Agarose gel electrophoresis is used to separate DNA fragments in complex mixtures according to their size. However, because DNA is clear and colorless, these bands cannot be seen with the naked eye. Edvotek® offers several different methods for visualizing the DNA separated by electrophoresis (click here for more information of our DNA stains). One of our most popular stains is the dye-based FlashBlue™ DNA stain. The molecules of FlashBlue™ possess a positive charge, which allows them to bind to the negatively charged backbone of DNA. The DNA fragments are easily visualized because the bound dye molecules stain them with an intense blue color.
FlashBlue™ is included with many of our DNA electrophoresis and PCR kits. However, after performing the experiment, you may find that you have extra stain! Of course, it can be stored in your laboratory for future use, but we’d like to present you with a fun science “magic trick” that can be performed with the leftover stain.
What to do:
1. In a 1 liter flask, dissolve 8 g potassium hydroxide and 10 g glucose in 300 ml distilled water.
2. Add a few drops (0.5 ml or less) of FlashBlue™ stain. Cover the flask and gently swirl to mix.
3. Place the flask on a white surface and allow the liquid to settle – watch the blue color disappear!!!
4. Stopper the flask and vigorously (carefully) swirl or shake the flask – watch the blue color re-appear!!! The more you mix, the darker the color.
5. Set the flask on the lab bench and remove the stopper, and guess what happens? The color disappears again!
(For your convenience, we’ve also created a printable “Quick Guide” for this experiment. You’ll find on our website in our newly-updated Resources section!)
How it works:
An alkaline solution of glucose acts as a reducing agent, changing the FlashBlue™ dye solution from blue to colorless. Shaking the solution raises the concentration of oxygen in the mixture and this oxidizes the FlashBlue™, returning it to its blue form. As the dissolved oxygen is being consumed, the FlashBlue™ is slowly reduced back to its colorless form by the remaining glucose.
We think this is a fun, quick and easy way to dazzle your students AND to teach redox reactions!