As you should remember, agarose gel electrophoresis is a technique that uses electricity and a porous gel matrix to separate DNA (and other molecules) into discreet bands based on size, shape, or charge. The agarose gel used to separate the molecules is like thick Jell-O. Last week, we went viral on TikTok when we shared the all-too-relatable thought about eating those agarose gels when we are done. In brief, DON’T eat the gels you’ve used for DNA electrophoresis in your lab! Let’s talk about why you shouldn’t eat in the lab (or, eat your lab experiments!), and what you can do to make edible electrophoresis as a fun lab, outreach, or Halloween activity!
To properly identify the hazards, first let us identify and discuss all the components necessary for electrophoresis.
- Agarose – a seaweed polysaccharide used as the matrix that is use as the matrix to separate molecules. The gel is solid, yet satisfyingly squishy! For the percentages we use in the lab, it feels like a thick Jell-O. In actuality, food grade agarose is completely safe for human consumption, and it is used in many foods as a vegan substitute for gelatin. One of its most interesting food uses is in “Raindrop cakes,” which are a low percentage of agar powder dissolved in water and shaped into domes. It is really important to note that you should get food-grade agar to ensure that there are no harmful contaminants present in the gel.
- Buffer — this solution of buffers and salts keeps biomolecules charged while also allowing electricity to flow through the system. For our experiment, we are using a Tris-Acetate-EDTA buffer. The acetate comes from acetic acid, which we use at home in its diluted form, vinegar. The EDTA is a chelating agent that removes metals from proteins (like enzymes that chew up DNA). It is safe for use as a food preservative. Tris is a buffer that keeps the pH of the sample around pH 7, a normal biological pH. This buffer is not used as a food additive but is found in some medications to stabilize the pH. Furthermore… this probably doesn’t taste very good! Vinegar, salt and bitter buffer likely doesn’t make for a tasty experience.
- Samples — the molecules we are using electrophoresis to separate. In theory, these are all safe for consumption. For example, DNA and RNA is present in the foods we eat (since they consist of living cells). In many of our experiments, students analyze DNA extracted from E. coli. While the DNA alone is not harmful, it does have the potential to contain live bacteria. Many of the dyes used in our kits are the same ones used to color candy. However, they are not certified as food-grade reagents and could potentially contain contamination.
The next thing to consider is where you’re making (and eating) the gel. Although we just told you the reagents themselves were more or less safe to eat, most labs (research, outreach, school, even home labs), contain chemicals that are quite dangerous for human consumption. In our facility, we have toxic, poisonous, and caustic chemicals, bacteria and viruses, and even some chemicals that create dangerous fumes. Even with the best safety precautions in place, contamination can happen, and so we recommend against eating in the lab, or using lab glassware to make something consumable (and the NSTA agrees with us). Thus, making and running your gels in the lab then eating them remains a big no-no.
However, it is important to recognize that there are ways to perform real electrophoresis using food-safe reagents and simplified electrophoresis systems. Remember, we just need buffer, agarose, samples, and a way to run the gels. Below are some food-safe reagents that we can use to make edible gels.
- Agarose — When ordering, you want to look for a food safe agar (sometimes called agar agar). This is a little less purified than lab-grade agarose, but it will still perform simple separations, with the benefit of safe for consumption. Agar can be found online at Amazon and other retailers, or at Asian specialty food stores.
- Buffer — In our research, we have found two food safe buffer systems that can be used for electrophoresis.
- Science Buddies uses baking soda, or sodium bicarbonate, as a buffer system for home electrophoresis. This is cheap and easy to make, but it might not be tasty.
- According to the paper “Inexpensive and safe DNA gel electrophoresis using household materials”, found here, Crystal Light Lemonade can be used as a buffer system because of the citric acid/sodium citrate included in the drink mix. The important note is that the pH should be adjusted to 7 before use. One way to introduce inquiry would be to try several different drink mixes to see how well they work.
- Samples — Really, the best samples to use in this case are mixtures of food dyes. These can be found at any grocery or craft store in the cake decorating section. You will want to make the solutions with at least 5% glucose (final concentration) to ensure that they are more dense than the buffer and can settle into the wells. We have some resources for doing food dye electrophoresis in our Sweet Science presentation.
Next, you are going to want to create an electrophoresis chamber to be dedicated to food-grade materials. It would be expensive to purchase a full electrophoresis system just for our edible experiments, so there are a few resources to make them at home.
- The “Household Materials Electrophoresis” article mentioned above gives a great tutorial on how to create a “soap box” electrophoresis system using inexpensive household materials. These are not going to provide the superior separation that a lab-grade electrophoresis chamber produces, but to explain the concept they’re going to do the trick.
- There are electrophoresis chamber models available for 3d printers (like this one), but with a few caveats. You’re going to want to make sure the plastic that you use is both food safe and can withstand the high temperatures from dishwashing the plastic, the melted agarose and from the electrophoresis itself. We’re not experts in this area, but here is some information we found that discusses food safe plastics. Please be sure to fully research this before proceeding!
Good luck with your experiments and be sure to let us know if you’ve eaten your science!
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