User:Brian P. Josey/Notebook/2010/04/09

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Preliminary Success

With the piece of wood that Dan carved out for me, I was able to create the magnetic yoke in the lab today. It was actually fairly simple to set up. Like I detailed earlier, I designed it so that the yoke follows a rectangle of magnets running around with a gap in one end. The piece of wood is added to prevent the gap from closing under the force of the magnets themselves. Here is a picture of the yoke as we have it set up in the lab:

I created a flow cell with about 10 uL of my stock of 10:1 ferritin solution, as shown in the center of the picture, and positioned it in the gap so that the coverslip of is resting against the apex of the cone. This provides the smallest gap between the magnet and the ferritin proteins in the solution. The hope was that there would be a build up of ferritin near the tip of the magnet.

After waiting for an hour to let as much of the ferritin aggregate as possible, a crescent shape blotch developed in the flow cell around the tip of the cone. At first I thought it was just gunk, but after we checked it out it was clear that we could move it. Because of this we believe that it is ferritin. After playing with flow cell and positioning it in different orientations around the inside of the yoke, we could move the blotch around. Koch tried using only the cone magnet to see if he could move the ferritin. He couldn’t, confirming the necessity of directing the field lines around with the yoke. Here is a picture of the flow cell:

The blotch is near the upper left corner of the flow cell. If you aren’t familiar with our flow cells, the actual flow cell area is marked off by the tape on the top and bottom, and the nail polish on the left and right. So it is the darker area just to the right of the left nail polish marker. I created a second flow cell to confirm the experiment, but with all the moving around of the flow cells to look at the movement, and time constraints, I wasn’t able to get enough of the ferritin to sufficiently aggregate. I will be repeating this process on Monday.

Steve Koch 22:34, 9 April 2010 (EDT): Congrats! This is a great foothold. Unfortunately, the ferritin is similar color to the wood grain, so it's tough to see in the photo. But I can confirm with my own eyes that there was a dense spot of ferritin created by the field gradient near the tip. This spot was easy to move around the flow cell. If they were monodisperse ferritin proteins before accumulating, then it is a very good sign! Larry had the good idea to encase the ferritin in tiny water droplets in oil as a way of proving that they're not aggregating. But then not sure if we'd see them--oh wait, we could put QDs in with them.
Brian P. Josey 23:14, 9 April 2010 (EDT) This was actually the best photo that I took. The countertop and a lot of the other surfaces were reflective, so with the flash I kept getting washed out photos. Without the flash you could hardly see it. I didn't really realize it at first, but since today I have been getting more excited about the results. I really like Larry's idea, we should try it as soon as we get a chance. I can't wait to start doing more experiments.
Steve Koch 23:16, 9 April 2010 (EDT): Awesome! Yeah that was a good idea. I realized tonight that you can co-load with quantum dots and then would be able to see movement in the microscope (provided you could get the geometry sufficient). It still wouldn't be rock solid, unless you could prove that you're starting with single, non-aggregated proteins. In some sense, real experiments with fusion proteins sound almost easier :)
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