How to reuse and recycle agarose gels

Barely-used pipette tips. Untouched gels. Biology experiments can be expensive and also create a lot of waste. Today we will share a few tips for how to get some extra use out of agarose gels.

Tip 1: Save unused sections of gels for later use

When you cast an agarose gel, you have to make it whatever size your gel electrophoresis system uses. But what if your gel has many more lanes than you have samples? You can cut your gels with a razor and save the unused lanes for another experiment. To make sure you leave enough gel on either side, cut down the middle of a lane.

Left: Cut gels to save portions for later use. In this example, only the portion on the left will be used now, while the rest will be saved for later. Right: Load and run a partial gel as normal. Make sure there is still enough buffer to fully submerge the gel.

Tip 2: Reuse gels that don’t contain DNA stain

If you have back-to-back classes, gels that were used to run dye samples (like our Molecular Rainbow, Microbe Hunters, or Cat Genetics labs) can be reused multiple times. Just be sure to run one class’s samples completely off the gel before your next class reloads it.

Tip 3: Recast gels for gel loading practice

If a gel has been made with a DNA stain, it can’t be used again for sample analysis. But you can get extra mileage out of stained gels by saving them for your students to practice loading.

Save used gels in an airtight container, and when it is time for your students to practice gel loading, melt the used gels back down and recast “new” gels. Simply put old gels in a flask or similar heatproof vessel and heat slowly in a microwave or over a hot plate, swirling periodically. Once the agarose has completely liquefied (i.e., no chunks of gel are visible and the molten agarose appears clear), cast gels as you would with fresh agarose.

Re-casting gels in this way has the benefit of dissipating any dye fronts that were present on the gel, and also means you don’t have to worry if the wells tear while the gels are in storage.

Left: Used gels ready to be melted down. Right: A “new” gel cast from used gels is absolutely acceptable for gel loading practice!

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