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From 2011.igem.org

Make agarose stick to produce agent gradient in the water or medium. Today, we want to know how we can make a solid stick with gradient. In order to show the gradient more visually, we use DNA loading buffer.

Prepare:

gel stick mold: transfer pipet and tube parafilm: to block up the tube agarose TAE buffer beakers dishes DNA loading buffer

1. we mix 0.4g agarose with 40ml TAE buffer which means the final concentration of agarose gel will be 1%.

2. add 4ml heated agarose solution into the tube and after the gel is solidified, we add DNA loading buffer at the end.

DNA loading buffer stays just at the end and there is no gradient occurring after 20min.

3. add 4ml heated agarose solution into the tube and before the gel is solidified, we add DNA loading buffer at the end.

DNA loading buffer sink very quickly. No gradient

4. we have a new idea. We make gel stick little by little. For example, we mix 500µl aqueous gel with 10µl loading buffer and add into the tube. We incubate the tube in cold water to accelerate gel solidification. As a result, the 500µl gel get solidified very quickly(less than 1 min) while the other gel solution remains aqueous. Then we mix another 500µl gel with 20µl loading buffer and add them into the tube. In this way, we make a gel stick with the gradient of DNA loading buffer from 10µl to 60µl.

In a word, we use calculus to solve this problem.