Introduction: Gel Electrophoresis System (mini)

Instructables tutorial for making a mini-gel electrophoresis system for DNA analysis. Gel electrophoresis systems are essential tools for any molecular biology research, but are often expensive to buy. The total cost of making this DIY system is around $50-$80, depending on where you source the laser cut acrylic parts.

Almost all of the assembly steps described in this tutorial require solvent welding the custom laser cut acrylic parts together using Weld-On #4, a fast-setting, clear, thin liquid cement. Weld-on is applied to the edge with a syringe applicator and drawn into the contact surfaces by capillary action. It is actually an easy and quick procedure, however, be sure to practice welding two scrap pieces of acrylic together if this a new technique to you.

The total length of time to complete assembly is 2-3 hours. Once complete, you will have the following parts:

- A UV-transmissive gel tray for casting a 7 x 7 cm mini-gel and comb;
- An electrophoresis chamber with lid.

Step 1: Parts and Tools

Acrylic materials and design files

From any supplier of acrylic materials (McMaster-Carr, US Plastics etc):

12” x 12” x 1/4" clear acrylic
12" x 12" x 1/4" blue acrylic (or preferred color)
5" x 5" x 1/8" clear acrylic

From McMaster-Carr:

6" x 6" x 1/16" teflon sheet , Cat # 8545K13

From Loop Acrylics:

1/8" solacryl (UV transmissive) - Optional : If you do not need a UV-transmissive gel tray then simply make these parts from regular clear acrylic.

Using the design files attached below, cut the parts from your material - the type of material to use is given in the title of the file. If you do not have access to a laser cutter, you can send the files to any laser cutting service (we use Pololu). These services will also carry most of the material you need with the exception of solacryl.You can also purchase a kit from our online store (IO Rodeo , Cat #IMG-01) for $93. The kit contains all of the laser cut parts and hardware, platinum wire (instead of stainless steel wire) and pre-assembled combs. You will still need to buy the Weld-On.

Hardware and tools

From McMaster-Carr:

2-56 Hand Tap Taper, Cat # 2522A663
Tap Wrench Sliding T-Handle, 0-1/4" (1.6-6.3mm) Tap Size, Cat # 2546A22
2x 2-56 Nylon Pan Head Slotted Machine Screw, 3/16" Length, Cat # 93135A076
4x 2-56 Nylon Pan Head Slotted Machine Screw, 1/8" Length, Cat # 93135A074
Stainless steel wire, 0.01" diam. Cat # 9882K31
2x 6/32 Hex machine nuts Cat # 91841A007
2x Flat Washer, No. 6 Screw Size, 5/16"Cat #  92141A008

From TAP Plastics:

IPS weld-on cement #3 or 4, Cat # 10792
Hypo-type solvent cement applicator, Cat # 25658

From Digi-Key:

2x Banana plug, Cat #655K-ND
Black banana plug cable, 36", Cat # 4771-36-0-ND
Red banana plug cable, 36", Cat # 4771-36-2-ND
4x Rubber feet , Cat # SJ5012-0-ND

Step 2: Comb Assembly

Follow the instructions in these two videos to complete the first step of assembling the gel comb.

Step 3: Gel Tray Assembly

Step 3A
Place the gel tray base flat on the benchtop. Take one of the gel tray sides and insert tabs into the slots at a right-angle with the tray base. Any paper covered sides should be facing OUT. Apply Weld-On to the joint and leave for 2-3 minutes. Position the second gel tray side in place. Before welding, make sure the 2 sides are in the same orientation i.e. with the notch for the combs lined up.
Materials: 2 x gel tray sides; 1 x solacryl gel tray base

Step 3B
Take the two gel tray wings and place paper-side down onto the benchtop. Take the part from Step 1 above and remove any remaining paper backing from the two sides. Place inverted onto the wings as shown in the image opposite so that the tabs and slots are lined up correctly and apply Weld-On to both joints.
Materials: Part from Step 3A; 2 x gel tray wings

Step 3C
Remove any remaining paper backing and insert combs to make sure everything fits correctly.

Step 4: Electrophoresis Tank Assemby

Step 4A
Take the tank base and remove the paper backing from one side. Lay the piece paper-side down on the tabletop. Place the two tank inner sides at a right angle on top of the base so that the edges are flush. Apply Weld-On along the joints.
Materials: 2 x tank inner sides; 1 x tank base

Step 4B
Place the Part assembled above onto the tank feet. Acrylic weld the joint between the two parts.
Materials: Part from Step 4A; 2 x tank feet;

Step 4C
Add the four electrode mounts (with screws) to the tank feet. Make sure that the mounts are in the correct orientation with the screws holes facing away from the center.
Materials: Part from Step 4B; 4 x electrode mounts

Step 4D
On one side, loop a piece of electrode wire over one of the screws. Stretch the wire and loop it over the second screw making sure that the electrode wire is kept straight. Clip the wire on one side while making sure that other side has excess wire (the excess wire will be looped over the banana plug). Repeat on the opposite side. Make sure that the pair of screws with excess wire are on the same side of the tank.
Materials: Part from Step 4C; electrode wire; wire clippers

Step 4E
Take the tank side with no holes and remove one side of paper backing. Lay the piece with paper side down flat on the benchtop. Lay the part from Step 4D side down so that the two wire ends are on the opposite side. Line up with the parts. Acrylic weld along the joints. Take the outer tank side with holes and repeat the process. Note that the wire end should now be on the same side as the holes as shown in the image opposite.
Materials: Part from Step 4D; 2 x colored tank sides (blue shown)

Step 4F
Fit one of the tank outer walls into the assembled part. The part should fit snugly. Weld along all 3 edges. Repeat for the opposite side.
Materials: Part from Step 4E; 2 x tank outer walls

Step 5: Electrode Assembly

Insert the two banana plugs into the holes on the side of the tank. On the inside of the tank, place a washer over the end of the banana plug. Loop the electrode wire 3-4 times over the plug. Finally place the nut on the end of the banana plug and tighten the nut to secure the wire in place. Clip any excess wire. Repeat the process at the second hole to make another electrode.

Materials: Assembled tank from previous step; 2 x banana plugs; 2 x washers; 2 x nuts; wire clippers

Step 6: Lid Assembly

Finally, gather the acrylic parts for making the lid. Remove the paper-backing from one side of all five pieces and weld along the edges to assemble the tank lid. Place the lid on the tank for the finished product !

Materials: 1 x lid base; 2 x lid side (long); 2 x lid side (short)

Step 7: Sample Gel

The sample gel shown in the uploaded image is a 1.2% agarose/TBE gel with SYBR-safe DNA gel stain (Invitrogen). Lanes contain a 1kb DNA ladder (Promega). Gel was electrophoresed at 100 V and viewed with our open source UV transilluminator. Imaging with a digital camera and Cokin A002 filter.