that is significantly less expensive, superior for building complex parts and that should reduce the manual effort for the assembly to a minimum – not more than connecting the power supply to the box and the platinum wire. In a second version of our chamber we tried to add the possibility to visualize nucleic acids by using color filters in combination with a blueish light-bulb or LEDs. The system is based on an idea of Clare Chemical Research (http://www.clarechemical.com).

The colored two Plexiglas-squares for our chamber can be easily cut with a saw and are very simple to assemble. In summary, we designed an extremely low cost (<25$ + conductor wire), easy to build gel-electrophoresis chamber with the option to visualize DNA by using visible light. It has nice features like a wiper against condensed water and does not require more than an average-quality 3D printer and common tools like a soldering gun.

1. Chamber Cover

2. Chamber Bottom

3. Wiper

4. Combs (two different pocket sizes)

3D Printing:

We used polylactide PLA as printing material and a 3Dator printer (www.3Dator.de) for the production of our printed parts. All stl-files and a data file for the easy to use CAD program SketchUp is available for download on our Wiki in case you would like to rescale or modify the chamber. We recommend Cura as G-code generator because the support that is inserted for overhang printing was easily removable. The only difficult part was to remove the support material in the guiding rail of the cover that will take a couple of minutes. We used a raft for better adherence as the parts are quite large and an incomplete printing is definitely undesired. The printing time for the biggest part was about 7 hours and the overall amount of material required for all parts was about 300 g PLA.

1. Blue Plexiglas (3mm * 107,5 mm * 98 mm; e. g. C501, Evonik)

2. Orange Plexiglas (3mm * 138,8 mm* 87 mm; high transparency,)

3. Light source (Blueish lightbulb, e. g Sylvania CF9DS-BLUE 9W DULUX S; high power blue LEDs)

The visualization is based on the excitation of the commonly used DNA-staining substances in the blue wave band. The blue light can be either directly generated by using correspondingly colored LEDs or by using a lightbulb and the blue-light Plexiglas-filter. The second, orange filter removes the excitation light and only allows transmitted light of the fluorophore to be visible. This system works well for visibility with the naked eye and has the advantage that the DNA is not exposed to irradiating UV-light. The method is, however, less sensitive than UV-radiation.

The critical step for a good visualization of the DNA is the orange Plexiglas-filter that needs to be highly transparent in order not to diffuse the light and to show well-defined bands. We used an available Plexiglas disc that worked very well but was from an unknown manufacturer. We were not able to find out the exact specifications so that we tried out different other orange plexiglas-discs and found out that better results were seen with increasing transparency. The best-working disc with known specifications that we found goes by the number 2C04 (Evonic, transparency 39%), which is significantly less well suited compared to our initial PMMA-slice but also allowed some visibility. We were able to get low-priced samples of all the Plexiglas discs with adequate size for our application for less than 2$. You should figure out good imaging conditions that also depend on your DNA staining-dye prior to building the chamber. The absorption spectra of the different dyes are available on the manufacturer’s website.

1. Banana plugs (4x), complete length 2.9 cm, plug diameter 4 mm. We decided to use gold-plated plugs to avoid possible corrosion

2. Laboratory sockets (2x), complete length 2.5 cm, screw diameter 5 mm; 1 cm (black), 0.5 cm (black), 0.2 mm (red)

3. Some kind of conductor. We used platinum wire (diameter 2 mm, 13 cm per electrode) that is usually included in commercially available gel-electrophoresis chambers. Other instructions use e. g. monel or copper wire that is less expensive (http://teach.genetics.utah.edu/content/build_gel_box.pdf).

4. Black / red test lead wire, 1 m each, 1.5 mm^2, insulated

Consumables:

- Silicone glue (preferably transparent)

- All purpose glue ated

Tools you will need that are not included in a default toolkit:

- Soldering gun

- Hot air gun

1. Both wires have to be attached to banana plugs on one side for the connection to the power supply. Simply solder or screw down the cable to the plug and use some kind of insulating sleeve for the coating of the banana plug. We used two different insulating sleeves, one with a diameter of 1 cm, one with a diameter of 0.5 cm.

2. Solder the wires to a laboratory socket. Before doing so, mount the insulating sleeves for the socket on the wire because this will not be possible afterwards. The laboratory sockets are screwed into the cover afterwards and tightened using the screw nuts that are attached.

1. Make sure that the holes of the bottom part have the correct size for the banana plugs. The size can be easily adapted using a drilling machine.

2. Placing the conductor is a little tricky. It is helpful to use a small piece of insulating sleeve (1 cm) with a diameter of 2 mm and to mount it on the wire. After heating, the sleeve is still loose and can be moved on the wire. The next step is to contrive the conductor through the hole for the banana plugs and to mount the platinum wire into the corresponding channel. Afterwards you can stuff the insulating sleeve in the cleft next to the banana plugs.

3. The easiest way of connecting the conductor to the banana plugs is wrapping the wire through the holes of the plug before putting the tight-fitting plug into the printed bottom part of the chamber. Prior to inserting the banana plug you should apply some all-purpose glue into the hole to prohibit loosening of the plug and permeability for water.

4. Apply silicon on the mounting area for the blue Plexiglas disk. The silicon sticks well to the PMMA and PLA and the sealing is no problem. Do not use too much of the silicon because it should not ooze out to the upper side of the Plexiglas. The agarose gel would stick to the silicon and would make the removal of the gel difficult. If the Plexiglas fits well there will be no gap that needs filling. If it does not, do not use silicon but instead all-purpose glue as the agarose gel will not stick to the glue.

We used the bottom part of a Dark Reader (copyright Clare Chemical Research) as light source and did not design a special lighting box for the reason of time. The assembly of the chamber should be possible in less than an hour and does not require any complicated technical skills.

We used the bottom part of a Dark Reader (copyright Clare Chemical Research) as light source and did not design a special lighting box for the reason of time. The assembly of the chamber should be possible in less than an hour and does not require any complicated technical skills.

We performed a short experiment to test the stability of PLA against some commonly used chemicals. About 5 mL of the corresponding solution was put on a printed PLA square and the influence on the material was reviewed (25°C, incubation time of 30 min):

PLA is stable against:

  EtOH, Isopropanol, conc. HCL, NaOH 10 M

PLA is not stable against:

  Acetone

• Bottom.stl
• Top.stl
• Wiper.stl
• Comb big.stl
• Comb small.stl
• Gelelectrophoresis chamber.skp

Our special thanks goes to Alexander Schlauer and his 3D-printing company for their technical and functional assistance with this project (www.3Dator.de).